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Rates and activation parameters for the spontaneous cis to trans isomerization of the monoalkyl complexes (I) giving (II) are measured.
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ABSTRACT
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Polycrystalline powders of Na2xMn1−xPS3 have been synthesized from layered MnPS3 material by successive ion-exchange intercalation of potassium and sodium ions. Their x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger... more
Polycrystalline powders of Na2xMn1−xPS3 have been synthesized from layered MnPS3 material by successive ion-exchange intercalation of potassium and sodium ions. Their x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger spectroscopy spectra have been measured at room temperature using Mg Kα (1253.6 eV) x-ray source. In particular, the Mn, P, and S 2p and Na 1s and 2p core-level regions and the Na Auger KL23L23 transition have been investigated. All the analyzed XPS core-level spectra display a single-peak structure, suggesting the absence of nonequivalent atoms of Na, Mn, P, and S. The manganese XPS spectrum shows, as observed in MnPS3 and in its cesium and potassium intercalation compounds, typical shake-up satellites, suggesting that the Mn–S bond is yet mainly ionic in nature. The comparison with the XPS spectra relative to MnPS3 and its potassium intercalation compound (K2xMn1−xPS3) does not emphasize any relevant difference in the binding energy positions of the investigated core levels, indicating that sodium ion intercalation process does not alter the electronic properties of pure host matrix. Moreover, Na 2p core levels are discrete and well localized in agreement with the hypothesis of a weak link between the guest (the Na+ ions) and the host lattice (the negatively charged Mn1−xPS3 sheets). Such a hypothesis finds confirmation by the calculation of the Na modified Auger parameter.
Research Interests: Engineering, Chemistry, Applied Physics, X Rays, Mathematical Sciences, and 12 morePhysical sciences, Intercalation Chemistry, Potassium, Electronic properties, Spectrum, Room Temperature, Binding Energy, Porous Material, Ion Exchange, Electron Impact Ionization, X Ray Photoelectron Spectroscopy, and ionic bonding
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MALDI and ESI-MS have been applied to the characterization of the reaction products between the labile cis-[Pt(DMSO) 2 Cl 2 ] (1) and trans-[Pt(DMSO) 2 Cl(CH 3 )] (2) complexes with the simplest poly(amidoamine) ligand (PAMAM, G = 0,... more
MALDI and ESI-MS have been applied to the characterization of the reaction products between the labile cis-[Pt(DMSO) 2 Cl 2 ] (1) and trans-[Pt(DMSO) 2 Cl(CH 3 )] (2) complexes with the simplest poly(amidoamine) ligand (PAMAM, G = 0, 1,2-diaminoethane as core). The ...
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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Abstract Nanotherapeutics based on cyclodextrins (CD) have been designed to fight the antibiotic resistance and guarantee a successful outcome. Some of them are already on the market or are approaching the clinical phases. In this... more
Abstract Nanotherapeutics based on cyclodextrins (CD) have been designed to fight the antibiotic resistance and guarantee a successful outcome. Some of them are already on the market or are approaching the clinical phases. In this contribution, photo-independent/dependent strategies based on the use of CD nanocarriers delivering antibiotics/antibacterials, antivirals, antifungals, disinfectants, and antiseptics will be reviewed. Moreover nanophototherapeutics based on CD as antibacterials in photo-antimicrobial chemotherapy will be discussed. We will refer to the following nanosystems: (1) CD inclusion nanocomplexes; (2) nanoassemblies entirely composed by CD (i.e., vesicles, micelles, and nanospheres); (3) nanoparticles based on CD-polymer conjugates or CD inclusion complexes entrapped in polymeric matrixes; (4) nanoplatforms based on CD-carbon materials (i.e., carbon nanotubes or graphene derivatives); (5) silver decorated-CD nanostructures. CD-immobilized or cross-linked to fibers, textiles, or surface will not be reviewed in depth. These nanoantimicrobial systems will be reviewed with their in vitro and/or in vivo applications.
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Research Interests: Chemistry and Counterion
... Furthermore, porphyrins can coordinate a large variety of metal ions in the central macrocycle, leading to the possibility of accessing the rich chemical properties of these derivatives (eg spectroscopic and redox properties, electron... more
... Furthermore, porphyrins can coordinate a large variety of metal ions in the central macrocycle, leading to the possibility of accessing the rich chemical properties of these derivatives (eg spectroscopic and redox properties, electron density, axial coordination). ...
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Lithium intercalate thin films have been obtained from MnPS3 starting material and characterized by the x-ray photoelectron spectroscopy technique. The regions of Mn 2p and 3p, P and S 2p, and Li 1s core levels have been investigated. The... more
Lithium intercalate thin films have been obtained from MnPS3 starting material and characterized by the x-ray photoelectron spectroscopy technique. The regions of Mn 2p and 3p, P and S 2p, and Li 1s core levels have been investigated. The analysis of the spectra has revealed the lack of nonequivalent atoms of Mn, P and S, and Li. The presence of shake-up-type satellites at the Mn 2p and 3p core levels suggests that Li2xMn1−xPS3 is a large-gap insulating Mn compound analogously to the parent MnPS3. After lithium intercalation no remarkable shift has been observed in the binding energy positions of the investigated core levels in comparison with the corresponding MnPS3 pure compound. On these bases, we assume that only an ion transfer accompanies the lithium intercalation process.
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Sodium intercalated manganese thiophosphate Na0.62Mn0.69PS3 powders have been synthesized by a two-step ion-exchange process. Dielectric measurements have been performed as a function of both temperature and frequency on the prepared... more
Sodium intercalated manganese thiophosphate Na0.62Mn0.69PS3 powders have been synthesized by a two-step ion-exchange process. Dielectric measurements have been performed as a function of both temperature and frequency on the prepared samples in the 20–106 Hz frequency range over the 78–350 K temperature range by using the autobalancing bridge method. The temperature dependence of the dielectric constant imaginary part reveals the presence of a loss peak at the low temperatures together with a strong dispersion at the low frequencies and at the highest investigated temperatures. While the loss peak presence is characteristic for dipolar polarization processes, the strong low frequency dispersion at not very high temperatures, observed also in the dielectric constant real part, is typical for system with hopping charge carriers. A hypothesis about the nature of such carriers has been formulated on the basis of both the ion-exchange intercalation process and the comparison with the die...
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ABSTRACT
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We study the emission properties of a high quality monolithic microcavity with an embedded ultrathin organic tetrakis(4-methoxyphenyl)porphyrin layer. Spectral and angle-resolved photoluminescence measurements show a well defined... more
We study the emission properties of a high quality monolithic microcavity with an embedded ultrathin organic tetrakis(4-methoxyphenyl)porphyrin layer. Spectral and angle-resolved photoluminescence measurements show a well defined polarized doublet at detection angles larger than 15°. The splitting energy ranges up to 70 meV. The usual employed mechanism, based on the mismatch between the center of the mirror stop band and the wavelength of the microcavity, accounts only for a small fraction of the observed splitting. A transfer matrix model taking into account the optical anisotropy of the organic layer, has been employed to reproduce the observed experimental results. The anisotropy of the organic layer, confirmed by optical absorption spectroscopy, origins from a local molecular order as inferred by atomic force microscopy measurements.
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Aggregation of small molecules on a polymeric matrix, driven by electrostatic interactions, provides a simple and attractive strategy for building well-defined supramolecular species. By choosing matrices of different nature and length... more
Aggregation of small molecules on a polymeric matrix, driven by electrostatic interactions, provides a simple and attractive strategy for building well-defined supramolecular species. By choosing matrices of different nature and length together with the proper experimental conditions (pH, ionic strength, etc.) it is possible to tune the extent of aggregation and/or the size of the aggregates and, thereby, the “macroscopic” properties (absorption and emission features, redox potentials, etc.) of the supramolecular complex. It turns out that porphyrins are particularly good “bricks” for building these complexes, given their well known and tunable electronic properties (i.e., through the insertion of different metal ions and/or substituents on the porphyrin ring), . Recently, it has been reported that the water-soluble anionic porphyrin, mesotetrakis 4-sulphonatophenyl)-porphyrin (H2TPPS) (Figure 1), interacts with the protonated form of polylysine leading to the formation of aggregates [1].
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Nowadays, novel less-expensive nanoformulations for in situ-controlled and safe delivery of photosensitisers (PSs) against opportunistic pathogens in body-infections areas need to be developed. Antimicrobial photodynamic therapy (aPDT) is... more
Nowadays, novel less-expensive nanoformulations for in situ-controlled and safe delivery of photosensitisers (PSs) against opportunistic pathogens in body-infections areas need to be developed. Antimicrobial photodynamic therapy (aPDT) is a promising approach to treat bacterial infections that are recalcitrant to antibiotics. In this paper, we propose the design and characterization of a novel nanophototherapeutic based on the trade cyclodextrin CAPTISOL® (sulfobutylether-beta-cyclodextrin, SBE-βCD) and 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphine tetrakis(p-toluenesulfonate) (TMPyP) to fabricate efficient biocompatible systems for aPDT. Spherical nanoassemblies of about 360 nm based on CAPTISOL®/TMPyP supramolecular complexes with 1:1 stoichiometry and equilibrium binding constant (Kb ≅ 1.32 × 105 M-1) were prepared with entrapment efficiency of ≅ 100% by simple mixing in aqueous media and freeze-drying. These systems have been characterized by complementary spectroscopy and microscopy techniques. Time resolved fluorescence pointed out the strong interaction of porphyrin monomer within nanoassemblies (τ2 ≅ 11 ns with an amount of ca 90%) and scarce self-aggregation of porphyrins have been observed. Singlet oxygen comparative determination (ϕΔ CAPTISOL®/TMPyP = 0.58) assessed their photodynamic potential. Release and photostability studies have been carried out under physiological conditions pointing out the role of CAPTISOL® to sustain porphyrin release for more than 2 weeks and to protect PS from photodegradation. Finally, photoantimicrobial activity of nanoassemblies vs free porphyrin have been investigated against Gram-negative P. aeruginosa, E. coli and Gram-positive S. aureus. The proposed nanosystems were able to photokill both Gram-positive and -negative bacterial cells similarly to TMPyP at MBC90 = 6 µM of TMPyP and at 42 J/cm2 light dose. However, with respect to the less selective free TMPyP in biological sites, nanoassemblies exhibit sustained release properties and a higher photostability thus optimizing the PDT effect at the site of action. These results can open routes for in vivo translational studies on nano(photo)drugs and nanotheranostics based on less expensive formulations of CD and PS.
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When mixtures of D2 O/DCl are used to foster the self-assembly formation of TPPS4 porphyrin J-aggregates in aqueous solutions, an inverse kinetic isotope effect of 0.4 and an inverse equilibrium isotope effect of 0.6 are clearly detected.... more
When mixtures of D2 O/DCl are used to foster the self-assembly formation of TPPS4 porphyrin J-aggregates in aqueous solutions, an inverse kinetic isotope effect of 0.4 and an inverse equilibrium isotope effect of 0.6 are clearly detected. Most importantly, the addition of at least 10 % D2 O causes an inversion in the handedness of the final chiral J-aggregates, thus evidencing an important role of deuterium in driving the enantiomeric excess in the scalemic mixture of such supramolecular assemblies.
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The engineering of multifunctional nanoparticles carrying photosensitizer drugs (PS) and exposing binding groups for cellular receptors is of increasing interest in therapeutics and diagnostics applications. Natural and modified... more
The engineering of multifunctional nanoparticles carrying photosensitizer drugs (PS) and exposing binding groups for cellular receptors is of increasing interest in therapeutics and diagnostics applications. Natural and modified cyclodextrins (CDs) offer useful scaffolds to bind PS guests by supramolecular interactions. In particular, amphiphilic β-CDs, which form nanoaggregates of diverse shape and size according to the polarity of substituent groups on the rims, include in their different compartments as CD cavity, hydrophilic and hydrophobic portion, PS with different physicochemical properties. PS embedded in cationic amphiphilic CD nanoassemblies are effective in inducing photodynamic damage in cancer cells. For a carrier/PS system to be used in photodynamic therapy (PDT) or photodynamic diagnosis (PDD), the appropriate combination of the delivery characteristics with the preservation of the photodynamic activity of the PS is strictly required. Homogeneous multilayer films based on cationic amphiphilic β-CD entrapping anionic porphyrins can be constructed to exploit interfacial electrostatic interactions between the two components. The capability of CDs to generate restricted microenvironments for PS which can facilitate photoinduced energy transfer with suitable donor molecules was investigated for potential application in fluorescence diagnosis. Besides, recent findings suggest that PDT could represent a useful tool for properly addressing an alternative approach for killing pathogens and combating infections at a clinical level. Finally, modified CDs can bind gold nanoparticles, yielding hybrid organic/inorganic nanoparticles which were studied in water solution and after casting on solid substrates. These binary assemblies could further encapsulate PS or other conventional drugs, opening new intriguing routes on multimodal therapy.
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ABSTRACT A series of salts of the type [Pt(terpy)Me]X (X = Cl, NO3, PF6, ClO4, B(C6H5)(4)) containing a new organometallic complex cation of platinum(II) with 2,2':6',2 ''-terpyridine (terpy) were... more
ABSTRACT A series of salts of the type [Pt(terpy)Me]X (X = Cl, NO3, PF6, ClO4, B(C6H5)(4)) containing a new organometallic complex cation of platinum(II) with 2,2':6',2 ''-terpyridine (terpy) were synthesized and characterized by H-1, C-13, and Pt-195 NMR spectroscopy. No evidence for fluxionality of the terpyridine ligand was obtained, indicating that it is terdentate. The fourth position in the coordination plane is occupied by a methyl group. The resulting cation is unreactive toward substitution and is stable in aqueous solutions under mild conditions. The planarity and electron delocalization of the terpy moiety lead to extensive stacking interactions, forming dimers in dilute aqueous solution and larger aggregates when the concentration and/or the ionic strength increase. UV/vis and H-1 NMR spectra show characteristic dependencies on the concentration of the complex, the temperature, the solvent, and the ionic strength. Analysis of the absorption spectral data gives a value of 10 (+/-8) x 10(3) M(-1) (T = 298 K; mu = 0.101 mol L(-1)) for the dimerization equilibrium constant. Resonance light-scattering spectra, measured for the first time on a metal-containing noncyclic substrate, provide evidence for the tendency of the complex to form large self-aggregates even under low ionic strength conditions. The interaction of the cationic complex ion with calf thymus DNA was investigated by UV/vis, CD spectroscopy, resonance light-scattering, thermal denaturation, and gel electrophoresis mobility assays. At high r(f) ratios the complex seems to form extended aggregates on the surface of the nucleic acid, but at lower r(f) ratios evidence was obtained for intercalation.
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Under acidic conditions and at high ionic strength or in the presence of templating species, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS[Formula: see text] self-organizes into J-aggregates. In these species, the porphyrins align... more
Under acidic conditions and at high ionic strength or in the presence of templating species, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS[Formula: see text] self-organizes into J-aggregates. In these species, the porphyrins align in a general edge-to-edge geometry, responsible for their peculiar optical properties. The self-assembling process is hierarchical, and the kinetics are strongly dependent on the mixing protocols. In the case of sigmoidal profiles, the kinetic data have been treated using a model proposed in the literature by R.F. Pasternack. Accordingly, an autocatalytic growth with the formation of an [Formula: see text]-mer of porphyrin units is the rate-determining step (RDS) leading to the eventual J-aggregates whose size spans from nano- up to the micro-scale. The impact of different experimental parameters, together with inorganic counter-anions, and various cationic and anionic species (organic anions, metal ions, porphyrins, and metal complexes) will be reviewed.
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Research Interests: Pharmacology, Biochemistry, Chemistry, Medicine, Multidisciplinary, and 9 morePhotodynamic Therapy, Ps, SC, Singlet Oxygen, Acd, Langmuir, Oh, BODIPY, and O
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Abstract We report a hybrid nanoassembly based on gold colloids decorated with a new thiolated amphiphilic cyclodextrin complexing dopamine (AuNPs@SC16SH/DA). The novel amphiphilic β-cyclodextrin SC16SH, bearing on average one thiol group... more
Abstract We report a hybrid nanoassembly based on gold colloids decorated with a new thiolated amphiphilic cyclodextrin complexing dopamine (AuNPs@SC16SH/DA). The novel amphiphilic β-cyclodextrin SC16SH, bearing on average one thiol group at the end of an oligoethylene glycol chain per CyD unit, was obtained in a multi-step synthesis and fully characterized by NMR spectroscopy and MALDI analysis. The AuNPs@SC16SH hybrid assembly was prepared by mixing AuNPs and SC16SH in aqueous solution and investigated by UV/Vis and TEM measurements. The AuNPs@SC16SH/DA supramolecular assembly, bearing both thiol-stabilized gold nanoparticles and the neurotransmitter dopamine, has been conceived as stimuli-responsive delivery system able to control the release of dopamine upon proper stimuli. Two redox functionalities (i.e. the Au-S bond and the redox behaviour of dopamine) have been exploited to detach SC16SH/DA complex from the AuNPs@SC16SH/DA progenitor platform, using dithiothreitol (DTT), and to detect the complex by cyclic voltammetry (CV). Following, dopamine was finally released from the SC16SH/DA assembly upon treatment with Brij® S20 and the free dopamine was monitored by CV. Overall, our hybrid nanoassemblies turned out to be able to release dopamine, upon combined action of redox and digestion agents in medium emulating biological environment.
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The development of cyclodextrin nanoassemblies as useful carriers for photosensitizer drugs (PS) delivery in biological environment is a topic of increasing interest. In this paper, we present a spectroscopic investigation on a nanosystem... more
The development of cyclodextrin nanoassemblies as useful carriers for photosensitizer drugs (PS) delivery in biological environment is a topic of increasing interest. In this paper, we present a spectroscopic investigation on a nanosystem based on an amphiphilic cationic β-cyclodextrin derivative (CD-N) and an anionic porphyrin (TPPS). Nanoassemblies were prepared by hydration of an organic film containing the two species. The system was characterized by complementary techniques such as UV-vis, stationary and time-resolved fluorescence, and Dynamic Light Scattering (DLS) at different TPPS/CD-N molar ratios. Time-resolved fluorescence data showed that, at all the investigated molar ratios, TPPS is present both as self-aggregated species and monomers forming supramolecular adducts with CD-N. Moreover, DLS measurements evidenced families of aggregates having hydrodynamic radii ranging between 50 and 350 nm and the size distribution profile depending on the TPPS/CD-N molar ratio. At the...
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A series of polyamidoamine dendrimers (generations 1.5–4.0, with ethylenediamine as the central core) has been investigated in methanol solution by means of the small-angle X-ray scattering technique. The comparative analysis of the... more
A series of polyamidoamine dendrimers (generations 1.5–4.0, with ethylenediamine as the central core) has been investigated in methanol solution by means of the small-angle X-ray scattering technique. The comparative analysis of the structural properties of integer and half-integer generations of the dendrimers seems to be dominated by rather different trends. While the integer generations, bearing terminal amino groups, approach a
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ABSTRACT Li2xMn1-xPS3 films have been synthesized by exfoliating MnPS3 through the successive intercalations of K+ and Li+ ions. Their dielectric response has been measured from 80 to 350 K in the frequency range of (102–106) Hz. The... more
ABSTRACT Li2xMn1-xPS3 films have been synthesized by exfoliating MnPS3 through the successive intercalations of K+ and Li+ ions. Their dielectric response has been measured from 80 to 350 K in the frequency range of (102–106) Hz. The obtained data have been analyzed in terms of both complex permittivity ε* and the ac conductivity σ ac . The frequency dependence of σ ac has been interpreted in terms of the Jonscher’s law, whose exponent n decreases by increasing temperature. The n values lie between 0.479 and 0.501 and are typical of materials in which the ac conductivity is due to multiple hops of carriers. By analyzing the σ dc temperature dependence, the observed dielectric response has been attributed to the intercalated lithium ions, and the Li2xMn1-xPS3 films have been classified as hopping charge carrier systems.
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Publisher Summary This chapter outlines the structural characterization of colloidal cyclodextrins. Noncovalent interactions, such as hydrogen and iconic bonding, and hydrophobic and Van der Walls interactions are supposed to be the... more
Publisher Summary This chapter outlines the structural characterization of colloidal cyclodextrins. Noncovalent interactions, such as hydrogen and iconic bonding, and hydrophobic and Van der Walls interactions are supposed to be the driving forces in the formation of CD supramolecular aggregates. The chapter focuses on the self-organization of amphiphilic CD, which forms colloidal systems with specific functionalities. The potential aggregation of CD nanoaggregates and their nanostructural complexes with different guests in drug delivery will be mentioned. Light scattering and fluorescent techniques are presented in order to characterize in detail their structure in aqueous solution. The heterotopic colloids of amphiphilic cyclodextrins and photosensitizers are shown as potential novel systems for targeted photodynamic therapy of tumours (PDT).
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Properly functionalized amphiphilic cyclodextrins (CDs) can act as capping agents for gold colloids in solution (Mazzaglia, A.; et al. J. Phys. Chem. C 2008, 112, 6764). In the present work, we report a study on a hybrid gold... more
Properly functionalized amphiphilic cyclodextrins (CDs) can act as capping agents for gold colloids in solution (Mazzaglia, A.; et al. J. Phys. Chem. C 2008, 112, 6764). In the present work, we report a study on a hybrid gold nanoparticles/amphiphilic CD supramolecular system ...
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Cesium ions have been intercalated by ion exchange into layered manganese thiophosphate to produce Cs2xMn1−xPS3. Investigations have been conducted by x-ray diffraction analysis, IR absorption spectroscopy, x-ray photoemission... more
Cesium ions have been intercalated by ion exchange into layered manganese thiophosphate to produce Cs2xMn1−xPS3. Investigations have been conducted by x-ray diffraction analysis, IR absorption spectroscopy, x-ray photoemission spectroscopy (XPS), and dielectric spectroscopy. The XPS spectra, recorded at room temperature and at the Mn, P, and S 2p, Mn 3p, and Cs 3d and 4d core-level regions, indicate that no charge transfer occurs from guest species (Cs+) to pure host lattice (MnPS3). The presence of shake-up satellites at the Mn 2p and 3p core levels suggests that the cesium intercalation does not alter the nature of the Mn–S bond which is mostly ionic. Dielectric measurements, carried out between 260 and 375K and in the 20Hz–1MHz frequency range, classify Cs2xMn1−xPS3 as hopping charge carrier systems. The nature of such carriers can be hypothesized on the basis of both the intercalation process by cationic substitution and the comparison with the observed dielectric response of th...
Research Interests: Engineering, Chemistry, Applied Physics, Manganese, Mathematical Sciences, and 13 moreDielectric Spectroscopy, Absorption spectroscopy, Physical sciences, Intercalation Chemistry, Photoemission Spectroscopy, Ion, Room Temperature, Ion Exchange, Charge transfer, X Ray Diffraction Analysis, X Ray Photoelectron Spectroscopy, Caesium, and ionic bonding
ABSTRACT Intercalation of 9-aminoacridine (9AA: C13H10N2) in thin films of exfoliated Li2x−yMn1−xPS3 has been performed by means of a solution approach starting from the hydrochloride salt of the organic species (9AAHCl: C13H10N2·HCl).... more
ABSTRACT Intercalation of 9-aminoacridine (9AA: C13H10N2) in thin films of exfoliated Li2x−yMn1−xPS3 has been performed by means of a solution approach starting from the hydrochloride salt of the organic species (9AAHCl: C13H10N2·HCl). The resulting nanocomposite Li2x−yMn1−xPS3(C13H11N2)y films have been investigated by X-ray photoemission spectroscopy (XPS), at room temperature, in the regions of the Mn, P, S and Cl 2p, Li, C and N 1s and Mn 3p core levels. The XPS analysis has been also carried out on the 9-aminoacridine hydrochloride films whose XPS spectra have been compared with those of the Li2x−yMn1−xPS3(C13H11N2)y films to obtain information about the nature of the interaction between the guest species (9AAH+) and the matrix (Li2x−yMn1−xPS3 −).
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Abstract Camphorsulfonic (CSA) and p-toluenesulfonic (p-TsOH) acids promote the self-assembling process of the diacid meso-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. A general decrease of the rate constants on... more
Abstract Camphorsulfonic (CSA) and p-toluenesulfonic (p-TsOH) acids promote the self-assembling process of the diacid meso-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. A general decrease of the rate constants on increasing the acid concentration has been observed for these organic acids. For camphorsulfonic acid the formation of chiral J-aggregates, whose handedness is related to that of the acid, has been revealed by circular dichroism spectra. Changes in the aggregation rates, kinetic profiles and g-factors but no chiral discrimination have been observed for the two different enantiomers, when using different mixing protocols. Moreover, at high acid concentration, aggregation is inhibited and the formation of a new porphyrin species has been detected for both acids. This species has been characterized by steady-state and time-resolved spectroscopic techniques and has been ascribed to an ion pair between the diacid porphyrin and the organic counter-anion. Its role in the aggregation of the initial diacid species has been discussed.
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ABSTRACT In analogy to metal nanocomposites, the investigated hybrid organic–inorganic aggregates induce an enhancement of the scattered light. To explain the observed broadening of the absorption band and the wavelength dependence of the... more
ABSTRACT In analogy to metal nanocomposites, the investigated hybrid organic–inorganic aggregates induce an enhancement of the scattered light. To explain the observed broadening of the absorption band and the wavelength dependence of the scattering, the systems can be considered as a nanoparticle composite. The scattering enhancement obeys the scaling law with the same optical spectral dimension d0 = 0.3 as that obtained through numerical simulations on cluster–cluster aggregates of purely metal nanoparticle composites.
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Abstract A room temperature ionic liquid (RT-IL) made by the negatively charged water soluble meso-tetrakis(4 sulfonatophenyl)porphyrin (TPPS4) and the positively charged trihexyl(tetradecyl)phosphonium (CYPHOS® IL 101) has been... more
Abstract A room temperature ionic liquid (RT-IL) made by the negatively charged water soluble meso-tetrakis(4 sulfonatophenyl)porphyrin (TPPS4) and the positively charged trihexyl(tetradecyl)phosphonium (CYPHOS® IL 101) has been synthesized and fully characterized by NMR, MALDI-TOF, differential scanning calorimetry and thermogravimetric analyses. Moreover, the growth of nanosized porphyrin J-aggregates has been induced in solution through the “in situ” photogeneration of HCl acid in chlorinated solvent as well as the addition in solution of a strong chiral acid. In this latter case supramolecular chiral induction has been observed on the resulting emissive nanosized aggregates. The data reported clearly evidence the central role of trihexyl(tetradecyl)phosphonium (THTDP) counter-cation in i) determining the monomeric nature of the adduct in chlorinate solution, and ii) in limiting the size of the aggregates on a nanometric scale.
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The interaction between gold nanorods (Au NRs), synthesized by a conventional seeded growth protocol, and the anionic tetrakis-(4-sulfonatophenyl)porphyrin (TPPS4) has been investigated through various spectroscopic techniques. At neutral... more
The interaction between gold nanorods (Au NRs), synthesized by a conventional seeded growth protocol, and the anionic tetrakis-(4-sulfonatophenyl)porphyrin (TPPS4) has been investigated through various spectroscopic techniques. At neutral pH, the formation of H-aggregates and the inclusion of porphyrin monomers in CTAB micelles covering the nanorods have been evidenced. Under mild acidic conditions (pH=3) a nano-hybrid assembly of porphyrin J-aggregates and Au NRs has been revealed. For the sake of comparison, Cu(II) and Zn(II) metal porphyrin derivatives as well as a cationic porphyrin have been studied in the same experimental conditions, showing that: i) CuTPPS4 forms porphyrin H-dimers onto the Au NRs; ii) ZnTPPS4 undergoes to demetallation, followed by acidification of the central core and eventually aggregation onto Au NRs; iii) cationic porphyrin does not interact with Au NRs.
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Simple irradiation by UV light of porphyrin TpyP and its zinc(II) and manganese(III) metal derivatives in chlorinated solvents leads to the deposition on silica of mesoscale aggregates. The process is due to the photochemical... more
Simple irradiation by UV light of porphyrin TpyP and its zinc(II) and manganese(III) metal derivatives in chlorinated solvents leads to the deposition on silica of mesoscale aggregates. The process is due to the photochemical decomposition of the solvent with generation of HCl, which causes the precipitation of a protonated form. The morphology of the resulting objects is driven by the nature of the inserted metal ion.
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In this contribution we explore the capability of biocompatible nanoparticles (NPs) of cationic amphiphilic cyclodextrins entangling the anionic hydrophilic 5,10,15,20-tetrakis(4-sulfonatophenyl )-21H,23H-porphyrin (TPPS) to facilitate... more
In this contribution we explore the capability of biocompatible nanoparticles (NPs) of cationic amphiphilic cyclodextrins entangling the anionic hydrophilic 5,10,15,20-tetrakis(4-sulfonatophenyl )-21H,23H-porphyrin (TPPS) to facilitate photoinduced energy and electron transfer with ...
Research Interests: Engineering, Chemistry, Fluorescence Spectroscopy, Materials Chemistry, Photochemistry, and 13 moreFluorescence, Nanoparticle, Materials, Nanoparticles, Circular Dichroism, Electron Transfer, Anthracene, CHEMICAL SCIENCES, Porphyrin, Energy Transfer, Electron Acceptor, Photoinduced Electron Transfer, and Acceptor
The structure-making or breaking abilities of different anions, according to the Hofmeister series, play an important role in controlling the kinetics of growth and the chirality in porphyrin J-aggregates.
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... Andrea Santagati,*a Maria Modica,a Luigi MonsuÁ Scolarob and Maria Santagatia aDipartimento di Scienze Farmaceutiche, UniversitaÁ di Catania, CittaÁ Universitaria, Viale A. Doria, 6, 95125 Catania, Italy bDipartimento di Chimica ...... more
... Andrea Santagati,*a Maria Modica,a Luigi MonsuÁ Scolarob and Maria Santagatia aDipartimento di Scienze Farmaceutiche, UniversitaÁ di Catania, CittaÁ Universitaria, Viale A. Doria, 6, 95125 Catania, Italy bDipartimento di Chimica ... 18 KT Potts and DR Choudhury, J. Org. ...
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Depending on the experimental conditions, various charged water soluble porphyrins can aggregate, leading to large supramolecular assemblies whose basic building blocks are constituted by J-type aggregates or heteroaggregated species made... more
Depending on the experimental conditions, various charged water soluble porphyrins can aggregate, leading to large supramolecular assemblies whose basic building blocks are constituted by J-type aggregates or heteroaggregated species made up by oppositely charged ...
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A new porphyrin bearing four R or S hydrogenated citronellal units directly bound to the meso positions of the porphyrin ring was synthesized and fully characterized through MALDI-TOF, NMR, UV/Vis absorption, and fluorescence emission... more
A new porphyrin bearing four R or S hydrogenated citronellal units directly bound to the meso positions of the porphyrin ring was synthesized and fully characterized through MALDI-TOF, NMR, UV/Vis absorption, and fluorescence emission spectroscopies. Both enantiomers exhibit a monomeric nature in a series of organic solvents. Acting on the polarity of the solvent, i.e., increasing the amount of water in mixture with acetone, aggregation occurs, as revealed by UV/Vis absorption, fluorescence emission, and resonance light scattering. The occurrence of both H- and J-type aggregates was suggested by fluorescence lifetime measurements. In contrast to the monomeric species, these aggregates exhibit CD spectra reflecting the chirality of the building blocks. AFM microscopy shows that micrometer ribbon-like structures form by the casting solution of these porphyrins in acetone/water onto a glass surface. Chirality 00:000-000, 2015. © 2015 Wiley Periodicals, Inc.
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Under moderate acidic conditions, the cationic (+3) complexes ions tris(1,10-phenanthroline)cobalt(III), [Co(phen)3]3+, and hexamminecobalt(III), [Co(NH3)6]3+, efficiently promote the self-assembling process of the diacid... more
Under moderate acidic conditions, the cationic (+3) complexes ions tris(1,10-phenanthroline)cobalt(III), [Co(phen)3]3+, and hexamminecobalt(III), [Co(NH3)6]3+, efficiently promote the self-assembling process of the diacid 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. The growth kinetics have been analyzed according to a well-established autocatalytic model, in which the rate determining step is the initial formation of a nucleus containing m porphyrin units (in the range 2–3), followed by a stage whose rate constant kc evolves as a power of time. The observed catalytic rate constants and the extent of J-aggregation increase on increasing the metal complex concentration, with the phen complex being the less active. The UV/Vis extinction spectra display quite broad envelops at the J-band, especially for the amino-complex, suggesting that electronic dipolar coupling between chromophores is operative in these species. The occurrence of spontaneous symmetry...
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Under mild acidic conditions, various metal derivatives of tetrakis(4-N-methylpyridinium)porphyrin (gold(III), AuT4; cobalt(III), CoT4; manganese(III), MnT4 and zinc(II), ZnT4) catalytically promote the supramolecular assembling process... more
Under mild acidic conditions, various metal derivatives of tetrakis(4-N-methylpyridinium)porphyrin (gold(III), AuT4; cobalt(III), CoT4; manganese(III), MnT4 and zinc(II), ZnT4) catalytically promote the supramolecular assembling process of the diacid 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. The aggregation kinetics have been treated according to a well-established model that involves the initial formation of a critical nucleus containing m porphyrin units, followed by autocatalytic growth, in which the rate evolves as a power of time. An analysis of the extinction time traces allows to obtain the rate constants for the auto-catalyzed pathway, kc, and the number of porphyrins involved in the initial seeding. The aggregation kinetics have been investigated at fixed H2TPPS4 concentration as a function of the added metal derivatives MT4. The derived rate constants, kc, obey a rate law that is first order in [MT4] and depend on the specific nature of t...
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Chiral J-aggregates of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS[Formula: see text] have been obtained in ethanol solution triggered by addition of both enantiomeric forms of tartaric acid. A detailed spectroscopic investigation has... more
Chiral J-aggregates of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS[Formula: see text] have been obtained in ethanol solution triggered by addition of both enantiomeric forms of tartaric acid. A detailed spectroscopic investigation has been performed on aggregates obtained by a well-defined mixture protocol of reactants. Our findings show as both aggregation process and induced supramolecular chirality essentially depend on the concentration of the reactants. Contrary to what occurs in aqueous solution, TPPS4 in ethanol solution shows: (i) at low porphyrin concentration, an aggregation behavior characterized by a L-tartaric acid threshold whereas the D-tartaric does not work even at high concentrations, so revealing an enantiomeric discrimination; (ii) at high porphyrin concentration, a large kinetic discrimination of D- vs. L-enantiomer.
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A new porphyrin bearing four R or S hydrogenated citronellal units directly bound to the meso positions of the porphyrin ring was synthesized and fully characterized through MALDI-TOF, NMR, UV/Vis absorption, and fluorescence emission... more
A new porphyrin bearing four R or S hydrogenated citronellal units directly bound to the meso positions of the porphyrin ring was synthesized and fully characterized through MALDI-TOF, NMR, UV/Vis absorption, and fluorescence emission spectroscopies. Both enantiomers exhibit a monomeric nature in a series of organic solvents. Acting on the polarity of the solvent, i.e., increasing the amount of water in mixture with acetone, aggregation occurs, as revealed by UV/Vis absorption, fluorescence emission, and resonance light scattering. The occurrence of both H- and J-type aggregates was suggested by fluorescence lifetime measurements. In contrast to the monomeric species, these aggregates exhibit CD spectra reflecting the chirality of the building blocks. AFM microscopy shows that micrometer ribbon-like structures form by the casting solution of these porphyrins in acetone/water onto a glass surface. Chirality 00:000-000, 2015. © 2015 Wiley Periodicals, Inc.
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Treatment of 2,3,7,8,12,13,17,18-octakis(ethylsulfanyl)-5,10,15,20-porphyrazine (H2OESPz) with CrCl2 in a 1,2,4-trichlorobenzene–n-BuOH mixture resulted in one ethylsulfanyl branch at the pyrrolic β positions of the macrocycle being... more
Treatment of 2,3,7,8,12,13,17,18-octakis(ethylsulfanyl)-5,10,15,20-porphyrazine (H2OESPz) with CrCl2 in a 1,2,4-trichlorobenzene–n-BuOH mixture resulted in one ethylsulfanyl branch at the pyrrolic β positions of the macrocycle being replaced by an hydrogen atom with >40% yield. The structure of the asymmetric pyrrolic subunit and of the nearest pyrrolic subunits have been determined by NMR spectroscopy. The reaction path leading to the asymmetric porphyrazine implies the formation of a two-electron reduced diprotonated porphyrazine, [H2OESPz(−4)(2H+)], that, as a consequence of charge and structural intramolecular rearrangements at high temperature, undergoes nucleophilic substitution of an ethyl sulfide group by H−. UV-Vis and near-IR results suggest that the asymmetric substitution modifies the (sulfanyl)porphyrazine π and nSulfur levels. On the contrary, ESR spectroscopy shows that the electronic properties of the coordinated Cu2+ ion are affected only marginally. The half-waves of the ligand first reductive processes sensibly shift towards cathodic potentials in the asymmetric metal porphyrazines, but not in the asymmetric free-base porphyrazine, probably due to conflicting electronic and structural effects induced by removal of an ethylsulfanyl tail.
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Solvent vapour annealing (SVA) is used to control the reorganization of ultrathin films of three different polycyclic aromatic hydrocarbons self-assembled on solid surfaces. To this end, two perylene-bis(dicarboximide) (PDI) derivatives... more
Solvent vapour annealing (SVA) is used to control the reorganization of ultrathin films of three different polycyclic aromatic hydrocarbons self-assembled on solid surfaces. To this end, two perylene-bis(dicarboximide) (PDI) derivatives exposing branched side alkyl chains with ...
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... Rev. A, 40 (1989) 4665. [6] T. Vicsek, Fractal Growth Phenomena, Word Scientific, London, 1989. [7] RF Pastemak and EJ Gibbs, ACS Symp. Ser., 402 (1989) 59. [8] RF Pasternack, A. Giannetto, P. Pagano and EJ Gibbs, J. Am. Chem. Soc.,... more
... Rev. A, 40 (1989) 4665. [6] T. Vicsek, Fractal Growth Phenomena, Word Scientific, London, 1989. [7] RF Pastemak and EJ Gibbs, ACS Symp. Ser., 402 (1989) 59. [8] RF Pasternack, A. Giannetto, P. Pagano and EJ Gibbs, J. Am. Chem. Soc., 113 (1991) 7799. ...
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ABSTRACT Solvent vapour annealing allows macroscopic healing of molecular assemblies at surfaces to form suprastructures featuring a higher degree of order, and significant improvement of the performance of organic electronic devices.
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Recently some of us have shown that the cationic amphiphilic CD 1 (Fig. 1) entangles the hydrophilic porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin (TPPS) mainly by coulombic interactions, producing photoactivatable... more
Recently some of us have shown that the cationic amphiphilic CD 1 (Fig. 1) entangles the hydrophilic porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin (TPPS) mainly by coulombic interactions, producing photoactivatable nanoparticles.7 Beside, Liu and coworkers have ...
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... Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (8). [8](d). L. Antolini, AC Fabretti, G. Franchini, L. Menabue, GC Pellacani, H. Desseyn, R. Dommisse and HC Hoffmans. J. Chem. Soc. Dalton Trans. (1987), p. L227.... more
... Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (8). [8](d). L. Antolini, AC Fabretti, G. Franchini, L. Menabue, GC Pellacani, H. Desseyn, R. Dommisse and HC Hoffmans. J. Chem. Soc. Dalton Trans. (1987), p. L227. [9]. H. tom Dieck and M. Form. Angew. ...
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The photodynamic activity of a carrier-sensitizer system consisting of heterotopic colloidal nanoparticles (diameter 100-1000 nm) of a cationic amphiphilic cyclodextrin, heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD... more
The photodynamic activity of a carrier-sensitizer system consisting of heterotopic colloidal nanoparticles (diameter 100-1000 nm) of a cationic amphiphilic cyclodextrin, heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD (SC6CDNH2) encapsulating the anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin (TPPS) is investigated by an interdisciplinary approach involving the combination of time-resolved absorption and emission techniques with in vitro studies on cultured tumor cells. In a range of TPPS:SC6CDNH2 molar ratios between 1:10 and 1:50 these nanoparticles preserve the photodynamic properties of the entrapped photoactive agent. In fact, the triplet state of TPPS is efficiently populated, very long-lived and, as a consequence, able to produce singlet oxygen (the essential species for the photodynamic action) with quantum yield comparable to the free TPPS. Photodynamic efficacy of the carrier/sensitizer system is proven by in vitro studies on tumor Hela cells treated with TPPS:SC6CDNH2 at different molar ratio, showing significant cells death upon illumination with visible light.
Research Interests: Materials Science, Biomaterials, Drug delivery, Porphyrins, Medicine, and 15 moreMultidisciplinary, Photodynamic Therapy, Humans, Cancer Therapy, Cell Death, Nanostructures, Drug Delivery Systems, Photochemotherapy, HeLa cells, Neoplasms, Porphyrin, Cyclodextrins, In Vitro Studies, Quantum Yield, and Photosensitizer
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In the development of new antibacterial therapeutic approaches to fight multidrug-resistant bacteria, antimicrobial photodynamic therapy (aPDT) represents a well-known alternative to treat local infections caused by different... more
In the development of new antibacterial therapeutic approaches to fight multidrug-resistant bacteria, antimicrobial photodynamic therapy (aPDT) represents a well-known alternative to treat local infections caused by different microorganisms. Here we present a polypropylene (PP) fabric finished with citrate-hydroxypropyl-βCD polymer (PP-CD) entrapping the tetra-anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (TPPS) as photosensitizer eluting scaffold (PP-CD/TPPS) for aPDT. The concept is based on host-guest complexation of porphyrin in the cavities of CDs immobilized on the PP fibers, followed by its sustained and controlled delivery in release medium and simultaneous photo-inactivation of microorganisms. Morphology of fabric was characterized by optical (OM) and scanning electron microscopies (SEM). Optical properties were investigated by UV-vis absorption, steady- and time-resolved fluorescence emission spectroscopy. X-ray Photoelectron Spectroscopy (XPS) and FT-IR ...
Research Interests: Engineering, Textiles, Scanning Electron Microscopy, PHOTOELECTRON SPECTROSCOPY, Porphyrins, and 11 moreBiological Sciences, Staphylococcus aureus, Pseudomonas aeruginosa, CHEMICAL SCIENCES, Photochemotherapy, Fourier transform infrared spectroscopy, Cyclodextrins, Carboxylic Acids, Pseudomonas Aeruginosa, Polypropylenes, and Biomacromolecules
Spectroscopic methods have been employed in order to understand the molecular basis of the decrease in enzymatic activity of the antiinflammatory enzyme copper-zinc superoxide dismutase (SOD) following the covalent binding of... more
Spectroscopic methods have been employed in order to understand the molecular basis of the decrease in enzymatic activity of the antiinflammatory enzyme copper-zinc superoxide dismutase (SOD) following the covalent binding of polyethyleneglycol (PEG) chains to the protein amino-groups. The PEG modification is a general method recently proposed to improve the therapeutic index of enzymes. 1H NMR spectra on the cobalt substituted PEG-modified SOD, Cu2Co2-PEG-SOD, have been recorded. The signals are quite broad with respect to the unmodified enzyme. This has been interpreted on the basis of the effect of molecular weight on the linewidth. The analysis has shown that the histidine hydrogens involved in metal binding at the enzyme active site are the same in both native and PEG-modified SOD. Similarly, circular dichroism and absorption spectra indicate that the overall conformation of the metal clusters is not perturbed upon modification. On the other hand, azide titration shows that the affinity constant of N-3 for SOD is largely reduced upon PEG modification (K = 154 M-1 and 75 M-1 for the native and modified SOD, respectively). These results indicate that the decrease in enzymatic activity upon surface modification with PEG is not caused by a perturbation of the active site geometry, but to a decrease in the channeling of the O2- ion towards the enzyme active site.
Research Interests: Inorganic Chemistry, Kinetics, Nuclear Magnetic Resonance, Magnetic Resonance Spectroscopy, Circular Dichroism, and 13 moreSurface modification, Superoxide Dismutase, Active site, Spectrum analysis, Enzyme activity, Molecular weight, Inorganic Biochemistry, Reaction Kinetics, Absorption Spectra, Protons, Polyethylene Glycols, Molecular Structure, and therapeutic index
Research Interests: Chemical Engineering, Bioinformatics, Analytical Chemistry, Inorganic Chemistry, Coordination Chemistry, and 10 moreSpectroscopy, Life Sciences, Molecular modeling, Biomedical Research, Circular Dichroism, IT Value, Infrared, Quantum Yield, Sodium Dodecyl Sulfate, and bioinorganic chemistry and applications
... Antonino Mazzaglia,* † Mariachiara Trapani, ‡ Valentina Villari,* § Norberto Micali, § Francesca Marino Merlo, Daniela Zaccaria, Maria Teresa Sciortino, Francesco Previti, ‖ Salvatore Patanè, ‖ and Luigi Monsù Scolaro* ‡. ...
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ABSTRACT An organic/inorganic nanohybrid, based on the tetranionic mesotetrakis-(4-sulfonatophenyl)porphyrin (TPPS) and on a positively charged polyhedral oligomeric silsesquioxanes (POSS), has been synthesized and fully characterized.... more
ABSTRACT An organic/inorganic nanohybrid, based on the tetranionic mesotetrakis-(4-sulfonatophenyl)porphyrin (TPPS) and on a positively charged polyhedral oligomeric silsesquioxanes (POSS), has been synthesized and fully characterized. Differential scanning calorimetry and thermogravimetric analyses have allowed classifying this compound as a room temperature ionic liquid (RT-IL). The POSS bulky cation is responsible for the observed amorphous waxy solid appearance and for the high solubility in halogenated solvents. The formation of emissive nanosized porphyrin J-aggregates has been detected both in solution and on quartz cuvette surface upon light irradiation on a dichlorometane porphyrin/POSS solution.
... [8] G. ARENA, L. MONSU SCOLARO, RF PASTERNACK and R. ROMEO: submitted for publication. [9] RF PASTERNACK, EZ GIBBS and JJ VILLAFRANCA: Biochemistry, 22, 2406 (1983). [10] RF PASTERNACK: Ann. NY Acad. Sci., 206, 614 (1986). [11] CE... more
... [8] G. ARENA, L. MONSU SCOLARO, RF PASTERNACK and R. ROMEO: submitted for publication. [9] RF PASTERNACK, EZ GIBBS and JJ VILLAFRANCA: Biochemistry, 22, 2406 (1983). [10] RF PASTERNACK: Ann. NY Acad. Sci., 206, 614 (1986). [11] CE JOHNSON jr. ...
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Recently, we showed that J-aggregates, formed by the zwitterionic diacid form of the porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H 2 TPPS 4 4-) under acidic conditions, can be described in terms of fractal geometry. We have... more
Recently, we showed that J-aggregates, formed by the zwitterionic diacid form of the porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H 2 TPPS 4 4-) under acidic conditions, can be described in terms of fractal geometry. We have extended the investigation of the ...
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Water/decane/AOT microemulsions have been used to obtain J-aggregates of the anionic water soluble porphyrin tetrakis(4-sulfonatophenyl)porphyrin (TPPS 4 ), having sizes that are controlled by the dimension of the water pool. The kinetics... more
Water/decane/AOT microemulsions have been used to obtain J-aggregates of the anionic water soluble porphyrin tetrakis(4-sulfonatophenyl)porphyrin (TPPS 4 ), having sizes that are controlled by the dimension of the water pool. The kinetics of aggregation have been investigated ...
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A structural change from fractal to nanorod J-aggregates of tetrakis(4-sulfonatophenyl)porphyrin has been obtained by acting on the intermolecular interaction potential. The size and shape of these self-assembled porphyrin clusters have... more
A structural change from fractal to nanorod J-aggregates of tetrakis(4-sulfonatophenyl)porphyrin has been obtained by acting on the intermolecular interaction potential. The size and shape of these self-assembled porphyrin clusters have been monitored under different experimental conditions, by means of polarized and depolarized dynamic light scattering and small and wide angle elastic light scattering. At sufficiently low porphyrin concentration and high ionic strength, the shielded repulsive potential seems to be responsible for the fractal structure of the aggregates. On the contrary, at low ionic strength (nonshielded potential) and high porphyrin concentration, these species self-assemble in a rodlike arrangement. The length of the so-formed rod-shaped aggregates decreases on increasing porphyrin concentration. Moreover, both fractals and rods display a structure-dependent optical activity induced by a chiral template.
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UV/vis absorption and time-resolved fluorescence measurements on alcoholic solutions of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS(4)) in neutral and acid form have been performed as a function of the alcohol polarity. These... more
UV/vis absorption and time-resolved fluorescence measurements on alcoholic solutions of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS(4)) in neutral and acid form have been performed as a function of the alcohol polarity. These solutions show a peculiar behavior that mimics porphyrin in confined water solutions. In alcohols, TPPS(4) exhibits a metastable phase showing the formation of new species in analogy with the confined water environment of AOT microemulsions. Various species have been detected at different pH values and on aging the solutions. Under neutral pH conditions, the porphyrin is present as free base monomer (S415) with a small amount of H-dimeric species (S400). On aging, the S415 leads to the formation of a new species (S423), which has been assigned as a J-type dimer of the neutral porphyrin. The species S400 and S423 are not present in bulk water solution but are typical of TPPS(4) in confined water. On decreasing pH, the S415 almost immediately converts into the diacid form (S438), which evolves toward red-shifted J-aggregates (S490) and blue-shifted H-aggregates (S420). On decreasing alcohol polarity, the kinetic evolution from fresh to aged solution and from the monomeric diacid species to H- and J-aggregates speeds up. Exploiting the amphiphilic character of short chain alcohols and widely varying their polarity, we were able to enhance in bulk conditions the peculiar behavior observed in close proximity to the microemulsion wall.
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AOT/water/decane microemulsions have been used to entrap the water-soluble 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4). Quasi-elastic light scattering technique has confirmed the confinement of the porphyrin and its various... more
AOT/water/decane microemulsions have been used to entrap the water-soluble 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4). Quasi-elastic light scattering technique has confirmed the confinement of the porphyrin and its various aggregates into the inner water pool. Various species have been detected as function of the size of the microemulsions, concentration of the porphyrin, pH, and aging of the solutions by using a combination of UV-vis absorption, steady fluorescence emission, fluorescence lifetime measurements, and time-resolved fluorescence anisotropy. Under neutral pH conditions, the porphyrin is present as the free base monomer (S414) in the inner water compartment, and it is free to rotate when the size of the droplet is large enough and the porphyrin concentration is low. On increasing the concentration and/or decreasing the microemulsion size, a H-dimer of the free base (S406) is prevalently formed. Aging both the S414 and S406 species leads to the formation of a new species (S424), which has been postulated as a H-type dimer of the diacid porphyrin. On decreasing the pH, the species S414 and S406 almost instantaneously convert into the diacid porphyrin, which is monomeric (S434). This latter is an intermediate in the eventual formation of J-aggregated TPPS4 (S490). A marked stability has been observed for the S424 species, which do not interconvert on changing the pH of the bulk aqueous phase.
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The early stage of fractal porphyrin diffusion-limited aggregation (DLA), induced by addition of a polyamine, is observed in aqueous solution by enhanced Raman scattering and fluorescence quenching. The enhancement of Raman scattering is... more
The early stage of fractal porphyrin diffusion-limited aggregation (DLA), induced by addition of a polyamine, is observed in aqueous solution by enhanced Raman scattering and fluorescence quenching. The enhancement of Raman scattering is due to nonlinear optical properties typical of fractal composites. Although this early stage (reaction-limited aggregation) has been theoretically predicted (by mean-field theory and molecular dynamics simulation), it is experimentally difficult to observe. During this initial stage, fluorescence quenching gives direct information on the decrease of the concentration of monomeric porphyrins, whereas Raman scattering (through characteristic vibrational modes of the aggregate) reports on the concentration of porphyrins in the aggregated form. These small clusters constitute the seeds for the DLA aggregation process leading to micrometric-sized fractals.
Research Interests: Engineering, Fluorescence Spectroscopy, Nonlinear Optics, Crystallization, Porphyrins, and 12 moreComputer Simulation, Mathematical Sciences, Physical sciences, Infrared, Molecular Conformation, Raman Scattering, Raman Spectra, Aqueous Solution, Mean Field Theory, Molecular Dynamic Simulation, Dimerization, and Fluorescence quenching
We performed an experimental investigation on the scattering and extinction properties of an aqueous solution of spermine-induced fractal J aggregates, constituted by porphyrin molecules. In analogy with nanostructured particle... more
We performed an experimental investigation on the scattering and extinction properties of an aqueous solution of spermine-induced fractal J aggregates, constituted by porphyrin molecules. In analogy with nanostructured particle composites, the dipolar moments of different porphyrins, not belonging to the aggregates J, are coupled and generate a strong light scattering enhancement. Both the enhanced scattered intensity and the imaginary part of the polarizability of the system obey scaling laws with the optical spectral dimension d0=0.3.
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The balance between hydrophobic and hydrophilic components in amphiphilic β-cyclodextrins, targeted by receptor specific groups (SC6CDGlc, SC6CDGal, SC16CDGlc, SC16CDGal), sensitively influences the structural properties of these systems.... more
The balance between hydrophobic and hydrophilic components in amphiphilic β-cyclodextrins, targeted by receptor specific groups (SC6CDGlc, SC6CDGal, SC16CDGlc, SC16CDGal), sensitively influences the structural properties of these systems. The ...
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The neutralization reaction between the meso-tetrakis(4-carboxyphenyl)porphyrin (TPPC) and O-(2-aminopropyl)-O'-(2-methoxyethyl)poly(propylene glycol) (Jeffamine M-600) in 1:4 stoichiometric ratio affords a stable supramolecular... more
The neutralization reaction between the meso-tetrakis(4-carboxyphenyl)porphyrin (TPPC) and O-(2-aminopropyl)-O'-(2-methoxyethyl)poly(propylene glycol) (Jeffamine M-600) in 1:4 stoichiometric ratio affords a stable supramolecular adduct (TPPC@Jeffamine). This species has been ...
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CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, V.le F. Stagno d'Alcontres 31, 98166 Messina, Italy. ... Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, and CIRCMSB,... more
CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati, V.le F. Stagno d'Alcontres 31, 98166 Messina, Italy. ... Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, and CIRCMSB, Universit di Messina, V.le F. Stagno d'Alcontres 31, 98166, ...
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Simple irradiation by UV light of porphyrin TpyP and its zinc(II) and manganese(III) metal derivatives in chlorinated solvents leads to the deposition on silica of mesoscale aggregates. The process is due to the photochemical... more
Simple irradiation by UV light of porphyrin TpyP and its zinc(II) and manganese(III) metal derivatives in chlorinated solvents leads to the deposition on silica of mesoscale aggregates. The process is due to the photochemical decomposition of the solvent with generation of HCl, which causes the precipitation of a protonated form. The morphology of the resulting objects is driven by the nature of the inserted metal ion.
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A new water soluble tetranuclear platinum(II) porphyrin complex cation has been synthesized through the coordination of four [ Pt (2,2′:6′,2″-terpyridine)] moieties to the pyridyl groups of 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphine... more
A new water soluble tetranuclear platinum(II) porphyrin complex cation has been synthesized through the coordination of four [ Pt (2,2′:6′,2″-terpyridine)] moieties to the pyridyl groups of 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphine (TPyP). The porphyrin derivative has been fully characterized by a combination of spectroscopic techniques. The high positive charge of the complex cation (8+) inhibits the aggregation in aqueous solution at low concentrations. By increasing the ionic strength, the electrostatic repulsion is screened leading to the formation of large unstable aggregates. The formation of microsized globular objects still emissive on the solid state is easily achieved by simple evaporation from diluted solutions. The solubilization of the complex in anionic aqueous surfactant solutions (sodium dodecyl sulfate, SDS) has revealed the inclusion of the complex ion in the hydrophobic region of the micelles as a monomeric species. Kinetics of Cu(II) insertion into the free...
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A non-covalent supramolecular approach to build up mesoscopic fractal J-aggregates of meso-tetrakis(4-sulfonatophenyl)porphyrin by using different polyamines under mild acidic conditions is reported. Spermine-induced J-aggregates have... more
A non-covalent supramolecular approach to build up mesoscopic fractal J-aggregates of meso-tetrakis(4-sulfonatophenyl)porphyrin by using different polyamines under mild acidic conditions is reported. Spermine-induced J-aggregates have been treated as a model system for a kinetic investigation. The kinetic analysis has been performed through two non-conventional approaches as function of a different reagent mixing protocol. In particular, an autocatalytic pathway in which the formation of aggregation nuclei is the rate-determining step is found when porphyrin is added to the reaction mixture as first reagent. In order to gain information on this early stage, a kinetic investigation has been carried out as function of different parameters, such as pH, and both spermine and porphyrin concentration. The nucleation becomes particularly evident when polyamines with fewer than three protonable nitrogen atoms are used. In these cases, a sort of "YES/NO" effect for the aggregation ...
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The ability to control the spatial arrangement of porphyrins through non covalent intermolecular interactions is very important for accessing advanced functional materials with peculiar optical properties.1,2 The extent of... more
The ability to control the spatial arrangement of porphyrins through non covalent intermolecular interactions is very important for accessing advanced functional materials with peculiar optical properties.1,2 The extent of self-aggregation can be controlled by a series of factors, ...
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ABSTRACT Small angle light and X-ray scattering and scaling concepts are used to explore the intra- and inter-molecular structure of two different classes of new materials: dendritic polymer and porphyrins systems. Whereas porphyrins in... more
ABSTRACT Small angle light and X-ray scattering and scaling concepts are used to explore the intra- and inter-molecular structure of two different classes of new materials: dendritic polymer and porphyrins systems. Whereas porphyrins in water are characterized, depending on their concentration and ionic strength, by the built-up of extended clusters, dendrimers or ''starburst polymers'' display an internal self-similar structure.
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Abstract N, N′-di-butyldithiooxamide, n bu 2-DTO, reacts in chloroform with neutral complexes of the type cis-PtL 2 Cl 2. When L= bz 2 S or Image COD the tight contact ion pair {Pt (H 2-n bu 2-DTO) 2 2+,(Cl−) 2}(1) is obtained for any... more
Abstract N, N′-di-butyldithiooxamide, n bu 2-DTO, reacts in chloroform with neutral complexes of the type cis-PtL 2 Cl 2. When L= bz 2 S or Image COD the tight contact ion pair {Pt (H 2-n bu 2-DTO) 2 2+,(Cl−) 2}(1) is obtained for any metal to ligand ratio. When L is ...
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... toward a cyclometallated platinum(II) complex: evaluation of steric and electronic contributions Raffaello Romeo a.., Maria Rosaria Plutino '1, Luigi Monstl Scolaro a ... therein; (b) G. Alibrandi, D. Minniti, L. Monsil Scolaro... more
... toward a cyclometallated platinum(II) complex: evaluation of steric and electronic contributions Raffaello Romeo a.., Maria Rosaria Plutino '1, Luigi Monstl Scolaro a ... therein; (b) G. Alibrandi, D. Minniti, L. Monsil Scolaro and R, Romeo, lnorg, Chem., 28 (1989) 1939; (el U. Frey. ...
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For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H(4)TPPS(4)) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS(4) formation. When copper salts are added last, the... more
For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H(4)TPPS(4)) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS(4) formation. When copper salts are added last, the kinetic profile is fit as a (pseudo)-first-order process. However, J-aggregates of the H(4)TPPS(4) porphyrin are rapidly formed at pH ~ 3 when Cu(II) salts are incorporated in solution prior to porphyrin addition. The subsequent porphyrin units metalation leads to the disassembling of these arrays via a pseudo-zero-order kinetic profile, suggesting an attack of the metal ion at the rims of the nanostructure.
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Two-electron reduction of alkyl(sulfanyl)porphyrazines: a route to free-base and peripherally metallated asymmetric porphyrazinesElectronic supplementary information (ESI) available: 13C NMR spectra of H2OOSPz, H2HOSPz, H2HOSPz(Br) and [H2OOSPz]PtCl2, MALDI-MS and IR spectra of [H2OOSPz]PtCl2. Se...more
Treatment of octakis(octylthio)porphyrazine (H(2)OOSPz) with cis-bis(benzonitrile)dichloroplatinum(II) in a 1,2,4-trichlorobenzene (TCB)-n-BuOH mixture at 190 degree C affords the asymmetric porphyrazine... more
Treatment of octakis(octylthio)porphyrazine (H(2)OOSPz) with cis-bis(benzonitrile)dichloroplatinum(II) in a 1,2,4-trichlorobenzene (TCB)-n-BuOH mixture at 190 degree C affords the asymmetric porphyrazine 2H-heptakis(octylthio)porphyrazine, H(2)HOSPz, in ca. 40% yield. In the key synthetic step the two-electron reduced diprotonated porphyrazine, [H(2)OOPz(4-)(H(+))(2)](hemiporphyrazinogen), forms in nearly quantitative yield. This species undergoes nucleophilic substitution of an octylsulfide group by H(-), affording the asymmetric porphyrazine, this process being favoured by the high-temperature induced charge and structural intramolecular rearrangements. The resulting molecule shows mesomorphic behaviour. Interestingly, in the presence of sodium acetate, or in neat TCB, the asymmetric porphyrazine does not form at all. Under these conditions, a PtCl(2) molecular fragment coordinates both to a porphyrazine aza bridge and to a thioether moiety leading to the formation of the [H(2)OOSPz]PtCl(2) complex. The S,N-coordination of the PtCl(2) unit was proved by (1)H, (195)Pt[(1)H], and (13)C NMR spectroscopy, and supported by DFT (B3LYP) calculations. The complex conjugates high asymmetry with strong solvatochromism and, therefore, it is potentially interesting for nonlinear optics.
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The binding of a tetracationic porphyrin to a highly charged polymer like poly(sodium vinylsulfonate) has been investigated over a wide pH range and under various experimental conditions. We present evidence that, depending on the pH, the... more
The binding of a tetracationic porphyrin to a highly charged polymer like poly(sodium vinylsulfonate) has been investigated over a wide pH range and under various experimental conditions. We present evidence that, depending on the pH, the high electrostatic field exerted by the polymer stabilizes the diprotonated form of the free base porphyrin at unusual pH values or otherwise causes the formation of H-type aggregates. In particular, at a low polymer concentration, lowering the pH at first allows the formation of the diacid species then it determines its reorganization in close-packed J-type aggregates. The employment of various metallo-derivatives of the title porphyrin enables a better insight into the nature of all the detected species.
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Well-defined arrays of porphyrins attached to a rigid polyisocyanide backbone have been synthesized and their physical and optical properties studied. The helical polymers are rigidified by an inter-side chain hydrogen-bonded network and... more
Well-defined arrays of porphyrins attached to a rigid polyisocyanide backbone have been synthesized and their physical and optical properties studied. The helical polymers are rigidified by an inter-side chain hydrogen-bonded network and have an average mass of 1.1 x 10(6) Daltons and a polydispersity index of 1.3. Each of the polymer strands contains four columns of around 200 stacked porphyrins and has an overall length of 87 nm. The chromophores are arranged in a left-handed helical fashion along the polymer backbone. Photophysical studies show that at least 25 porphyrins within one column are excitationally coupled.
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ANTONINO MAZZAGLIA1,2∗, LUIGI MONSU' SCOLARO1,2,3, RAPHAEL DARCY4, RUTH DONOHUE4 and BART JAN RAVOO4 1Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Unitá di Messina, Salita Sperone 31, 98166, Messina, Italy; 2INFM,... more
ANTONINO MAZZAGLIA1,2∗, LUIGI MONSU' SCOLARO1,2,3, RAPHAEL DARCY4, RUTH DONOHUE4 and BART JAN RAVOO4 1Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Unitá di Messina, Salita Sperone 31, 98166, Messina, Italy; 2INFM, Unit`a di Messina, Messina, ...
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Tetrakis(4-sulfonatophenyl) porphine (TPPS4) molecules form complexes with chrysotile nanotubes in a chloroform-methanol solvent; the self-assembly is driven by Coulombic attractions. The UV/vis absorption spectrum indicates... more
Tetrakis(4-sulfonatophenyl) porphine (TPPS4) molecules form complexes with chrysotile nanotubes in a chloroform-methanol solvent; the self-assembly is driven by Coulombic attractions. The UV/vis absorption spectrum indicates J-aggregation. In AFM, the complexes appear as ...
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For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H(4)TPPS(4)) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS(4) formation. When copper salts are added last, the... more
For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H(4)TPPS(4)) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS(4) formation. When copper salts are added last, the kinetic profile is fit as a (pseudo)-first-order process. However, J-aggregates of the H(4)TPPS(4) porphyrin are rapidly formed at pH ~ 3 when Cu(II) salts are incorporated in solution prior to porphyrin addition. The subsequent porphyrin units metalation leads to the disassembling of these arrays via a pseudo-zero-order kinetic profile, suggesting an attack of the metal ion at the rims of the nanostructure.
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For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H(4)TPPS(4)) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS(4) formation. When copper salts are added last, the... more
For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H(4)TPPS(4)) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS(4) formation. When copper salts are added last, the kinetic profile is fit as a (pseudo)-first-order process. However, J-aggregates of the H(4)TPPS(4) porphyrin are rapidly formed at pH ~ 3 when Cu(II) salts are incorporated in solution prior to porphyrin addition. The subsequent porphyrin units metalation leads to the disassembling of these arrays via a pseudo-zero-order kinetic profile, suggesting an attack of the metal ion at the rims of the nanostructure.
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Abstract The kinetics of the reaction cis-[PtR 2 (Me 2 SO) 2]+ bpy→[PtR 2 (bpy)]+ 2Me 2 SO (R= CH 3, C 6 H 6; BPY= 2.2′-bipyridine) have been studied in the coordinating solvent acetonitrile, where sulfoxide complexes are in equilibrium... more
Abstract The kinetics of the reaction cis-[PtR 2 (Me 2 SO) 2]+ bpy→[PtR 2 (bpy)]+ 2Me 2 SO (R= CH 3, C 6 H 6; BPY= 2.2′-bipyridine) have been studied in the coordinating solvent acetonitrile, where sulfoxide complexes are in equilibrium with the solvento species cis-[ ...
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ABSTRACT
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The reaction of 2,2'-dilithiumbiphenyl with cis-[PtCl(2)(SEt(2))(2)] at -10 degrees C in diethyl ether not only leads to the main product... more
The reaction of 2,2'-dilithiumbiphenyl with cis-[PtCl(2)(SEt(2))(2)] at -10 degrees C in diethyl ether not only leads to the main product [Pt(2)(micro-SEt(2))(2)(bph)(2)], containing the planar 2,2'-biphenyl dianion (bph(2)(-)), but also forms a new dinuclear platinum(II) compound of formula [Pt(2)(micro-SEt(2))(2)(Hbph)(4)], 1a (Hbph(-) = eta(1)-biphenyl monoanion), in which each metal is in a square-planar environment. NMR spectroscopy and molecular mechanics (MMFF) calculations were used to characterize 1a. The results suggest that the favored conformation for the four Hbph biphenyl groups is alphabetabetaalpha. In chloroform solution, 1a undergoes atropisomerization to 1b (alphabetaalphabeta) (k(is) = 1.03 x 10(-)(4) s(-)(1), at 298 K) that subsequently cyclometalates (k(obs) = 4.48 x 10(-)(6) s(-)(1), at 298 K) to yield [Pt(2)(micro-SEt(2))(2)(bph)(2)] and biphenyl. Both processes, atropisomerization and C-H activation, presumably involve preliminary thioether bridge splitting. The dinuclear complex 1a has been shown to be a versatile and useful precursor to a variety of mononuclear eta(1)-biphenyl platinum(II) complexes. By reaction with diethyl sulfide, dimethyl sulfoxide, or with rigid dinitrogen containing ligands, such as 2,2'-bipyridine or 1,10-phenanthroline, complexes cis-[Pt(Hbph)(2)(dmso)(2)] 3, cis-[Pt(Hbph)(2)(SEt(2))(2)] 4, [Pt(Hbph)(2)(bpy)] 5, and [Pt(Hbph)(2)(phen)] 6 were obtained, respectively. The crystal structures of compounds 5 and 6 were determined. Only the head-to-tail isomer of these compounds was recognized in the solid state and in solution, where restricted rotation around the Pt-C bond prevents interconversion to the head-to-head form. A detailed kinetic study of ligand (dmso) exchange and substitution (by 2,2'-bipyridine and 1,10-phenanthroline) has been performed on complex 3 in CDCl(3) and toluene-d(8) by (1)H NMR magnetization transfer experiments, and in toluene by UV/vis spectroscopy, respectively. The rates of both processes show no dependence on ligand concentration, the rate of ligand substitution being in reasonable agreement with that of ligand exchange at the same temperature. The kinetics are characterized by largely positive entropies of activation. The results are consistent with a dissociative mode of activation analogous to the pattern already found for compounds with a similar [Pt(C,C)(S,S)] set of coordinating ligands. The role of ML(3) d(8) T-shaped 14-electron species, as elusive reaction intermediates or structurally characterized compounds, is discussed.
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The copper(II) derivative of the dicationic trans-bis(N-methylpyridinium-4-yl)diphenylporphyrin (t-CuPagg) forms large fractal aggregates in aqueous solution under moderate ionic strength conditions. A kinetic investigation of the... more
The copper(II) derivative of the dicationic trans-bis(N-methylpyridinium-4-yl)diphenylporphyrin (t-CuPagg) forms large fractal aggregates in aqueous solution under moderate ionic strength conditions. A kinetic investigation of the aggregation process allows for a choice of experimental conditions to quickly obtain stable assemblies in solution. These positively charged aggregates are able to interact efficiently with negatively charged chiral species, (including bacterial spores) leading to induced circular dichroism signals in the Soret region of the porphyrin, now acting as a sensitive chiroptical probe.
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ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select... more
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The 9-(bromoalkyl)-1,4-dimethyl-9H-carbazoles (2a-d) derivatives, characterized by the presence of five or seven methylenic spacer groups bonded to the carbazolic nitrogen, have been synthesized from the corresponding... more
The 9-(bromoalkyl)-1,4-dimethyl-9H-carbazoles (2a-d) derivatives, characterized by the presence of five or seven methylenic spacer groups bonded to the carbazolic nitrogen, have been synthesized from the corresponding 1,4-dimethyl-9H-carbazole and appropriate dibromoalkyl by following a general synthetic method. All the prepared species have been fully characterized by means of IR, and 1H and 13C NMR spectroscopy, GC-MS and Elemental analysis. Good crystals of the 2c have been obtained and the crystal structure has been solved by means of X-ray diffractometry. In order to study the cytotoxic effect of 2a, 2b, 2c, 2d carbazole derivatives on A2780 ovarian cancer cells, we performed MTT assay after exposure of this cell population to those compounds in a concentration range from 1 to 10μM. Finally, we want to verify whether the cytotoxic effect of the 2c carbazole is mediated by apoptotic mechanisms, by performing chromatin condensation assay on the A2780 cell cultures upon the carbaz...
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ABSTRACT In this work the deposition of a tetrakis(4-sulfonatophenyl)porphyrin (TPPS) film onto optical fiber tip is obtained via a non-conventional procedure consisting in a UV-light induced deposition. This leads to the growth of TPPS... more
ABSTRACT In this work the deposition of a tetrakis(4-sulfonatophenyl)porphyrin (TPPS) film onto optical fiber tip is obtained via a non-conventional procedure consisting in a UV-light induced deposition. This leads to the growth of TPPS thin films right at the core region of the fiber end. The simplicity and cost effectiveness of this procedure, as well as the potential of porphyrins as functional materials, enable the design of novel active and passive in-fiber devices. Here, the presence of intense, narrow bands in the reflected spectra is successfully exploited to detect corrosive or toxic vapors, such as strong volatile acids and bases, at room temperature.
A series of monoalkyl square-planar complexes of the type [Pt(N-N)(CH(3))(Me(2)SO)]PF(6) (1-14), where N-N represents chelating diamines or diimines of widely different steric and electronic characteristics, was synthesized, and the... more
A series of monoalkyl square-planar complexes of the type [Pt(N-N)(CH(3))(Me(2)SO)]PF(6) (1-14), where N-N represents chelating diamines or diimines of widely different steric and electronic characteristics, was synthesized, and the complexes were fully characterized as solids and in solution. The substrates were tailored to offer only one site of exchange to a neutral molecule, i.e. Me(2)SO, in a noncoordinating solvent. No evidence for fluxionality of the N-N ligands was found, except for the case of complex 11 formed by 2,9-dimethyl-1,10-phenanthroline. In solution this complex is fluxional with the phenanthroline oscillating between nonequivalent bidentate modes by a mechanism which involves rupture of the metal-nitrogen bond and rapid interconversion of two coordinatively unsaturated T-shaped 14-electron three-coordinate molecular fragments. Rates of this fluxion were measured by NMR spectroscopy from the exchange effects on the (1)H signals of the methyl and aromatic hydrogens. The DeltaG() value for the fluxion is 49.6 +/- 4 kJ mol(-)(1). Dimethyl sulfoxide exchange with all the complexes has been studied as a function of ligand concentration by (1)H NMR line-broadening, isotopic labeling, and magnetization transfer experiments with deuterated acetone as the solvent. Second-order rate constants were obtained from linear plots of k(obs) vs [Me(2)SO] and activation parameters were obtained from exchange experiments carried out at different temperatures. Second-order kinetics and negative entropies of activation indicate an associative mechanism. The lability of dimethyl sulfoxide in the complexes depends in a rather unexpected and spectacular way upon the nature of the coordinate N-N ligands, the difference in reactivity between the first (N-N = N,N,N',N'-tetramethyl-1,2-diaminoethane, k(2)(298) = (1.15 +/- 0.1) x 10(-)(6) mol(-)(1) s(-)(1)) and the last (N-N = 2,9-dimethyl-1,10-phenanthroline, k(2)(298) = (3.81 +/- 0.005) x10(4) mol(-)(1) s(-)(1)) members of the series being greater than 10 orders of magnitude, as a result of a well-known phenomenon of steric retardation (for the first complex) and an unprecedented case of steric acceleration (for the last complex). Other factors of primary importance in controlling the reactivity are (i) the presence of an extensive pi system on the ligand N-N, (ii) the ease with which this pi system interacts with nonbonding d electrons of the metal, and (iii) the flexibility and ease of elongation of the chelate bite distance. The basicity plays a somewhat minor role, except in the restricted range of the same class of compounds such as substituted phenanthrolines.
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Polarization modulated scanning near-field optical microscopy (PM-SNOM) is effective in detecting circular and linear dichroism with sub-wavelength resolution. PM-SNOM investigation of the chiroptical properties of single ribbon-like... more
Polarization modulated scanning near-field optical microscopy (PM-SNOM) is effective in detecting circular and linear dichroism with sub-wavelength resolution. PM-SNOM investigation of the chiroptical properties of single ribbon-like nanosized J-aggregates formed by acid induced aggregation of tris-(4-sulfonatophenyl)phenylporphyrin is reported. Linear dichroism maps give evidence of well-organized chromophores packed in linear arrays within the structure of the nanoribbons. Circular dichroism maps indicate that the molecules forming the nanoribbon have an inherently chiral structure at the local scale.
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The assembly among gold nanoparticles, the water-soluble tetrakis(4-sulfonatophenyl)porphyrin and spermine, in acidic solution, forms a hybrid nanocomposite exhibiting scattering enhancement. A scaling law of a cluster−cluster aggregate... more
The assembly among gold nanoparticles, the water-soluble tetrakis(4-sulfonatophenyl)porphyrin and spermine, in acidic solution, forms a hybrid nanocomposite exhibiting scattering enhancement. A scaling law of a cluster−cluster aggregate of metal nanoparticle ...
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Depending on the experimental conditions, various charged water soluble porphyrins can aggregate, leading to large supramolecular assemblies whose basic building blocks are constituted by J-type aggregates or heteroaggregated species made... more
Depending on the experimental conditions, various charged water soluble porphyrins can aggregate, leading to large supramolecular assemblies whose basic building blocks are constituted by J-type aggregates or heteroaggregated species made up by oppositely charged ...
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UV-visible absorption measurements have been applied to the study of the aggregation kinetics of the porphyrin t-H 2 P agg in aqueous solution. The temporal evolution of the spectra can be related to the time dependence of the monomer... more
UV-visible absorption measurements have been applied to the study of the aggregation kinetics of the porphyrin t-H 2 P agg in aqueous solution. The temporal evolution of the spectra can be related to the time dependence of the monomer concentration and the mean cluster size. ...
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We used small angle x-ray scattering to study interparticle structural properties of polyamidoamine starburst dendrimers (PAMAM, with an ethylenediamine central core) in methanol solutions. We have explored the intensity profiles for... more
We used small angle x-ray scattering to study interparticle structural properties of polyamidoamine starburst dendrimers (PAMAM, with an ethylenediamine central core) in methanol solutions. We have explored the intensity profiles for solutions of starbursts of different generations ...
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The tetrabutylammonium salt of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) is soluble in dichloromethane, and the general properties of this compound have been investigated as function of various added acids HX (X = Cl, Br, I,... more
The tetrabutylammonium salt of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) is soluble in dichloromethane, and the general properties of this compound have been investigated as function of various added acids HX (X = Cl, Br, I, CF(3)COO, CF(3)SO(3), TFPB) through UV-vis absorption spectroscopy, steady state fluorescence emission, and resonance light-scattering (RLS) techniques. Upon addition of HX, the initial monomeric free base TPPS is readily converted in an aggregated species, whose spectroscopic features are independent of the nature of the counteranion X. All the spectroscopic evidence suggest a J-type arrangement of chromophores in this aggregate, involving strong hydrogen bonds, electrostatic, and dispersive interactions. In the specific case of chloride and bromide, in the presence of a TBAX excess, the addition of the corresponding acid leads to a monomeric ion-pair between the TBA cations and the diacid TPPS, whose central core is strongly interacting with the halide. On further increasing the acid concentration in these latter solutions, fully protonated species are formed that eventually start to aggregate.
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The amyloidogenic amino acid sequence Ac-VHSSNNFGAILSS-NH(2), corresponding to the 17-29 peptide region of human amylin (hIAPP17-29), was modified by grafting a hydrophilic PEG chain in order to obtain a novel class of peptides to be used... more
The amyloidogenic amino acid sequence Ac-VHSSNNFGAILSS-NH(2), corresponding to the 17-29 peptide region of human amylin (hIAPP17-29), was modified by grafting a hydrophilic PEG chain in order to obtain a novel class of peptides to be used as models to study the aggregation process of the full-length IAPP. The amphiphilic feature of the pegylated peptide fragment at the N-terminus (PEG-N-hIAPP17-29) drives the aggregation process toward stable micellar clusters without fibrillogenesis, despite the presence of beta-sheet interaction between peptides at pH values higher than 4.0. The hIAPP17-29-C-PEG, in which the PEG moiety is linked to the C-terminus, does not possess analogous amphiphilic character and the ability of PEG in forming H-bonds with the solvent overcomes that of the peptide chain, thereby causing peptide flocculation. The comparison with the unmodified hIAPP17-29 and the rat's peptide sequence Ac-VRSSNNLGPGLPP-NH(2)(rIAPP17-29) revealed the crucial role of hydrogen bonding between peptide and solvent in determining the aggregate structure and preventing fibril formation, as well as the non-negligible effect of a small amount of organic solvent in the aqueous solution which affects the aggregation process and rate.
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Samples containing J-aggregates formed by the porphyrin meso-tetrakis(4-sulfonatophenyl)porphine (H 2 TPPS 4 4-) were studied by a combination of elastic (ELS) and dynamic (DLS) light scattering techniques. Aggregation was fostered by... more
Samples containing J-aggregates formed by the porphyrin meso-tetrakis(4-sulfonatophenyl)porphine (H 2 TPPS 4 4-) were studied by a combination of elastic (ELS) and dynamic (DLS) light scattering techniques. Aggregation was fostered by lowering the pH and increasing the ionic ...
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ABSTRACT
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ABSTRACT The integration of a tetrakis(4-sulfonatophenyl)porphyrin (TPPS) thin film with optical fiber technology is obtained via a non-conventional procedure consisting in a UV-light induced deposition. This leads to the growth of TPPS... more
ABSTRACT The integration of a tetrakis(4-sulfonatophenyl)porphyrin (TPPS) thin film with optical fiber technology is obtained via a non-conventional procedure consisting in a UV-light induced deposition. This leads to the growth of TPPS thin films right at the core region of the fiber end. The simplicity and cost effectiveness of this procedure, as well as the potential of porphyrins as functional materials, enable the design of novel active and passive in-fiber devices. Here, the presence of intense, narrow bands in the reflected spectra is successfully exploited to detect corrosive or toxic vapors, such as strong volatile acids and bases, at room temperature.
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Light scattering and time-resolved fluorescence spectroscopy results showed that specially designed amphiphilic cyclodextrins are able to bind a specific protein, PA-I lectin. When containing a galactosyl group, the self-assembled... more
Light scattering and time-resolved fluorescence spectroscopy results showed that specially designed amphiphilic cyclodextrins are able to bind a specific protein, PA-I lectin. When containing a galactosyl group, the self-assembled cyclodextrins interact with the protein affecting the dynamical properties of the system and the fluorescence lifetimes (as well as the fluorescence anisotropy) of the protein itself. The self-assembled cyclodextrins containing a
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Positively charged, synthetic chrysotile nanotubes act as inorganic tectons supporting H- and J-type aggregates of anionic porphyrins with markedly different optical properties, making these nanohybrid materials of interest for... more
Positively charged, synthetic chrysotile nanotubes act as inorganic tectons supporting H- and J-type aggregates of anionic porphyrins with markedly different optical properties, making these nanohybrid materials of interest for application in nanotechnology.
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The reaction of 2,2'-dilithiumbiphenyl with cis-[PtCl(2)(SEt(2))(2)] at -10 degrees C in diethyl ether not only leads to the main product... more
The reaction of 2,2'-dilithiumbiphenyl with cis-[PtCl(2)(SEt(2))(2)] at -10 degrees C in diethyl ether not only leads to the main product [Pt(2)(micro-SEt(2))(2)(bph)(2)], containing the planar 2,2'-biphenyl dianion (bph(2)(-)), but also forms a new dinuclear platinum(II) compound of formula [Pt(2)(micro-SEt(2))(2)(Hbph)(4)], 1a (Hbph(-) = eta(1)-biphenyl monoanion), in which each metal is in a square-planar environment. NMR spectroscopy and molecular mechanics (MMFF) calculations were used to characterize 1a. The results suggest that the favored conformation for the four Hbph biphenyl groups is alphabetabetaalpha. In chloroform solution, 1a undergoes atropisomerization to 1b (alphabetaalphabeta) (k(is) = 1.03 x 10(-)(4) s(-)(1), at 298 K) that subsequently cyclometalates (k(obs) = 4.48 x 10(-)(6) s(-)(1), at 298 K) to yield [Pt(2)(micro-SEt(2))(2)(bph)(2)] and biphenyl. Both processes, atropisomerization and C-H activation, presumably involve preliminary thioether bridge splitting. The dinuclear complex 1a has been shown to be a versatile and useful precursor to a variety of mononuclear eta(1)-biphenyl platinum(II) complexes. By reaction with diethyl sulfide, dimethyl sulfoxide, or with rigid dinitrogen containing ligands, such as 2,2'-bipyridine or 1,10-phenanthroline, complexes cis-[Pt(Hbph)(2)(dmso)(2)] 3, cis-[Pt(Hbph)(2)(SEt(2))(2)] 4, [Pt(Hbph)(2)(bpy)] 5, and [Pt(Hbph)(2)(phen)] 6 were obtained, respectively. The crystal structures of compounds 5 and 6 were determined. Only the head-to-tail isomer of these compounds was recognized in the solid state and in solution, where restricted rotation around the Pt-C bond prevents interconversion to the head-to-head form. A detailed kinetic study of ligand (dmso) exchange and substitution (by 2,2'-bipyridine and 1,10-phenanthroline) has been performed on complex 3 in CDCl(3) and toluene-d(8) by (1)H NMR magnetization transfer experiments, and in toluene by UV/vis spectroscopy, respectively. The rates of both processes show no dependence on ligand concentration, the rate of ligand substitution being in reasonable agreement with that of ligand exchange at the same temperature. The kinetics are characterized by largely positive entropies of activation. The results are consistent with a dissociative mode of activation analogous to the pattern already found for compounds with a similar [Pt(C,C)(S,S)] set of coordinating ligands. The role of ML(3) d(8) T-shaped 14-electron species, as elusive reaction intermediates or structurally characterized compounds, is discussed.
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Interactions between cationic or anionic porphyrins and templates with opposite charges have been extensively investigated for their possible biomedical 1 and technological applications. 2 The formation of binary heteroassemblies of... more
Interactions between cationic or anionic porphyrins and templates with opposite charges have been extensively investigated for their possible biomedical 1 and technological applications. 2 The formation of binary heteroassemblies of oppositely charged porphyrins has also ...
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In this contribution we explore the capability of biocompatible nanoparticles (NPs) of cationic amphiphilic cyclodextrins entangling the anionic hydrophilic 5,10,15,20-tetrakis(4-sulfonatophenyl )-21H,23H-porphyrin (TPPS) to facilitate... more
In this contribution we explore the capability of biocompatible nanoparticles (NPs) of cationic amphiphilic cyclodextrins entangling the anionic hydrophilic 5,10,15,20-tetrakis(4-sulfonatophenyl )-21H,23H-porphyrin (TPPS) to facilitate photoinduced energy and electron transfer with ...
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Research Interests: Biophysics, Inorganic Chemistry, Enzyme Inhibitors, Fluorescent Dyes and Reagents, Polarography, and 15 moreDNA, High Pressure Liquid Chromatography, Cisplatin, DNA binding, Atomic Absorption Spectrophotometry, Conformational Analysis, Gel electrophoresis, Biological activity, Antitumor Activity, Cell free System, Organometallic Compounds, Antineoplastic Agents, Heterocyclic compounds, Nucleic Acid Conformation, and Biochemistry and cell biology
Organometallic cationic complex ions of the type [Pt(R-terpy)R′]Cl (R = H, Ph; R′ = Me, Ph) are soluble and stable in aqueous solution, where they self-aggregate to form large supramolecular assemblies. The interaction of these aggregates... more
Organometallic cationic complex ions of the type [Pt(R-terpy)R′]Cl (R = H, Ph; R′ = Me, Ph) are soluble and stable in aqueous solution, where they self-aggregate to form large supramolecular assemblies. The interaction of these aggregates with calf thymus DNA was investigated ...
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The ligand exchange rate constants for the reactions [Pt(bph)(SR2)2] + 2*SR2 --> [Pt(bph)(*SR2)2] + 2SR2 (bph = 2,2'-biphenyl dianion; R = Me and Et) and cis-[PtPh2(SMe2)2] + 2*SMe2 --> cis-[PtPh2(*SMe2)2] + 2SMe2... more
The ligand exchange rate constants for the reactions [Pt(bph)(SR2)2] + 2*SR2 --> [Pt(bph)(*SR2)2] + 2SR2 (bph = 2,2'-biphenyl dianion; R = Me and Et) and cis-[PtPh2(SMe2)2] + 2*SMe2 --> cis-[PtPh2(*SMe2)2] + 2SMe2 have been determined in CDCl3 as a function of ligand concentration and temperature, by 1H NMR isotopic labeling and magnetization transfer experiments. The rates of exchange show no dependence on ligand concentration and the kinetics are characterized by largely positive entropies of activation. The kinetics of displacement of the thioethers from [Pt(bph)(SR2)2] with the dinitrogen ligands 2,2'-bipyridine and 1,10-phenanthroline (N-N) to yield [Pt(bph)(N-N)], carried out in the presence of sufficient excess of thioether and N-N to ensure pseudo-first-order conditions, follow a nonlinear rate law k(obsd) = a[N-N]/(b[SR2] + [N-N]). The general pattern of behavior indicates that the rate-determining step for substitution is the dissociation of a thioether ligand and the formation of a three-coordinated [Pt(bph)(SR2)] intermediate. The value of the parameter a, which measures the rate of ligand dissociation, is constant and independent of the nature of N-N, and it is in reasonable agreement with the value of the rate of ligand exchange at the same temperature. Theoretical ab initio calculations were performed for both [Pt(bph)(SMe2)2] and cis-[PtPh2(SMe2)2], and for their three-coordinated derivatives upon the loss of one SMe2 ligand. The latter optimize in a T-shaped structure. Calculations were performed in the HF approximation (LANL2DZ basis set) and refined by introducing the correlation terms (Becke3LYP model). The activation enthalpies from the optimized vacuum-phase geometries are 52.3 and 72.2 kJ moll compared to the experimental values in CDCl3 solution, 80 +/- 1 and 93 +/- 1 kJ mol(-1) for [Pt(bph)(SMe2)2] and cis-[PtPh2(SMe2)2], respectively. The electrostatic potential maps of both parent compounds show a remarkable concentration of negative charge over the platinum atom which exerts a repulsion force on an axially incoming nucleophile. On the other hand, the strength of the organic carbanions trans to the leaving group and the stabilization of the T-shaped intermediate in the singlet ground state may also rationalize the preference for the dissociative mechanism. All of the kinetic and theoretical data support the latter hypothesis and indicate, in particular, that dissociation from the complex containing the planar 2,2'-biphenyl dianion is easier than from its analogue with single aryl ligands. Electron back-donation from filled d orbitals of the metal to empty pi* of the in-plane cyclometalated rings is weak or absent and is not operative in promoting an associative mode of activation.
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... Raffaello Romeo;vt Antonio Grassi,'*+ and Luigi Monsii Scolarot Dipartimento di Chimica Inorganica e Struttura Molecolare, Universita di Messina, Salita Sperone 3 1, Vill. ... (4) (a) Lanza, S.; Minniti, D.; Moore, P.;... more
... Raffaello Romeo;vt Antonio Grassi,'*+ and Luigi Monsii Scolarot Dipartimento di Chimica Inorganica e Struttura Molecolare, Universita di Messina, Salita Sperone 3 1, Vill. ... (4) (a) Lanza, S.; Minniti, D.; Moore, P.; Sachinidis, J.; Romeo, R.; Tobe, ML Inorg. Chem. ...
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Aggregation of water-soluble porphyrins on polymeric matrixes is, in principle, a simple strategy for building tailored supramolecular species. To date, only interactions of porphyrins with matrices carrying opposite charges have been... more
Aggregation of water-soluble porphyrins on polymeric matrixes is, in principle, a simple strategy for building tailored supramolecular species. To date, only interactions of porphyrins with matrices carrying opposite charges have been studied because of the repulsion between ...
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(PEt3) 2HX] hydride products. The distribution of the olefin products, 1-butene, cis-2-butene, and trans-2-butene is also dependent on the nature of X. The most probable mechanism for the thermolysis involves fast and reversible 0-hydride... more
(PEt3) 2HX] hydride products. The distribution of the olefin products, 1-butene, cis-2-butene, and trans-2-butene is also dependent on the nature of X. The most probable mechanism for the thermolysis involves fast and reversible 0-hydride elimination and olefin insertion in a ...
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... (1) Chatt, J.; Shaw, B. L. J. Chem. SOC. 1959, 705, 4020. (2) Costanzo, L. 1.; Giuffrida, S.; Romeo, R. Inorg. Chim. Acra 1980,38, 31. (3) Cross, R. Chem. SOC. Reu. 1980, 9, 185.Romeo, R.; Uguagliati, P.; Belluco, U. J. Mol. Catal.... more
... (1) Chatt, J.; Shaw, B. L. J. Chem. SOC. 1959, 705, 4020. (2) Costanzo, L. 1.; Giuffrida, S.; Romeo, R. Inorg. Chim. Acra 1980,38, 31. (3) Cross, R. Chem. SOC. Reu. 1980, 9, 185.Romeo, R.; Uguagliati, P.; Belluco, U. J. Mol. Catal. 1975, I , 325. ...
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The rates of chloride for triphenylphosphine substitution have been measured in dichloromethane for a series of cyclometalated [Pt(N-N-C)Cl] complexes containing a number of terdentate N-N-C anionic ligands, derived from deprotonated... more
The rates of chloride for triphenylphosphine substitution have been measured in dichloromethane for a series of cyclometalated [Pt(N-N-C)Cl] complexes containing a number of terdentate N-N-C anionic ligands, derived from deprotonated alkyl-, phenyl-, and benzyl-6-substituted 2,2'-bipyridines. These rates have been compared with those of the corresponding [Pt(N-N)(C)Cl] (N-N = 2,2'-bipyridine; C = CH3 or C6H5) complexes having the same set of donor atoms but less constrained arrangements of the ligands. The reactions of the cyclometalated compounds occur as a single-stage conversion from the substrate to the ionic pair [Pt(N-N-C)(PPh3)]Cl products. There is no evidence by 1H and 31P(1H) NMR spectroscopy for the formation of other Pt(II) species or of concurrent ring-opening processes. In contrast, in the monoalkyl- or monoaryl-2,2'-bipyridine complexes, chloride substitution is followed by subsequent slower processes which involve the detachment of one arm of the chelated 2,2'-bipyridine, fast cis to trans isomerization of the cis-[Pt(PPh3)2(eta 1-bipy)(R)]+ transient intermediate, and, eventually, the release of free bipy, yielding trans-[Pt(PPh3)2(R)Cl] (R = Me or Ph). All reactions are first-order with respect to complex and phosphine concentration, obeying the simple rate law kobsd = k2[PPh3]. The values of the second-order rate constant k2 do not seem particularly sensitive to the nature of the bonded organic moiety (alkyl or aryl), to its structure (cyclometalated or not), to the size of the ring, or to the number of alkyl substituents on it. The effects are those foreseen on the basis of an associative mode of activation. The only exception to this pattern of behavior is constituted by the complex [Pt(bipy phi-H)Cl] (bipy phi = 6-phenyl-2,2'-bipyridine), which features a significant rate enhancement with respect to the analogue [Pt(bipy)(Ph)Cl] complex. The results of this work, together with those of a previous paper, suggest that there is not a specific role of cyclometalation in controlling the reactivity, unless an in-plane aryl ring becomes part of the pi-acceptor system of the chelated 2,2-bipyridine, behaving as a cyclometalated analogue of the nitrogen terdentate 2,2':6',2"-terpyridine.
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In 1970, when few people believed that Rosenberg'sobservation of the carcinostatic properties of cis-[Pt (NH3) 2Clz] would have any medical consequences,] we started an extensive study, as part of a consortium funded by... more
In 1970, when few people believed that Rosenberg'sobservation of the carcinostatic properties of cis-[Pt (NH3) 2Clz] would have any medical consequences,] we started an extensive study, as part of a consortium funded by Rustenberg Platinum Mines, of the ...
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The molecular structure of the title compound, the first reported for a trans-(dimethyl sulfoxide) platinum (II) complex, shows a significant lengthening of the Pt-S bond. Observed consequences are an easy hydrolysis and trans to cis... more
The molecular structure of the title compound, the first reported for a trans-(dimethyl sulfoxide) platinum (II) complex, shows a significant lengthening of the Pt-S bond. Observed consequences are an easy hydrolysis and trans to cis isomerism, which takes place in ...
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... References. F Russo, S Guccione and G Romeo et al., Eur J Med Chem 27 (1992), pp. 7380. ... F Russo, G Romeo, S Guccione and A De Blasi, J Med Chem 34 (1991), pp. 18501854. Full Text via CrossRef | View Record in Scopus | Cited By... more
... References. F Russo, S Guccione and G Romeo et al., Eur J Med Chem 27 (1992), pp. 7380. ... F Russo, G Romeo, S Guccione and A De Blasi, J Med Chem 34 (1991), pp. 18501854. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (36). ...
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ABSTRACT New tripodal ligands 2,4,6-triethyl-1,3,5-tris{[1-(2-pyridinyl)ethenyl]sulfinylmethyl}benzenes 6, characterized by three pendant chains each containing both sulfoxide and pyridine moieties, were synthesized from the corresponding... more
ABSTRACT New tripodal ligands 2,4,6-triethyl-1,3,5-tris{[1-(2-pyridinyl)ethenyl]sulfinylmethyl}benzenes 6, characterized by three pendant chains each containing both sulfoxide and pyridine moieties, were synthesized from the corresponding sulfenic acid and 2-ethynylpyridine. Two diastereomeric mixtures were obtained and separated, one racemic mixture 6a, having a C3 symmetry axis and the other 6b with no symmetry. With the aim of studying the coordination ability of these chelating-κN,κS type ligands, monobranched racemic [1-(2-pyridinyl)ethenyl]sulfinylbenzene 9 was also synthesized. Upon addition of an equivalent amount of the monochelating ligand 9 or the tripodal species 6a to a CD3CN solution of a platinum(II) complex of the type cis-[PtMe2(Me2SO)2] (Pt1) or trans-[PtMeCl(Me2SO)2] (Pt2), platinum(II) coordination and chelation occurred, as definitively indicated by a sharp change in the 1H NMR spectrum towards the final corresponding chelated platinum(II) species and free dimethyl sulfoxide. The prepared platinum(II) species contain one or three fragments of the type {PtMe2}(10 or 12) and {PtMeCl}(11 or 13) bound to the pyridinyl/sulfinyl skeleton in the coordinating ligands 9 and 6a. All the prepared species were fully characterized by NMR spectroscopy from the connectivities in 2D-COSY, 1H-13C HSQC and phase-sensitive 2D-NOESY spectra which confirm the molecular mechanics calculation predictions.
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Reactions of the cationic complex ions [PtMe(Me2SO)(PP)]+ (PP = dppf... more
Reactions of the cationic complex ions [PtMe(Me2SO)(PP)]+ (PP = dppf (1,1'-bis(diphenylphosphino)ferrocene) and dppe (1,2-bis(diphenylphosphino)ethane)) with 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphyrin (TpyP) led to the formation of the symmetrical tetraplatinated porphyrin complexes, [PtMe(PP)]4TpyP.X4 (PP = dppf, X = CF3SO3-, 3, and PP = dppe, X = BF4-, 5) containing the organometallic fragment [PtMe(PP)]. The precursor sulfoxide platinum complexes [PtMe(Me2SO)(dppf)]CF3SO3, 2 and [PtMe(Me2SO)(dppe)]BF4, 4, were prepared by halide abstraction from [PtMeCl(dppf)], 1, and by controlled protonolysis of [PtMe2(dppe)] respectively, in the presence of a small amount of dimethyl sulfoxide. All these starting platinum(II) compounds, as well as the porphyrin derivatives 3 and 5, were fully characterized through elemental analysis, 1H NMR mono- and bidimensional, 31P[1H], 31P-1H HMBC, UV/Vis absorption and photophysical measurements. The X-ray crystal structure of complex 1 has been determined. In order to ascertain the electronic influence of ferrocene, the spectroscopic and redox properties of 3 were compared with those of TPyP and of the analogous 5. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), 1H and 31P NMR data, and UV/Vis data, all suggest a certain degree of communication between the central porphyrin and the peripheral hetero-bimetallic fragments. In contrast, no detectable interaction among these peripheral groups seem to come into play. Unlikely from the porphyrin derivative 5, formation of well defined fluorescent mesoscopic ring structures was easily achieved by simple evaporation from diluted dichloromethane solutions of 3.
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Dye systems are generally based on aromatic compounds possessing wide planar regions and a consequent large electron delocalization. The main property, a variety of absorption features in the visible spectra of light, is the basis of... more
Dye systems are generally based on aromatic compounds possessing wide planar regions and a consequent large electron delocalization. The main property, a variety of absorption features in the visible spectra of light, is the basis of their use in fundamental research and in ...
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ABSTRACT In analogy to metal nanocomposites, the investigated hybrid organic–inorganic aggregates induce an enhancement of the scattered light. To explain the observed broadening of the absorption band and the wavelength dependence of the... more
ABSTRACT In analogy to metal nanocomposites, the investigated hybrid organic–inorganic aggregates induce an enhancement of the scattered light. To explain the observed broadening of the absorption band and the wavelength dependence of the scattering, the systems can be considered as a nanoparticle composite. The scattering enhancement obeys the scaling law with the same optical spectral dimension d0 = 0.3 as that obtained through numerical simulations on cluster–cluster aggregates of purely metal nanoparticle composites.
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The deposition of the porphyrin has been achieved by pulsed irradiation of a diluted solution of the tetrabutylammonium salt of TPPS in CH 2 Cl 2 ( 3−4 μM) by using a deuterium lamp (see Supporting Information). The Soret band at 420 nm... more
The deposition of the porphyrin has been achieved by pulsed irradiation of a diluted solution of the tetrabutylammonium salt of TPPS in CH 2 Cl 2 ( 3−4 μM) by using a deuterium lamp (see Supporting Information). The Soret band at 420 nm gradually decreases in intensity, ...
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Systematic work on the synthesis and characterization of two series (referred to as type A and B) of poly(amido-amine)s with tertiary amino-groups in the main chain is reported. The polymers were synthesized by polyaddition of alpha,... more
Systematic work on the synthesis and characterization of two series (referred to as type A and B) of poly(amido-amine)s with tertiary amino-groups in the main chain is reported. The polymers were synthesized by polyaddition of alpha, omega-bis-(methyl-amino) alkanes with 1,4-bis-acryloylpiperazine (type A) and 1,12-bis-acryloyl-n-diaminododecane (type B). These materials, which will be employed in the preparation of block and graft copolymers for biomedical use, have been characterized by means of various techniques and the most interesting features are reported.
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ANTONINO MAZZAGLIA1,2∗, LUIGI MONSU' SCOLARO1,2,3, RAPHAEL DARCY4, RUTH DONOHUE4 and BART JAN RAVOO4 1Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Unitá di Messina, Salita Sperone 31, 98166, Messina, Italy; 2INFM,... more
ANTONINO MAZZAGLIA1,2∗, LUIGI MONSU' SCOLARO1,2,3, RAPHAEL DARCY4, RUTH DONOHUE4 and BART JAN RAVOO4 1Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Unitá di Messina, Salita Sperone 31, 98166, Messina, Italy; 2INFM, Unit`a di Messina, Messina, ...