The rapid development in polymer chemistry has, in recent years, led to the introduction of polym... more The rapid development in polymer chemistry has, in recent years, led to the introduction of polymeric materials in the field of medicine. Two major groups of polymers are used for medical applications: prosthetic and biologically active materials. We synthesized copolymers with the main chain consisting of poly (methyl methacrylate) and graft chains of poly(ethylene glycol) (COP GRAFT). Changes were made in the graft copolymer chains for a possible incorporation of a drug, such that it may be used for the controlled release of drugs. The synthesis of these new compounds is based on two synthetic routes and FTIR, differential scanning calorimetry (DSC), thermogravimetry (TGA) and X-ray diffraction (XRD) characterized the products formed at the end of each stage. Through FTIR we observed absorption bands characteristic of P-H, P=O and P-O bonds that were inserted into the polymer chain during phosphorylation of the COP GRAFT, beyond the absorption bands characteristic of the copolymer before phosphorylation, such as C=O and CO. By TGA and DSC we observed that only the diisobutyl copolymer has endothermic transition temperature and degradation behavior consistent with a polymer. XRD results showed a structural and conformational change in crystallinity of modified chains. Molecular weight and polydispersity of COPGRAFT obtained by GPC increased after phosphorylation with diisobutyl group. The phosphorylation reaction was efficient in obtaining diisobutyl copolymer and the applied techniques confirmed the modification of the COPGRAFT chains.
Three new metal-free copolymeric fluorophores, which present unusual and strong fluorescence NIR ... more Three new metal-free copolymeric fluorophores, which present unusual and strong fluorescence NIR emission were synthesized through low-cost, easy, fast and efficient direct electropolymerization methodology without use of expensive catalysts or chemical coupling reactions. The tailoring of these novel more conjugated and polarized molecules was based on the Donor-Acceptor (D-A) approach. The three new designed binary molecular hybrids were obtained by direct oxidative electrocopolymerization with the well-known electron-donating (D) EDOT (3,4-ethylenedioxythiophene) and the electron-acceptor unit (A) ThCO-NHAr. This bis-functionalized molecular block was synthesized between the β-carboxythiophene (ThCO) with electron-donating and fluorescent aromatic amines (naphthylamine (NFT), aminofluorene (FLU) and aminodibenzofuran (DBF)). These monomers were submitted to copolymerization and three novel copolymers-PEDOT-co-2NFT, PEDOT-co-FLU and PEDOT-co-DBFwere prepared and a system block with the general structure [(EDOT) n-(ThCO-NHAr) m ] can be proposed. These materials were characterized by infrared spectroscopy, thermogravimetry, ultravioletvisible absorption, photoluminescence, cyclic voltammetry, photophysical, electrochemical, spectroelectrochemical techniques and scanning electron microscopy. PEDOT-co-2NFT, PEDOT-co-FLU and PEDOTco-DBF showed higher thermal stability (˜50°C), more expanded electroactivity range and higher charge accumulation in comparison to PEDOT homopolymer. These new copolymers tailored by D-A approach present very intense emissions in the deep-red and near infrared regions, in solid state and in solution, and they may be applied as novel fluorophores for high efficient deep-red/NIR fluorescent devices.
Abstract The scarcity of studies concerning diestertin(IV) dithiocarbamate complexes led us to in... more Abstract The scarcity of studies concerning diestertin(IV) dithiocarbamate complexes led us to investigate the spectroscopic and structural properties of [(RO2CCH2CH2)2Sn(MDTC)2] (R = Me (1) or Et (2); MDTC = morpholinodithiocarbamate). The reaction of [(MeO2CCH2CH2)2SnCl2] with sodium morpholinodithiocarbamate (NaMDTC) in CHCl3 afforded (1), while the transesterification reaction of (1) with EtOH in the presence of dmso yielded (2). Both diestertin(IV) complexes were characterized by elemental analysis, FTIR and multinuclear (1H, 13C and 119Sn) NMR spectroscopy, and single-crystal X-ray diffraction. Our X-ray structural analysis revealed that (1) and (2) exhibit a distorted pentagonal bipyramidal coordination geometry. In both cases, the apical positions are occupied by ester groups while the equatorial plane displays two bidentate morpholinodithiocarbamate ligands and one intramolecular C O⋯Sn interaction. The O⋯Sn distances amount to 2.632 (1) and 2.618 A (2). According to our supramolecular analysis, the crystal arrangement of each product is assembled by weak C–H⋯O and C–H⋯S hydrogen bonds. Finally, a DFT study of the six- and seven-coordinate forms of (1) and (2) allowed an upper-bound estimate of the intramolecular C O⋯Sn interaction energy, −3.7 kcal mol−1.
reactions of dimethoxycarbonylethyltin-pyrrolidinodithiocarbamate, [Sn(PDTC) 2 (CH 2 CH 2 COOCH 3... more reactions of dimethoxycarbonylethyltin-pyrrolidinodithiocarbamate, [Sn(PDTC) 2 (CH 2 CH 2 COOCH 3) 2 ]-Spectroscopic and X-ray structural characterization of new estertin dithiocarbamate complexes-Part I,
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Design, structural and spectroscopic elucidation and in vitro antimicrobial, anticancer, antileishmanial, urease inhibition activities and interaction with SS-DNA of newly synthesized amide based carboxylic acid
Novel and barely accessible 1,2,3-triazoles with potential antitumoral activity were synthesized ... more Novel and barely accessible 1,2,3-triazoles with potential antitumoral activity were synthesized with good to moderate yields by a diazo-transfer process from 5,7-dinitro-3-diazo-l,3-dihydro-2H-indol-2-one to enaminones.
The reaction of ammonium pyrrolidinedithiocarbamate with SnPh2Cl2 and SnPh3Cl produced in good yi... more The reaction of ammonium pyrrolidinedithiocarbamate with SnPh2Cl2 and SnPh3Cl produced in good yield the compounds [Sn{S2CN(CH2)4}2{C6H5}2]·toluene (1) and Sn{S2CN(CH2)4}{C6H5}3 (2). They were fully characterised by multinuclear NMR [1H,13C{1H} and 119Sn{1H}] and 119Sn Mössbauer spectroscopies. In addition the structure of 1 was determined, and 2 was revised by X-ray crystallographic studies. Finally, thermal decomposition experiments were carried out for both compounds
Mn(iii)–porphyrin catalysts with electron-withdrawing substituents were designed to uncover elect... more Mn(iii)–porphyrin catalysts with electron-withdrawing substituents were designed to uncover electronic and structural aspects in the cycloaddition of CO2 with epoxides.
A Novel and Easy De-ethoxycarbonylation of α-Substituted Malonic Esters.-The title reaction is us... more A Novel and Easy De-ethoxycarbonylation of α-Substituted Malonic Esters.-The title reaction is used to convert various α-sulfonyl malonates, e.g. (III), and α-alkyl malonates, such as (VIII), into the corresponding monoesters like (IV) and (IX).-(MELO,
Some 2-phenylthio-para-substituted cyclohexanones with different oxidation states of sulfur atom ... more Some 2-phenylthio-para-substituted cyclohexanones with different oxidation states of sulfur atom were studied by systematic conformational search around C-S bonds using the parametric method 3 (PM3) Hamiltonian. The axial and equatorial regular chair conformations were subjected to calculations and each one produced three rotamers: ϩgauche (؉G), Ϫgauche (؊G), and anti (A). The axial conformations were more populated than the equatorial ones. The para-substituent and sulfur group effects over conformational populations and carbonyl polarizations suggest that the main electronic interaction between sulfur atom and carbonyl group are of repulsive nature in both axial (such as S ϩ C ϩ O) and equatorial (such as S Ϫ CO Ϫ) conformations. The axial ؉G conformation is the more stable for all compounds, except for (R 2 ,S S)-sulfinyl isomer, because it allows an attractive electrostatic interaction between CO and Sbond dipoles (such as S ϩ CO Ϫ). The axial A conformation is the more stable for (R 2 ,S S)-sulfinyl compounds, because the sulfinyl oxygen is at ϪG position near the carbonyl group and an attractive electrostatic interaction (such as O SO Ϫ C ϩ O) can take place. The higher carbonyl polarization and negative charge of carbon C-2 plus hydrogen H-2 of cyclohexanone ring for sulfonyl compared with sulfanyl and sulfinyl compounds, can be explained by a through-space interaction instead through-bond inductive effects.
Supplementary Material Available: Projections showing the molecular packing observed in the two m... more Supplementary Material Available: Projections showing the molecular packing observed in the two molecules, listings of observed and calculated structure amplitudes (XlO), and thermal parameters (32 pages). Ordering information is given on any current masthead page.
Methods for the development and validation for determination of iron and zinc in human serum and ... more Methods for the development and validation for determination of iron and zinc in human serum and hair samples by graphite furnace atomic absorption spectrometry (GF AAS) were performed. Solubilization was immediate by manual agitation in both samples with a 10 mL volume sample plus deionized water. Optimum pyrolysis and atomization temperatures were obtained by pyrolysis and atomization temperature curves in both matrices. For serum samples, the best temperatures were 1400 and 2500 °C (Fe) and 700 and 1600 °C (Zn), respectively. For hair samples, the best temperatures were 1000 and 2400 °C (Fe) and 800 and 1600 °C (Zn), respectively. Permanent modifiers and zirconium presented best the results for Zn in both matrices and for Fe in serum. Permanent modifier Nb was best for hair Zn. Serum and hair values were in agreement with the certified values for analytes and certified samples. The determined values for serum Fe and hair certified samples were 1.40 ± 0.2 and 114 ± 18 mg L-1 , respectively. For Zn certified reference materials (CRMs), the certified samples values were 1720 ± 32 µg L-1 and 172 ± 5 mg kg-1. Simple, accurate and precise, this method represents a cost-effective detection protocol suitable for sample analysis for diagnosis of micronutrient malnutrition.
Abstract The reactions of SnR2Cl2 (R = Me, Bu or Ph) with sodium 4-phenylbutyrate, NaO2C(CH2)3Ph ... more Abstract The reactions of SnR2Cl2 (R = Me, Bu or Ph) with sodium 4-phenylbutyrate, NaO2C(CH2)3Ph (NaOPhb), yielded three organotin carboxylates, namely [{(Me2SnOPhb)2O}2] (1), [Bu2Sn(OPhb)2] (2) and [{PhSn(O)OPhb}6] (3). Complexes (1) and (2) have been spectroscopically authenticated by FT-IR, 119Sn Mossbauer, and 1H, 13C{1H} and 119Sn{1H} NMR techniques. In addition, the crystallographic structures of (1)–(3) have been determined by X-ray diffraction measurements. Complex (1) displays two signals in the solution 119Sn NMR spectrum corresponding to the exo (δ −176.3) and endocyclic (δ −188.4) SnMe2 moieties, whereas (2) exhibits only one 119Sn resonance (δ −148.1). The crystallographic characterization of (1) confirms the centrosymmetric tetranuclear stannoxane structure and the existence of the exo and endocyclic SnMe2 moieties in the both distorted trigonal bipyramidal and octahedral environment, respectively. Complex (2) crystallises as a monomer in which the Sn(IV) cation lies at the centre of a distorted octahedron. The bonding scheme in (3) outlines a hexanuclear drum-like structure comprising two six-membered (–Sn–O–)3 stannoxane rings. The supramolecular arrangements of (1)–(3) result from noncovalent interactions, namely Sn⋯O (1) and (2), C–H⋯π (1), and C–H⋯O (1)–(3). Finally, antifungal activities of all organotin derivatives have been screened against Candida albicans (ATCC 18804), Candida tropicalis (ATCC 750), Candida glabrata (ATCC 90030), Candida parapsilosis (ATCC 22019), Candida lusitaniae (CBS 6936), and Candida dubliniensis (clinical isolate 28). Complex (2) exhibited the best biocide activity amongst the three organotin products.
This work reports the spectroelectrochemical and electrical behavior of electropolymerized donor-... more This work reports the spectroelectrochemical and electrical behavior of electropolymerized donor-acceptor like (D-A) copolymer films, based on 3,4-ethylenedioxythiophene (EDOT) and beta-substituted electron-acceptor thiophenes. Initially, the copolymer films were deposited on indium tin oxide substrates, which spectroelectrochemistry measurements were carried out with an UV-Vis spectrophotometer. Hence, it was possible to observe the electrochromic properties of these materials, visualizing the color changing towards different potentials applied. The experiments have shown that these D-A like copolymers presented good electrochromic properties, such as optical contrast, coloration efficiency, and switching times. Additionally, films prepared on a platinum working electrode were investigated by electrochemical impedance spectroscopy, which has shown the electrical behavior of those copolymers and their potential as candidates to capacitive devices building. Therefore, the combination of electron-donor EDOT with those electron-acceptor monomers is indeed a useful strategy to tailoring and fine-tuning the physicochemical properties of polythiophenes with innovative applications.
This work reports the preparation of two novel materials: a non-covalently bonded hybrid based on... more This work reports the preparation of two novel materials: a non-covalently bonded hybrid based on aminocarbazole-functionalized multi-walled carbon nanotube (MWCNTCO-NHCbz) and poly(3-dodecylthiophene) (P3DDT) and a covalently bonded nanohybrid based on MWCNT functionalized with 3,6-diamino-methylcarbazole (H 2 NCbzNH 2), 3-carboxythiophene (ThCOOH) and a final grafting of poly(3-hexylthiophene) (P3HT). These materials were characterized by several spectroscopic techniques that proved their successfully preparation. Beyond the thermal, electrochemical, electrical and morphological characterizations, thin films of both materials were also tested by spectroelectrochemical experiments. The covalently bonded material presented a better electrochromic performance when compared with the other material: optical contrast three times higher (6%); coloration efficiency of 10.8 C −1 cm 2 ; fast response times on the scale of few seconds; and greater longterm cyclability presenting a stable color changing memory and 73% of the original charge after 100 cycles. This enhanced performance might be related to the benefits provided by the covalent connections between the building blocks, such an important strategy of tailoring hybrid materials for multifunctional applications.
The rapid development in polymer chemistry has, in recent years, led to the introduction of polym... more The rapid development in polymer chemistry has, in recent years, led to the introduction of polymeric materials in the field of medicine. Two major groups of polymers are used for medical applications: prosthetic and biologically active materials. We synthesized copolymers with the main chain consisting of poly (methyl methacrylate) and graft chains of poly(ethylene glycol) (COP GRAFT). Changes were made in the graft copolymer chains for a possible incorporation of a drug, such that it may be used for the controlled release of drugs. The synthesis of these new compounds is based on two synthetic routes and FTIR, differential scanning calorimetry (DSC), thermogravimetry (TGA) and X-ray diffraction (XRD) characterized the products formed at the end of each stage. Through FTIR we observed absorption bands characteristic of P-H, P=O and P-O bonds that were inserted into the polymer chain during phosphorylation of the COP GRAFT, beyond the absorption bands characteristic of the copolymer before phosphorylation, such as C=O and CO. By TGA and DSC we observed that only the diisobutyl copolymer has endothermic transition temperature and degradation behavior consistent with a polymer. XRD results showed a structural and conformational change in crystallinity of modified chains. Molecular weight and polydispersity of COPGRAFT obtained by GPC increased after phosphorylation with diisobutyl group. The phosphorylation reaction was efficient in obtaining diisobutyl copolymer and the applied techniques confirmed the modification of the COPGRAFT chains.
Three new metal-free copolymeric fluorophores, which present unusual and strong fluorescence NIR ... more Three new metal-free copolymeric fluorophores, which present unusual and strong fluorescence NIR emission were synthesized through low-cost, easy, fast and efficient direct electropolymerization methodology without use of expensive catalysts or chemical coupling reactions. The tailoring of these novel more conjugated and polarized molecules was based on the Donor-Acceptor (D-A) approach. The three new designed binary molecular hybrids were obtained by direct oxidative electrocopolymerization with the well-known electron-donating (D) EDOT (3,4-ethylenedioxythiophene) and the electron-acceptor unit (A) ThCO-NHAr. This bis-functionalized molecular block was synthesized between the β-carboxythiophene (ThCO) with electron-donating and fluorescent aromatic amines (naphthylamine (NFT), aminofluorene (FLU) and aminodibenzofuran (DBF)). These monomers were submitted to copolymerization and three novel copolymers-PEDOT-co-2NFT, PEDOT-co-FLU and PEDOT-co-DBFwere prepared and a system block with the general structure [(EDOT) n-(ThCO-NHAr) m ] can be proposed. These materials were characterized by infrared spectroscopy, thermogravimetry, ultravioletvisible absorption, photoluminescence, cyclic voltammetry, photophysical, electrochemical, spectroelectrochemical techniques and scanning electron microscopy. PEDOT-co-2NFT, PEDOT-co-FLU and PEDOTco-DBF showed higher thermal stability (˜50°C), more expanded electroactivity range and higher charge accumulation in comparison to PEDOT homopolymer. These new copolymers tailored by D-A approach present very intense emissions in the deep-red and near infrared regions, in solid state and in solution, and they may be applied as novel fluorophores for high efficient deep-red/NIR fluorescent devices.
Abstract The scarcity of studies concerning diestertin(IV) dithiocarbamate complexes led us to in... more Abstract The scarcity of studies concerning diestertin(IV) dithiocarbamate complexes led us to investigate the spectroscopic and structural properties of [(RO2CCH2CH2)2Sn(MDTC)2] (R = Me (1) or Et (2); MDTC = morpholinodithiocarbamate). The reaction of [(MeO2CCH2CH2)2SnCl2] with sodium morpholinodithiocarbamate (NaMDTC) in CHCl3 afforded (1), while the transesterification reaction of (1) with EtOH in the presence of dmso yielded (2). Both diestertin(IV) complexes were characterized by elemental analysis, FTIR and multinuclear (1H, 13C and 119Sn) NMR spectroscopy, and single-crystal X-ray diffraction. Our X-ray structural analysis revealed that (1) and (2) exhibit a distorted pentagonal bipyramidal coordination geometry. In both cases, the apical positions are occupied by ester groups while the equatorial plane displays two bidentate morpholinodithiocarbamate ligands and one intramolecular C O⋯Sn interaction. The O⋯Sn distances amount to 2.632 (1) and 2.618 A (2). According to our supramolecular analysis, the crystal arrangement of each product is assembled by weak C–H⋯O and C–H⋯S hydrogen bonds. Finally, a DFT study of the six- and seven-coordinate forms of (1) and (2) allowed an upper-bound estimate of the intramolecular C O⋯Sn interaction energy, −3.7 kcal mol−1.
reactions of dimethoxycarbonylethyltin-pyrrolidinodithiocarbamate, [Sn(PDTC) 2 (CH 2 CH 2 COOCH 3... more reactions of dimethoxycarbonylethyltin-pyrrolidinodithiocarbamate, [Sn(PDTC) 2 (CH 2 CH 2 COOCH 3) 2 ]-Spectroscopic and X-ray structural characterization of new estertin dithiocarbamate complexes-Part I,
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Design, structural and spectroscopic elucidation and in vitro antimicrobial, anticancer, antileishmanial, urease inhibition activities and interaction with SS-DNA of newly synthesized amide based carboxylic acid
Novel and barely accessible 1,2,3-triazoles with potential antitumoral activity were synthesized ... more Novel and barely accessible 1,2,3-triazoles with potential antitumoral activity were synthesized with good to moderate yields by a diazo-transfer process from 5,7-dinitro-3-diazo-l,3-dihydro-2H-indol-2-one to enaminones.
The reaction of ammonium pyrrolidinedithiocarbamate with SnPh2Cl2 and SnPh3Cl produced in good yi... more The reaction of ammonium pyrrolidinedithiocarbamate with SnPh2Cl2 and SnPh3Cl produced in good yield the compounds [Sn{S2CN(CH2)4}2{C6H5}2]·toluene (1) and Sn{S2CN(CH2)4}{C6H5}3 (2). They were fully characterised by multinuclear NMR [1H,13C{1H} and 119Sn{1H}] and 119Sn Mössbauer spectroscopies. In addition the structure of 1 was determined, and 2 was revised by X-ray crystallographic studies. Finally, thermal decomposition experiments were carried out for both compounds
Mn(iii)–porphyrin catalysts with electron-withdrawing substituents were designed to uncover elect... more Mn(iii)–porphyrin catalysts with electron-withdrawing substituents were designed to uncover electronic and structural aspects in the cycloaddition of CO2 with epoxides.
A Novel and Easy De-ethoxycarbonylation of α-Substituted Malonic Esters.-The title reaction is us... more A Novel and Easy De-ethoxycarbonylation of α-Substituted Malonic Esters.-The title reaction is used to convert various α-sulfonyl malonates, e.g. (III), and α-alkyl malonates, such as (VIII), into the corresponding monoesters like (IV) and (IX).-(MELO,
Some 2-phenylthio-para-substituted cyclohexanones with different oxidation states of sulfur atom ... more Some 2-phenylthio-para-substituted cyclohexanones with different oxidation states of sulfur atom were studied by systematic conformational search around C-S bonds using the parametric method 3 (PM3) Hamiltonian. The axial and equatorial regular chair conformations were subjected to calculations and each one produced three rotamers: ϩgauche (؉G), Ϫgauche (؊G), and anti (A). The axial conformations were more populated than the equatorial ones. The para-substituent and sulfur group effects over conformational populations and carbonyl polarizations suggest that the main electronic interaction between sulfur atom and carbonyl group are of repulsive nature in both axial (such as S ϩ C ϩ O) and equatorial (such as S Ϫ CO Ϫ) conformations. The axial ؉G conformation is the more stable for all compounds, except for (R 2 ,S S)-sulfinyl isomer, because it allows an attractive electrostatic interaction between CO and Sbond dipoles (such as S ϩ CO Ϫ). The axial A conformation is the more stable for (R 2 ,S S)-sulfinyl compounds, because the sulfinyl oxygen is at ϪG position near the carbonyl group and an attractive electrostatic interaction (such as O SO Ϫ C ϩ O) can take place. The higher carbonyl polarization and negative charge of carbon C-2 plus hydrogen H-2 of cyclohexanone ring for sulfonyl compared with sulfanyl and sulfinyl compounds, can be explained by a through-space interaction instead through-bond inductive effects.
Supplementary Material Available: Projections showing the molecular packing observed in the two m... more Supplementary Material Available: Projections showing the molecular packing observed in the two molecules, listings of observed and calculated structure amplitudes (XlO), and thermal parameters (32 pages). Ordering information is given on any current masthead page.
Methods for the development and validation for determination of iron and zinc in human serum and ... more Methods for the development and validation for determination of iron and zinc in human serum and hair samples by graphite furnace atomic absorption spectrometry (GF AAS) were performed. Solubilization was immediate by manual agitation in both samples with a 10 mL volume sample plus deionized water. Optimum pyrolysis and atomization temperatures were obtained by pyrolysis and atomization temperature curves in both matrices. For serum samples, the best temperatures were 1400 and 2500 °C (Fe) and 700 and 1600 °C (Zn), respectively. For hair samples, the best temperatures were 1000 and 2400 °C (Fe) and 800 and 1600 °C (Zn), respectively. Permanent modifiers and zirconium presented best the results for Zn in both matrices and for Fe in serum. Permanent modifier Nb was best for hair Zn. Serum and hair values were in agreement with the certified values for analytes and certified samples. The determined values for serum Fe and hair certified samples were 1.40 ± 0.2 and 114 ± 18 mg L-1 , respectively. For Zn certified reference materials (CRMs), the certified samples values were 1720 ± 32 µg L-1 and 172 ± 5 mg kg-1. Simple, accurate and precise, this method represents a cost-effective detection protocol suitable for sample analysis for diagnosis of micronutrient malnutrition.
Abstract The reactions of SnR2Cl2 (R = Me, Bu or Ph) with sodium 4-phenylbutyrate, NaO2C(CH2)3Ph ... more Abstract The reactions of SnR2Cl2 (R = Me, Bu or Ph) with sodium 4-phenylbutyrate, NaO2C(CH2)3Ph (NaOPhb), yielded three organotin carboxylates, namely [{(Me2SnOPhb)2O}2] (1), [Bu2Sn(OPhb)2] (2) and [{PhSn(O)OPhb}6] (3). Complexes (1) and (2) have been spectroscopically authenticated by FT-IR, 119Sn Mossbauer, and 1H, 13C{1H} and 119Sn{1H} NMR techniques. In addition, the crystallographic structures of (1)–(3) have been determined by X-ray diffraction measurements. Complex (1) displays two signals in the solution 119Sn NMR spectrum corresponding to the exo (δ −176.3) and endocyclic (δ −188.4) SnMe2 moieties, whereas (2) exhibits only one 119Sn resonance (δ −148.1). The crystallographic characterization of (1) confirms the centrosymmetric tetranuclear stannoxane structure and the existence of the exo and endocyclic SnMe2 moieties in the both distorted trigonal bipyramidal and octahedral environment, respectively. Complex (2) crystallises as a monomer in which the Sn(IV) cation lies at the centre of a distorted octahedron. The bonding scheme in (3) outlines a hexanuclear drum-like structure comprising two six-membered (–Sn–O–)3 stannoxane rings. The supramolecular arrangements of (1)–(3) result from noncovalent interactions, namely Sn⋯O (1) and (2), C–H⋯π (1), and C–H⋯O (1)–(3). Finally, antifungal activities of all organotin derivatives have been screened against Candida albicans (ATCC 18804), Candida tropicalis (ATCC 750), Candida glabrata (ATCC 90030), Candida parapsilosis (ATCC 22019), Candida lusitaniae (CBS 6936), and Candida dubliniensis (clinical isolate 28). Complex (2) exhibited the best biocide activity amongst the three organotin products.
This work reports the spectroelectrochemical and electrical behavior of electropolymerized donor-... more This work reports the spectroelectrochemical and electrical behavior of electropolymerized donor-acceptor like (D-A) copolymer films, based on 3,4-ethylenedioxythiophene (EDOT) and beta-substituted electron-acceptor thiophenes. Initially, the copolymer films were deposited on indium tin oxide substrates, which spectroelectrochemistry measurements were carried out with an UV-Vis spectrophotometer. Hence, it was possible to observe the electrochromic properties of these materials, visualizing the color changing towards different potentials applied. The experiments have shown that these D-A like copolymers presented good electrochromic properties, such as optical contrast, coloration efficiency, and switching times. Additionally, films prepared on a platinum working electrode were investigated by electrochemical impedance spectroscopy, which has shown the electrical behavior of those copolymers and their potential as candidates to capacitive devices building. Therefore, the combination of electron-donor EDOT with those electron-acceptor monomers is indeed a useful strategy to tailoring and fine-tuning the physicochemical properties of polythiophenes with innovative applications.
This work reports the preparation of two novel materials: a non-covalently bonded hybrid based on... more This work reports the preparation of two novel materials: a non-covalently bonded hybrid based on aminocarbazole-functionalized multi-walled carbon nanotube (MWCNTCO-NHCbz) and poly(3-dodecylthiophene) (P3DDT) and a covalently bonded nanohybrid based on MWCNT functionalized with 3,6-diamino-methylcarbazole (H 2 NCbzNH 2), 3-carboxythiophene (ThCOOH) and a final grafting of poly(3-hexylthiophene) (P3HT). These materials were characterized by several spectroscopic techniques that proved their successfully preparation. Beyond the thermal, electrochemical, electrical and morphological characterizations, thin films of both materials were also tested by spectroelectrochemical experiments. The covalently bonded material presented a better electrochromic performance when compared with the other material: optical contrast three times higher (6%); coloration efficiency of 10.8 C −1 cm 2 ; fast response times on the scale of few seconds; and greater longterm cyclability presenting a stable color changing memory and 73% of the original charge after 100 cycles. This enhanced performance might be related to the benefits provided by the covalent connections between the building blocks, such an important strategy of tailoring hybrid materials for multifunctional applications.
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