Antonio Frontera
Universidad de las Islas Baleares, Chemistry, Faculty Member
Abstract Compounds incorporating elements belonging to groups 14–18 as electron-deficient sites are capable to establish directional interactions with a variety of Lewis bases (e.g., lone pairs, π-clouds, anions). These noncovalent... more
Abstract Compounds incorporating elements belonging to groups 14–18 as electron-deficient sites are capable to establish directional interactions with a variety of Lewis bases (e.g., lone pairs, π-clouds, anions). These noncovalent interactions are usually named as σ/π-hole tetrel (group 14), pnictogen (group 15), chalcogen (group 16), halogen (group 17), and noble gas (or aerogen) bonding (group 18). In general, σ/π-hole interactions offer differentiating energetic and geometric features, and we focus on σ-hole interactions. The differentiating features depend first and foremost on the group and row of the Periodic Table that the element belongs to and can be tuned by its chemical context. This chapter combines insights from theory with solid-state structure evidence to emphasize the similarities and differences among tetrel, pnictogen, chalcogen, halogen, and noble gas bonding σ-hole interactions.
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ABSTRACT We report the synthesis and X-ray characterization of N9- and N6-decyladenine hydrochloride salts. The latter exhibits interesting anion–π interactions, which are responsible for crystal packing. In contrast, the former does not... more
ABSTRACT We report the synthesis and X-ray characterization of N9- and N6-decyladenine hydrochloride salts. The latter exhibits interesting anion–π interactions, which are responsible for crystal packing. In contrast, the former does not present any anion–π interactions; the anion is stabilized by hydrogen-bonding interactions. Finally, a theoretical study of the different binding modes observed in the solid state is useful to explain the experimental findings.
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The cover picture shows the interesting anion–π/π–π/anion–π assembly that is found in the solid‐state architecture of an adenine derivative hydrochloride salt. The adenine has been decorated with a long alkyl chain (C10) in order to have... more
The cover picture shows the interesting anion–π/π–π/anion–π assembly that is found in the solid‐state architecture of an adenine derivative hydrochloride salt. The adenine has been decorated with a long alkyl chain (C10) in order to have a predefined ordering in the crystal due to hydrophobic effects. The influence of anion–π and π–π interactions on the final structure has been studied both experimentally and theoretically. Details are discussed in the article by A. Garcia‐Raso et al. on p. 5171 ff. The background picture depicts the scientific tradition of the Balearic Islands that springs from Ramon Llull, a 13th century philosopher, who founded a college in Miramar that is located in the northwest of the island of Majorca.
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Two Zn(II) coordination polymers, viz., [Zn2Cl2(H2O)2(µ-4-AmBz)2]n (1) and [ZnCl2(µ-3-AmPy)2]n (2) (4-AmBz = 4-aminobenzoate, 3-AmPy = 3-aminopyridine) have been prepared at room temperature and characterized using elemental analysis,... more
Two Zn(II) coordination polymers, viz., [Zn2Cl2(H2O)2(µ-4-AmBz)2]n (1) and [ZnCl2(µ-3-AmPy)2]n (2) (4-AmBz = 4-aminobenzoate, 3-AmPy = 3-aminopyridine) have been prepared at room temperature and characterized using elemental analysis, FT-IR, electronic spectroscopy, TGA (thermogravimetric analysis) and single crystal XRD. Crystal structure analyses of the polymers unfold the presence of non-covalent anion–π, π-stacking and unusual NH2(amino)⋯π interactions which provide rigidity to the crystal structures. Unconventional Type I Cl⋯Cl interactions also play a pivotal role in the stability of compound 1. Molecular electrostatic potential (MEP) surface analysis reveals that the MEP values over the center of the aromatic rings of coordinated 4-AmBz and 3-AmPy moieties are positive on one side and negative on the other side which confirms the dual non-covalent donor-acceptor topologies of the aromatic rings and explains the concurrent formation of unusual non-covalent NH2···π and anion–π ...
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In vitro anticancer activities have been explored in fumarato and phthalato bridged dinuclear Cu(ii) and Mn(ii) compounds involving infinite fumarate–water assemblies and unusual structure-guiding H-bonded synthons.
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Anticancer activities considering cell cytotoxicity, apoptosis and molecular docking have been explored in Zn(ii) co-crystals of phenanthroline involving infinite chair-like assemblies and unconventional layered infinite anion-water... more
Anticancer activities considering cell cytotoxicity, apoptosis and molecular docking have been explored in Zn(ii) co-crystals of phenanthroline involving infinite chair-like assemblies and unconventional layered infinite anion-water clusters.
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Anticancer activities considering cell viability, apoptosis and molecular docking have been explored in dinuclear Zn(ii) and polymeric Mn(ii) compounds involving energetically significant unconventional N(nitrile)⋯π(fum) contacts.
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Abstract Two new coordination compounds viz. [Ni(2,6-PDC)(Hdmpz)(H2O)2]∙H2O (1) and [Zn(3-CNpy)2Cl2] (2) (2,6-PDC = 2,6-pyridinedicarboxylate, Hdmpz = 3,5-dimethylpyrazole, 3-CNpy = 3-cyanopyridine) have been synthesized and characterized... more
Abstract Two new coordination compounds viz. [Ni(2,6-PDC)(Hdmpz)(H2O)2]∙H2O (1) and [Zn(3-CNpy)2Cl2] (2) (2,6-PDC = 2,6-pyridinedicarboxylate, Hdmpz = 3,5-dimethylpyrazole, 3-CNpy = 3-cyanopyridine) have been synthesized and characterized using elemental analysis, thermogravimetric analysis, electronic, infrared spectroscopy and single crystal X-ray diffraction techniques. Crystal structure analyses reveal the presence of supramolecular assemblies involving interesting dimers with unconventional contacts in the compounds. DFT (Density Functional Theory) calculations on the supramolecular dimers in the crystal structure of 1 reveal that the sum of contributions of anion–π, π–π and other long range interactions due to the approximation of the bulk monomers is energetically significant. Molecular Electrostatic Potential (MEP) surface and Quantum Theory of Atoms in Molecules (QTAIM) analyses on the interesting supramolecular dimers of the crystal structures of 2 reveal the presence of unconventional anion⋯π contacts involving coordinated chlorido ligands and C–H⋯π(nitrile) interactions involving the π-system of the nitrile moiety of 3-cyanopyridine. Remarkably, Atoms in Molecules analysis also confirms the existence of energetically significant unconventional anti-parallel nitrile⋯nitrile interaction in the crystal structure of 2. Cell cytotoxicity of the compounds performed in Dalton's lymphoma (DL) malignant cancer cell line showed effective potency with negligible cytotoxicity in normal cells (~12%). It is interesting that compound 1has excellent cytotoxic potency with IC50 closer to cisplatin and can bind different biological targets with similar signalling pathways. Structure activity relationship (SAR) analyses of 1 and 2 based on pharmacophore modelling reveal that the molecular features associated with the structures of the compounds play important role in the biological activities.
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In vitro anticancer activities have been explored in solvent driven maleato and fumarato bridged Zn(ii) coordination polymers involving energetically significant antiparallel π-stacking and enclathrated guest MeOH/H2O moieties.
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Abstract Two pyridinedicarboxylato bridged 1D coordination polymers of copper(II) viz.; {[Cu(2,5-PDC)(Hdmpz)2]·H2O}n (1) and {[Cu(2,3-PDC)]·10H2O}n (2) (where, Hdmpz = 3,5-dimethyl pyrazole, PDC = pyridinedicarboxylate) have been isolated... more
Abstract Two pyridinedicarboxylato bridged 1D coordination polymers of copper(II) viz.; {[Cu(2,5-PDC)(Hdmpz)2]·H2O}n (1) and {[Cu(2,3-PDC)]·10H2O}n (2) (where, Hdmpz = 3,5-dimethyl pyrazole, PDC = pyridinedicarboxylate) have been isolated and characterized using TGA, elemental analysis, spectroscopic (IR, electronic) and single crystal X-ray diffraction techniques. Crystal structure analysis of the compounds 1 and 2 reveals that unconventional C–H⋯π(carbonyl) and intramolecular O⋯C π-hole interactions provide stability to the crystal structures, respectively. Such C–H⋯π(carbonyl) and intramolecular O⋯C π-hole interactions are scarcely reported in the literature. Theoretical calculations have been performed to analyze the unconventional non-covalent interactions observed in the solid-state structures of 1 and 2 using NCI plot and QTAIM computational tools. We have also theoretically explored the semi-coordination (regium) Cu-Oaxial bonds present in the compound 2. The polymers have been further investigated for potential antiproliferative activities considering cell viability and apoptosis assays against Dalton’s lymphoma (DL) cancer cell lines and the results were compared with cisplatin (reference drug) in the same experimental conditions. The compounds significantly induce cytotoxicity in DL cells with nominal cytotoxicity in normal PBMC cells. The molecular doking simulation performed with the antiapoprotic protiens reveals strong binding affinities of the compounds with the active sites of the target proteins. To establish structure activity relationship (SAR), pharmacophore studies have been carried out to investigate the key pharmacophore features of the structures of the compounds responsible for biological activities.
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The ability of Triangulenium (TA+) compounds to form Frustrated Lewis Pairs (FLPs) with N‐HeteroCycle Carbenes (NHCs) is analysed in this manuscript at the PBE0‐D3/def2‐TZVP level of theory. We have used six TA+‐based moieties, three... more
The ability of Triangulenium (TA+) compounds to form Frustrated Lewis Pairs (FLPs) with N‐HeteroCycle Carbenes (NHCs) is analysed in this manuscript at the PBE0‐D3/def2‐TZVP level of theory. We have used six TA+‐based moieties, three presenting similar bridging groups (O (trioxo), −CH2(triaryl) and −NH (triaza)) and another three mixing, O, −CH2and NH moieties. In addition, several aryl‐substituted NHCs have been used as electron donor moieties to undergo carbon⋅⋅⋅carbon+tetrel bonds with the TA+derivatives. More precisely, −Me,−iPr, −tBu and −Ph groups were used. Finally, we have used Bader's quantum theory of “atoms in molecules” (QTAIM) and Natural Bonding Analysis (NBO) to characterize the carbon⋅⋅⋅carbon+tetrel bonds described herein. We expect the results gathered herein will be useful for further exploitation of carbon⋅⋅⋅carbon+bonds in the formation of FLPs as well as to expand the current knowledge of tetrel bonds to the fields of synthetic chemistry and catalysis.
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Cytotoxicity in cancer cells with structure activity relationship has been explored in Cu(ii) compounds involving biologically relevant cooperative assemblies and fascinating crown-like nitrate–water hosts with guest complex cations.
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Abstract Two new coordination compounds viz. [Ni(phen)2(NO3)](NO3)•4H2O (1) and [Ni(phen)2(H2O)Cl]Cl•4H2O (2) (phen = 1,10-phenanthroline) have been synthesized and characterized using elemental analysis, TGA, PXRD, electronic, FT-IR... more
Abstract Two new coordination compounds viz. [Ni(phen)2(NO3)](NO3)•4H2O (1) and [Ni(phen)2(H2O)Cl]Cl•4H2O (2) (phen = 1,10-phenanthroline) have been synthesized and characterized using elemental analysis, TGA, PXRD, electronic, FT-IR spectroscopy and single crystal X-ray diffraction techniques. Crystal structure analysis reveals the formation of discrete water and anion-water clusters that contribute to the layered assemblies of the compounds. Moreover, the enclathration of (H2O)4 cluster in the layered assembly of 2 also provides rigidity to the crystal structure. Unconventional anion-π interaction is also observed in compound 1 involving the π-system of the chelate ring of coordinated phen. Detailed structural investigation reveals the presence of biologically relevant cooperative π-stacked (π–π)1/(π–π)2/(π–π)1 ternary assemblies in both the compounds. Interestingly, DFT calculations reveal that (π-π)2 binding mode in 2 is energetically significant than in compound 1 which is further analyzed by NCI plot index computational tool. The compounds have been screened for anticancer activities considering cell cytotoxicity and apoptosis in Dalton's lymphoma (DL) malignant cancer cell line. The complexes significantly inhibit cell viability by inducing apoptotic cell death in cancer cell lines with negligible cytotoxicity in normal cells. DNA ladder assay results in the degradation of genomic DNA into small inter-nucleosomal fragments (damage DNA) which is a biochemical hallmark of DL cells undergoing apoptosis. Lactate dehydrogenase (LDH) leakage assay also reveals the release of the intracellular enzyme LDH from DL cells indicating the irreversible cell death involving cell membrane damage. The molecular docking simulations reveal that the compounds interact and accommodated well with the active site of anti-apoptotic BCL proteins. Structure activity relationship (SAR) analysis based on pharmacophore modelling reveal that the molecular features of the compounds play important roles in the biological activities.
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Abstract Two new Ni(II) coordination complexes involving fumarate and 1,10-phenathroline viz.; [Ni2(phen)2(μ-fum)(H2O)6](fum)•6H2O (1) and [Ni(phen)2(H2O)2](0.5 fum)(NO3)•4H2O (2) (fum = fumarate, phen = 1,10-phenanthroline) have been... more
Abstract Two new Ni(II) coordination complexes involving fumarate and 1,10-phenathroline viz.; [Ni2(phen)2(μ-fum)(H2O)6](fum)•6H2O (1) and [Ni(phen)2(H2O)2](0.5 fum)(NO3)•4H2O (2) (fum = fumarate, phen = 1,10-phenanthroline) have been isolated in aqueous medium at room temperature. Crystal structure analyses of the compounds reveal the presence of cooperative (π–π)2/(π–π)1/(π–π)2 stacked ternary assemblies which provide stabilities to the layered architectures. The lattice water and the large counter anions in the lattice of the compounds are involved in the formation of unconventional discrete cyclic fumarate-water, fumarate-water-nitrate clusters and infinite nitrate-water 1D chains that are very scarcely reported in the literature. The energetically significant π-stacked dimers observed in the biologically relevant ternary assemblies of the crystal structures are further studied theoretically using DFT calculations and NCI plot index computational tools. DFT calculations reveal that the cooperative (π–π)2 binding mode of compound 1 is energetically more significant than (π–π)1 Moreover, the study also reveals that for the equivalent cooperative (π–π)1 stacking interactions in both the structures, the energy is unexpectedly higher for compound 2 than that observed for compound 1. Both the compounds induce significant cytotoxicity in Dalton's lymphoma (DL) cancer cells by inducing apoptotic cell death with negligible cytotoxicity in normal cells. Decrease in the mitochondrial membrane potential (MMP) of DL cells after treatment with the compounds also corroborates the apoptotic cell death. The molecular docking and pharmacophore features reveal that the compounds interact and accommodated well with the active sites of anti-apoptotic proteins.
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Novel adipato bridged Cu(ii) and Co(ii) complexes synthesized by considering cytotoxicity, apoptosis, ROS generation, molecular docking and pharmacophore features.
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A novel approach to modify the SBU of bio-MOF-1 by reducing the nuclearity of the metal cluster while retaining the topology of the anionic 3D framework is reported.
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Abstract A new coordination polymer of nickel(II) involving bridging fumarato viz. catena[μ-fumarato(1,10-phenanthroline monohydrate(diaqua))nickel(II)trihydrate], {[Ni(μ-fum)(phen)(H2O)2].3H2O}n (1) (where, fum = fumarate,... more
Abstract A new coordination polymer of nickel(II) involving bridging fumarato viz. catena[μ-fumarato(1,10-phenanthroline monohydrate(diaqua))nickel(II)trihydrate], {[Ni(μ-fum)(phen)(H2O)2].3H2O}n (1) (where, fum = fumarate, phen = 1,10-phenanthroline monohydrate) has been synthesized in purely aqueous medium at room temperature. The crystal structure of the polymer has been determined by single crystal X-ray Diffraction analysis. The polymer has been characterised by FT-IR, electronic spectroscopy, thermal and elemental analysis. The zig-zag polymeric chain of 1 self assembles into 2D supramolecular network architecture via reciprocal π-π stacking interactions. The lattice water molecules are involved in the formation of unique supramolecular octameric linear water clusters involving alternate trimeric rings that stabilizes the 2D network architecture. The crystal structure of the polymer also reveals the self-assembled enclathration of (H2O)8 cluster into polymeric Ni(II) host involving fum ligands that brings rigidity to the structure. Theoretical calculations have been performed to analyse the non-covalent interactions observed in the solid-state structure of 1. In particular, we have analysed the π–π stacking interactions between the phen ligands and also the energetically significant unconventional O H⋯π interaction involving the π-system of fum. For the latter, we have investigated the ability of the double bond of fum (coordinated to Ni) to establish O H⋯π interaction with water in comparison to fum acid and simple ethene. Finally, the polymer has been investigated for potential anticancer activities considering cell cytotoxicity, apoptosis and molecular docking as a major parameters against Dalton’s lymphoma (DL) malignant cancer cell line and the results were compared with cisplatin (reference drug) under the same experimental conditions. DNA interaction and fragmentations have been investigated for compound 1 and pharmacophore features establish structure activity relationship (SAR).
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H-Bonding networks and anion–π interactions in the crystal structures of N6-modified-amino acid adenine analogs are investigated using X-ray crystallography and DFT calculations.
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The interplay between two important noncovalent interactions involving aromatic rings is studied by means of high level ab initio calculations. They demonstrate that synergistic effects are present in complexes where anion-π and hydrogen... more
The interplay between two important noncovalent interactions involving aromatic rings is studied by means of high level ab initio calculations. They demonstrate that synergistic effects are present in complexes where anion-π and hydrogen bonding interactions coexist. These synergistic effects have been studied using the “atoms-in- molecules” theory and the Molecular Interaction Potential with polarization partition scheme. The present study examines how these two interactions mutually influence each other.
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... 404K). Keywords: carbohydrates; hexopyranoses; conformational analysis; ab initio;force field. Abstract. The OPLS all-atom (AA) force field for organic and biomolecular systems has been expanded to include carbohydrates. ...
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A new supramolecular Pb(II) complex [PbL(NO2)]n was synthesized from Pb(NO3)2, N’-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and NaNO2. [PbL(NO2)]n is constructed from discrete [PbL(NO2)] units with an almost ideal N2O3 square... more
A new supramolecular Pb(II) complex [PbL(NO2)]n was synthesized from Pb(NO3)2, N’-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and NaNO2. [PbL(NO2)]n is constructed from discrete [PbL(NO2)] units with an almost ideal N2O3 square pyramidal coordination environment around Pb(II). The ligand L− is coordinated through the 2-pyridyl N-atom, one aza N-atom, and the carbonyl O-atom. The nitrite ligand binds in a κ2-O,O coordination mode through both O-atoms. The Pb(II) center exhibits a hemidirected coordination geometry with a pronounced coordination gap, which allows a close approach of two additional N-atoms arising from the N=C(O) N-atom of an adjacent molecule and from the 4-pyridyl N-atom from the another adjacent molecule, yielding a N4O3 coordination, constructed from two Pb–N and three Pb–O covalent bonds, and two Pb⋯N tetrel bonds. Dimeric units in the structure of [PbL(NO2)]n are formed by the Pb⋯N=C(O) tetrel bonds and intermolecular electrostatically enforced π+⋯π− st...
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Regium–π interactions in biology and supramolecular chemistry.
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The cover picture shows the X‐ray structure of the N,N′‐tetramethylenebis(2‐aminopyrimidinium) tetrafluoroborate salt, which exhibits interesting anion–π interactions that are responsible for the crystal packing. The anion forms a... more
The cover picture shows the X‐ray structure of the N,N′‐tetramethylenebis(2‐aminopyrimidinium) tetrafluoroborate salt, which exhibits interesting anion–π interactions that are responsible for the crystal packing. The anion forms a sandwich complex with two pyrimidine rings. A schematic representation of the interaction is depicted in the upper left‐hand corner, which corresponds to the thermal ellipsoid plot. In the manuscript we include a theoretical study of the anion–π interaction involving charged pyrimidine rings, which is in good agreement with the findings of the experimental study. Details are discussed in the article by A. Garcia‐Raso, A. Frontera, P. M. Deyá et al. on p. 5821 ff.
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We report the synthesis and X‐ray characterization of an N,N′‐tetramethylenebis(2‐aminopyrimidinium) tetrafluoroborate salt that exhibits anion–π interactions that are responsible for the crystal packing. The anion forms a sandwich... more
We report the synthesis and X‐ray characterization of an N,N′‐tetramethylenebis(2‐aminopyrimidinium) tetrafluoroborate salt that exhibits anion–π interactions that are responsible for the crystal packing. The anion forms a sandwich complex with two pyrimidine rings. When the anion is nitrate, the crystal packing is governed by anion–π interactions and hydrogen bonds, and the sandwich complex is not formed. Finally, a theoretical study of the anion–π interactions in charged pyrimidine rings is in good agreement with the experimental findings. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
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Two coordination compounds of Cu(II), namely, [Cu (phen)2Cl](NO3)·H2O (compound 1) and [Cu2(µ-Cl2)Cl2(Hdmpz)4] (compound 2), where phen = 1,10-phenanthroline and Hdmpz = 3,5-dimethylpyrazole, were synthesized at room temperature and... more
Two coordination compounds of Cu(II), namely, [Cu (phen)2Cl](NO3)·H2O (compound 1) and [Cu2(µ-Cl2)Cl2(Hdmpz)4] (compound 2), where phen = 1,10-phenanthroline and Hdmpz = 3,5-dimethylpyrazole, were synthesized at room temperature and characterized using elemental analysis, TGA, spectroscopic techniques (FT-IR and electronic) and single-crystal X-ray diffraction studies. The cooperative anion–π/π–π/anion–π assemblies involving the coordinated phen, along with the uncoordinated nitrate moieties, played pivotal roles in the stabilization of the crystal structure of compound 1. Unconventional type I Cl⋯Cl interactions involving the coordinated Cl atoms provided reinforcement to the crystal structure of compound 2. We theoretically explored the supramolecular assemblies observed in the crystal structures of compounds 1 and 2 using DFT calculations, MEP surface analysis and combined NCI plot/QTAIM computational tools. Theoretical analysis revealed that the antiparallel π-stacking interacti...
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Two new Ni(II) and Co(II) coordination compounds, viz., [Ni(H2O)5(DMAP)](IPhth)·2H2O (1) and [Co(Hdmpz)4(H2O)2]Cl2 (2) (where DMAP = 4-dimethylaminopyridine, IPhth = Isophthalate, Hdmpz = 3,5-dimethylpyrazole),were synthesized and... more
Two new Ni(II) and Co(II) coordination compounds, viz., [Ni(H2O)5(DMAP)](IPhth)·2H2O (1) and [Co(Hdmpz)4(H2O)2]Cl2 (2) (where DMAP = 4-dimethylaminopyridine, IPhth = Isophthalate, Hdmpz = 3,5-dimethylpyrazole),were synthesized and characterized using elemental analysis, TGA, spectroscopic (FTIR and electronic) and single-crystal X-ray diffraction techniques. Compound 1 crystallizes as a co-crystal hydrate of Ni(II), whereas compound 2 is a mononuclear compound of Co(II). The crystal structure analysis of compound 1 reveals the presence of various non-covalent interactions such as anion–π, π–π, C–H∙∙∙π, C–H∙∙∙C, etc., which stabilize the layered assembly of the compound. In compound 2, enclathration of counter chloride ions within the supramolecular trimeric host cavity plays a crucial role in the stabilization of the compound. The non-covalent interactions observed in the crystal structures were further studied theoretically, focusing on the cooperative π-stacking interactions betwe...
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H-bonding networks and π–π and anion–π interactions in crystal structures of N-modified-amino acid pyrimidine analogs are investigated by means of DFT calculations and X-ray crystallography analysis.
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Six new multicomponent solids of 9-ethyladenine and oxalic acid have been detected and characterized. The salt screening has been performed by mechanochemical and solvent crystallization processes. Single crystals of the anhydrous salts... more
Six new multicomponent solids of 9-ethyladenine and oxalic acid have been detected and characterized. The salt screening has been performed by mechanochemical and solvent crystallization processes. Single crystals of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer molar ratio were obtained by solution crystallization and elucidated by single-crystal X-ray analysis. The supramolecular interactions observed in these solids have been studied using density functional theory (DFT) calculations and characterized by the quantum theory of “atoms in molecules” (QTAIM) and the noncovalent interaction plot (NCIPlot) index methods. The energies of the H-bonding networks observed in the solid state of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer are reported, disclosing the strong nature of the charge assisted NH···O hydrogen bonds and also the relative importance of ancillary C–H··O H-bonds.
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Related Article: Andres Tasada,Francisca M. Alberti,Antonio Bauza,Miquel Barcelo-Oliver,Angel Garcia-Raso,Juan J. Fiol,Elies Molins,Amparo Caubet,Antonio Frontera|2013|Chem.Commun.|49|4944|doi:10.1039/c3cc40772a
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H-Bonding networks and π–π and halogen bonding interactions in the crystal structures of N-modified amino acid pyrimidine analogs are investigated using DFT calculations and X-ray crystallography analysis.
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Among non-covalent interactions, halogen bonding is emerging as a new powerful tool for supramolecular self-assembly. Here, along with a green and effective method, we report three new halogen-bonded cocrystals containing uracil... more
Among non-covalent interactions, halogen bonding is emerging as a new powerful tool for supramolecular self-assembly. Here, along with a green and effective method, we report three new halogen-bonded cocrystals containing uracil derivatives and 1,2,4,5-tetrafluoro-3,6-diiodobenzene as X-bond donor coformer. These multicomponent solids were prepared both by solvent-drop grinding and solution methods and further characterized by powder and single-crystal X-ray diffraction, Fourier-transformed infrared spectroscopy, and thermal methods (TGA-DSC). In order to study the relative importance of hydrogen versus halogen bonds in the crystal packing, computational methods were applied.
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Abstract Two Ni(II) and Cu(II) coordination compounds viz. [Ni(phen)3](0.5adp)(2NO3)·4.5H2O (1) and [Cu4(phen)4(H2O)2(OH)4]4NO3·2H2O (2) (where, phen = 1,10-phenanthroline and adp = adipic acid) have been isolated in aqueous medium and... more
Abstract Two Ni(II) and Cu(II) coordination compounds viz. [Ni(phen)3](0.5adp)(2NO3)·4.5H2O (1) and [Cu4(phen)4(H2O)2(OH)4]4NO3·2H2O (2) (where, phen = 1,10-phenanthroline and adp = adipic acid) have been isolated in aqueous medium and characterized by single crystal XRD, TGA, elemental analysis and spectroscopic techniques (FT-IR and electronic). Crystal structure analysis of compound 1 reveals the unconventional enclathration of adp moieties in the tetrameric supramolecular host cavities via O(adp)···π and C–H···π interactions. The formation of discrete [(NO3)4(H2O)10]4− cores in 1 and unusual enclathration of the nitrate water clusters in the supramolecular host cavity of 2 provide additional reinforcement to the layered assemblies. DFT calculations and NCI plot computational tools have been employed to investigate the energetically significant enclathrated adp moieties in supramolecular host cavities of 1 and the antiparallel π-stacked ternary assemblies involving regium-π(chelate) interaction in 2. To the best of our knowledge, this is the first report of enclathration of adipic acid, a long chain aliphatic dicarboxylic acid; and non-covalent regium-π bonding interaction involving chelate ring in metal organic compounds. Finally, the compounds have been screened for in vitro antiproliferative activities in Dalton's Lymphoma (DL) cancer cell lines considering cell cytotoxicity, apoptosis and molecular docking. The compounds exhibit considerable cytotoxicity in DL cells with nominal effects in healthy normal PBMC cells. The docking study reveals the effective binding affinity of the compounds with the active sites of BCL family antiapoptotic proteins.
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Abstract Two new benzoato bridged Mn(II) and Cu(II) dinuclear coordination compounds viz. [Mn2(bipy)2(4-Clbz)2(H2O)4]2(4-Clbz) (1) and [Cu2(bz)4(2-MePy)2] (2) (bipy = 2,2-bipyridine, 4-Clbz = 4-chlorobenzoate, bz = benzoate,... more
Abstract Two new benzoato bridged Mn(II) and Cu(II) dinuclear coordination compounds viz. [Mn2(bipy)2(4-Clbz)2(H2O)4]2(4-Clbz) (1) and [Cu2(bz)4(2-MePy)2] (2) (bipy = 2,2-bipyridine, 4-Clbz = 4-chlorobenzoate, bz = benzoate, 2-MePy = 2-methylpyridine) have been synthesized and characterized using elemental analysis, TGA, spectroscopic (FTIR, electronic, EPR) and single crystal X-ray diffraction techniques. Crystal structure analysis of compound 1 reveals the enclathration of guest 4-Clbz moiety in the supramolecular host tetramer which provides rigidity to the crystal structure. Further analysis reveals the presence of cooperative (π–π)2/(π–π)1/(π–π)2 ternary assemblies involving alternate coordinated and uncoordinated 4-Clbz moieties. In compound 2, intermolecular C H∙∙∙O, C H∙∙∙π and C H∙∙∙C contacts are involved in the formation of dimeric paddle wheel supramolecular assemblies which stabilizes the layered architecture. The cooperative interplay of H-bonding and π-stacked ternary assemblies of 1 has been studied theoretically using DFT calculations, MEP surface and NCI Plot computational tools. The large interaction energies along with the NCI plot index analysis confirm that the π-stacking assemblies in combination with the H-bonds are strong binding motifs. In vitro anticancer activity of the compounds considering cytotoxicity and apoptosis assays reveal significant concentration dependent cytotoxicity in Dalton's lymphoma (DL) cancer cell lines with nominal effects in normal healthy PBMC cells. Molecular docking study reveals the efficient interaction of the compounds with the antiapoptotic BCL family target proteins.
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We report the first gold(iii) complex with a cytosine derivative since 35 years. In the crystal structure, the complex stacks by reciprocal regium-bonding interactions. These interactions appear to be common in the Cambridge structure... more
We report the first gold(iii) complex with a cytosine derivative since 35 years. In the crystal structure, the complex stacks by reciprocal regium-bonding interactions. These interactions appear to be common in the Cambridge structure database.
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A binuclear and a tetranuclear zinc(ii) of pyruvaldehyde thiosemicarbazone show selective sensing of ATP at pH 7.4 (0.01 M HEPES) in CH3CN–H2O (9 : 1) medium. The DNA binding and phosphatase activities of the complexes are also reported.
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H-bonding networks, anion–π and π–π interactions in the crystal structures of N6-modified-amino acid adenine analogs are investigated by means of DFT calculations and X-ray crystallography analysis.