Search

The Strandberg polyoxometalate (POM) metallogel Na4(H3O)2[(O2CC2H4PO3)2Mo5O15] (1) was synthesized in which the Strandberg cluster is functionalized by phosphonocarboxylate. The POM gel shows reversible sol to gel transition and gel to gel transition. The multiphase visual transitions between three states as a function of temperature and solvent are scarcely reported. The gel is characterized by temperature‐dependent and frequency‐dependent rheological studies and corresponding xerogels were characterized by FT‐IR, PXRD, FE‐SEM, EDX, TEM, and 31P NMR techniques. The stabilization of gel or obtaining single crystals from the same reaction mixture can be tuned by choice of counter cation. The single crystals of compound Cs14[(HO2CC2H4PO3)2Mo5O15]3·2Cl·10H2O (2) are obtained on addition of CsCl to compound 1 reaction mixture. Compound 2 is characterized by single crystal X‐ray diffraction. The compound 2 crystallizes in I2/a space group with unit cell parameters of a = 24.2415(16) Å, b = 10.4542(6) Å, c = 42.687(3) Å, α = 90°, β = 94.791°(3), and γ = 90°. [ABSTRACT FROM AUTHOR]

We report a novel series of chiral monometallic dithiocarbamate complexes with pendant phenolic groups, formulated as [M{κ2S^S-S2CN(CH2PhOH)(CH(S-CH3))(NaPh)}2] (M = Ni(II) S,S-1, Cu(II) S,S-2, Zn(II) S,S-3) and [M{κ2S^S-S2CN(CH2PhOH)(CH(R-CH3))(NaPh)}2] (M = Ni(II) R,R-4, Cu(II) R,R-5, Zn(II) R,R-6). These compounds were synthesized through a process involving chiral amino precursors S-HL1, R-HL2, CS2 and the corresponding metal acetates. All the compounds have been characterized by microanalysis and standard spectroscopic methods such as 1H and 13C{1H}NMR, IR, UV-visible absorption and EPR spectroscopy. The spectral data suggest a square planar coordination geometry around the nickel(II) and copper(II) centers and a tetrahedral coordination geometry around zinc(II), which is corroborated by density functional theory calculations. The unprecedented molecular structures of imine precursors S-I, R-I and Ni(II)-dithiocarbamate complex S,S-1 were elucidated by single crystal X-ray diffraction (SCXRD), and their crystal packing patterns were studied. Evidently, the change in chirality could not induce changes in the donor–acceptor sites of S-I and R-I, and their molecules are primarily stabilized by O–H⋯N and C–H⋯π interactions, forming a 2D sheet-like structure in the ab-plane. Notably, the chiral S,S-1 complex crystallized in a monomeric achiral space group (triclinic, P1) in which two dithiocarbamate ligands are bonded to the nickel(II) ion in a S^S chelating mode forming a square planar geometry around the metal center. The photophysical properties of all the compounds have been investigated using UV-visible absorption, emission, and thermogravimetric analyses. Compounds exhibited intense blue photoluminescence with maximum emissions in the 330–336 nm region upon excitation in the UV region. A molecular docking study was performed to validate the potentials of these compounds in protein–ligand interactions against B-DNA Dodecamer (PDB Id: 1BNA) and cyclins (PDB Id: 1w98), which are indeed essential proteins of the cell cycle, and their proper functioning is necessary for the human health. [ABSTRACT FROM AUTHOR]

A series of two new Zn(II) complexes derived from 3-aminoquinoline are reported. The complexes were synthesized by the interaction of 3-aminoquinoline and Zn(II) ions in 2:1 molar ratio. The structure of synthesized complexes is investigated by elemental analyses, ESI-MS, FT-IR, 1H and 13C NMR and UV–Vis spectroscopic studies. A single crystal X-ray diffraction measurement study reveals tetrahedral geometry around the zinc ion, and existence as a neutral discrete molecule.

A series of stimuli-responsive AIEgens of tetraphenylethylene (TPE) fused imidazole derivatives (1–7) were synthesized, and their substituent controlled fluorescence properties in the solid state were explored. The structure of the synthesised compounds was characterized by NMR, mass and single crystal X-ray diffraction spectroscopy techniques. 1–7 exhibited a typical aggregation induced emissive (AIE) behaviour in the THF : water mixture. These compounds exhibited substituent dependent strong solid state fluorescence (Φf = 16.6–55.7%) with a tunable λmax between 458 and 496 nm. Chlorine substituted 6 showed the highest fluorescence efficiency (Φf = 55.7%), whereas acetyl substituted 3 exhibited the lowest fluorescence efficiency (Φf = 16.6%). All the seven compounds showed a mechanical pressure induced reversible fluorescence switching. Crushing 1–7 resulted in red shifted fluorescence, which was reversed to its initial state by heating/solvent vapour exposure. Interestingly, integration of 1–7 into a hydrophobic PMMA polymer resulted in blue shifted fluorescence at 470 nm, whereas that into hydrophilic PVA polymer resulted in red shifted fluorescence at 491 nm. Thus highly solid state emissive TPE fused imidazole compounds were prepared, and their stimuli-induced reversible fluorescence switching and polymer controlled tunable fluorescence were demonstrated. [ABSTRACT FROM AUTHOR]

An attempted incorporation of N-donor ligand in the coordination sphere of Ca in the molecular solid [Ca(H2O)4(4-nba)2] (4-nba=4-nitrobenzoate) resulted in the formation of the one-dimensional (1D) coordination polymers catena-[bis(μ-4-nitrobenzoato)-diaqua-calcium 4,4'-bipyridine] 1 and catena-[bis(μ-4-nitrobenzoato)-diaqua-calcium 1H-1,2,4-triazole] 2 with the N-heterocycle functioning as a solvate. The syntheses, crystal structures and properties of [Ca(H2O)2(4-nba)2]·L (L=4,4′-bipyridine 1; L=1H-1,2,4-triazole 2) are reported. The central Ca(II) in 1 and 2 exhibits eight-coordination and the aqua ligands are terminal, while 4-nitrobenzoate functions as a μ2-bridging ligand. The μ2-η2:η1 tridentate binding mode of the 4-nba ligand results in the formation of an infinite chain of edge-sharing {CaO8} polyhedra flanked by the 4-nitrobenzoates. The solvate 4,4′-bipyridine in 1 (or 1,2,4-triazole in 2) links adjacent polymeric chains with the aid of O-H···N hydrogen bonding interactions. A comparative study of {CaOx} polyhedral linking in structurally characterized calcium coordination polymers based on 4-nitrobenzoate is described. [ABSTRACT FROM AUTHOR]

Potassium salts of phenolate based polydentate xanthate ligands 4,4′-bis(2-dithiocarbonatobenzylideneamino)diphenyl ether (K2xan1) and 4,4′-bis(2-dithiocarbonatonaphthylmethylideneamino)diphenyl ether (K2xan2) have been synthesized and characterized, prior to use. The reaction of K2xan1 or K2xan2 with M(OAc)2 in Et3N affords access to a rare series of binuclear metallomacrocyclic xanthate complexes of the type [M2-μ2-bis-(κ2S,S-xan1/xan2)] (1–4) which quickly forms [2 : 2] binuclear N,O-bidentate Schiff base macrocyclic complexes of the type [M2-μ2-bis-(κ2N,O-L1/L2)] (L1 = 4,4′-bis(2-hydroxybenzylideneamino)diphenyl ether, L2 = 4,4′-bis(2-hydroxynaphthylmethylidene-amino)diphenyl ether) 5–8via evolution of CS2 in solution. The compounds were characterized by microanalysis, relevant spectroscopy (FT-IR, UV-visible), mass spectrometry (ESI-MS), and powder and single crystal XRD techniques. In vitro anticancer activity of all the compounds was evaluated against HEP 3B (hepatoma) and IMR 32 (neuroblastoma) by the MTT assay. Remarkably, the binuclear copper(ii) xanthate complexes were found to be extremely active against both the cell lines (IC50: 8.1 ± 0.8 μM (3), 8.8 ± 1.7 μM (4) against HEP 3B and 1.9 ± 0.3 μM (3) and 7.3 ± 0.6 μM (4) against IMR 32) and this projects them as good candidates for potent antitumor agents and the IC50 values confirm their better potency than the reference drug cisplatin. The flow-cytometric density plot illustrates the induction of apoptosis in HEP 3B and IMR 32 cells after treatment with K2xan1, 1, 3, 6 and 7. [ABSTRACT FROM AUTHOR]

The structural analysis of a cobalt(III) complex [Co(HL)2](OAc).H2O (1) [H2L = N-(2-hydroxyethyl)-3- methoxysalicylaldimine] reveals a tridentate chelation behaviour of the ligand H2L having a distorted octahedral coordination environment around the cobalt(III) center with a CoN2O4 chromophore. 1 behaves as an effective catalyst towards the oxidation of 3,5-di-tert-butylcatechol in different solvents, viz. dichloromethane (DCM), methanol (MeOH) and acetonitrile (MeCN) to its corresponding quinone derivative in aerial oxygen. The reaction follows Michaelis-Menten enzymatic reaction kinetics with turnover numbers (Kcat), 1.46 × 103, 1.21 × 103 and 2.16 × 103 h-1 in DCM, MeOH and MeCN, respectively. [ABSTRACT FROM AUTHOR]

N-Carbamylmaleamic acid ( malur) undergoes cyclodehydration under favourable conditions, as expected, to give N-carbamyl maleimide. N-(Carboxymethyl) maleamic acid ( malgly), however, does not undergo a similar cyclization reaction. Strong π bonding between the C and N of the amide group as well as two intramolecular hydrogen bonds makes malgly a planar molecule, as revealed by single-crystal X-ray studies. [ABSTRACT FROM AUTHOR]

Cu(II) complexes with Schiff bases DMIIMP, DMIIMBD, DMIIMBP, DMIIMCP, DMIIMMP, and DMIIMNP (see Introduction for definitions) are derived from condensation of 3,4-dimethyl 5-amino-isoxazole with salicylaldehyde and substituted salicylaldehydes. The newly synthesized ligands were characterized by IR, UV-Vis,1H NMR,13C NMR, mass spectra, and elemental analysis. The Cu(II) complexes were characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, thermogram, DTA, and single crystal analysis. The complexes have general formula [M(L)2]. The Schiff bases are bidentate coordinating through the azomethine nitrogen and phenolic oxygen of salicylaldehydes. Based on the analytical and spectral data, four-coordinate geometry is assigned for all the complexes. ESR and single crystal analysis suggests square planar geometry for all complexes. [Cu(DMIIMP)2] crystallizes in the orthorhombic system. Antimicrobial studies of Schiff bases and their metal complexes show significant activity with the metal complexes showing more activity than corresponding Schiff bases. Cytotoxicity of the copper complexes on human cervical carcinoma cells (HeLa) was measured using the Methyl Thiazole Tetrazolium assay. [ABSTRACT FROM AUTHOR]

Two new structurally isomeric, 2-(2,4,4-trimethyl-3,4-dihydro-2 H-benzo[ h]chromen-2-yl)-1-naphthol ( 1) and 3-(2,4,4-trimethyl-3,4-dihydro-2 H-benzo[ g]chromen-2-yl)-2-naphthol ( 3) have been synthesized from 2-acetyl-1-naphthol and ethyl-3-hydroxy-2-naphthoate, respectively, involving Grignard reaction, dehydration of the corresponding tertiary alcohols, and hetero Diels-Alder dimerization. The two benzochromenes ( 1 and 3) have been fully characterized by IR, NMR, and HRESIMS data. Their structures are further supported by crystallography of their corresponding acetates ( 2 and 4). J. Heterocyclic Chem., (2011). [ABSTRACT FROM AUTHOR]

Abstract: The neutral hexadentate Schiff base N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-yl-phenylidene)amino]ethyl}amino)ethyl]ethane-1,2-diamine (L) was used to synthesize new lanthanide(III) complexes of type [M(L)(NCS)3] (M=La, 1; Gd, 2; Tb, 3; Dy, 4). Single crystal X-ray diffractometry reveals the tricapped trigonal prismatic structure of all the compounds. Variable-temperature magnetic susceptibility measurements in 2–4 show the expected χ M T versus T plot for an isolated, mononuclear lanthanide(III) ion with 4f7, 4f8 and 4f9 configurations, respectively following Curie Law. [Copyright &y& Elsevier]

In the crystal structure of the title compound, C12H17N2 +·C7H5O4-, the cations and anions are linked by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, resulting in a homochiral left-handed molecular helical extended structure. The O—H⋯O and N—H⋯O hydrogen bonds are involved in the formation of the helical backbone. The seven-membered ring adopts a half-chair conformation. [ABSTRACT FROM AUTHOR]

Synthesis of novel 1,2,3-selena/thiadiazoles, linked to different benzo-1,3-heteroazole ring by sulfur has been reported. Structural features of the compounds have been analyzed by 1H and 13C NMR, mass and single crystal X-ray studies. [ABSTRACT FROM AUTHOR]

The title compound, [Sr(C7H4NO4)(H2O)7](C7H4NO4)·2H2O, was synthesized from the aqueous reaction of strontium carbonate with 4-nitrobenzoic acid. The structure consists of a nine-coordinate heptaaqua(4-nitrobenzoato-κ2 O, O′)strontium(II) complex cation, an uncoordinated 4-nitrobenzoate anion and two solvent water molecules. The cations, anions and solvent water molecules are linked with the aid of several O—H...O and C—H...O interactions, resulting in a three-dimensional hydrogen-bonding network. The hydrogen bonding between a solvent water molecule and a symmetry-related solvent water molecule results in the formation of a water dimer. [ABSTRACT FROM AUTHOR]

The title compound, (C8H12N)2[WS4], was synthesized by the aqueous reaction of ammonium tetrasulfidotungstate(VI) with benzyl(methyl)amine in a 1:2 molar ratio. The compound is isotypic with the corresponding Mo analogue, (C8H12N)2[MoS4], and its structure consists of a slightly distorted tetrahedral [WS4]2- dianion and two crystallographically independent benzyl(methyl)ammonium cations, with all atoms located in general positions. The cations and anion are linked by weak N—H⋯S and C—H⋯S interactions, the strength and number of which can explain the observed W-S bond distances. [ABSTRACT FROM AUTHOR]

Abstract: Copper(II) complexes having the general formula [Cu(L n )2] with the N,O-donor reduced Schiff bases N-(2-hydroxy-5-X-benzyl)-(R)-α-methylbenzylamine and N-(2-hydroxy-5-X-benzyl)-(S)-α-methylbenzylamine (X =Cl and Br) (HL n ) are described. These chiral complexes crystallize in the noncentrosymmetric P212121 (X =Cl) and P21 (X =Br) space groups. In each case, self-assembly via intermolecular C–H⋯O interaction leads to a supramolecular helical superstructure. [Copyright &y& Elsevier]

A dinuclear Fe(III) complex, [FeIII 2(L)2] (1) [H3L= N,N′-bis(3-methoxysalicylaldimine)-1,3-diaminopropan-2-ol], has been synthesized and characterized using microanalysis, spectroscopy and X-ray crystallography. Structural analysis reveals a pentadentate chelation behaviour of the trianionic ligand H3L, having a distorted octahedral coordination environment around each iron(III) center with an FeN2O4 chromophore. Variable-temperature magnetic susceptibility measurements of 1 indicate an antiferromagnetic interaction between the two iron(III) centers, coupled with J =−28.5. 1 behaves as an effective catalyst towards the oxidation of 3,5-di-tert-butylcatechol in different solvents, viz. methanol, dichloromethane and acetonitrile, to its corresponding quinone derivative in aerial oxygen. The reaction follows Michaelis-Menten enzymatic reaction kinetics with turnover numbers (K cat) 7.51×102, 1.69×103 and 1.23×103 h− 1 in methanol, dichloromethane and acetonitrile, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Metal–organic frameworks with the compositions [Zn(bpy)(bdc)(H2O)] n 1, [Zn(bpy)(btec)1/2(H2O)] n 2, [Cd(bpy)(bdc)(H2O)] n 3 and Cd(bpy)(btec)1/2(H2O)] n 4 (H2bdc=1,4-benzenedicarboxylic acid=terephthalic acid, H4btec=1,2,4,5-benzenetetracarboxylic acid and bpy=2,2′-bipyridine) have been synthesized and characterized using spectroscopic and single-crystal X-ray diffraction techniques. In these complexes, ZnII/CdII-2,2′-bipyridine units and carboxylate anions exists as nodes and spacers respectively. An infinite 1D zig-zag chain structure is observed for both complexes 1 and 3, whereas complexes 2 and 4 display a 3D supramolecular architecture. The complexes are found to be photoluminescent, porous and show significant thermal stability. [Copyright &y& Elsevier]

Abstract: The reaction of the monomeric compound [Ca(H2O)4(η1-4-nba)(η2-4-nba)] 1 (4-nba=4-nitrobenzoate) with N-methylimidazole (N-MeIm) or imidazole (Im) at 100 oC results in the formation of the anhydrous mixed ligand complexes of composition [Ca(L)(4-nba)2] (L= N-MeIm 2; L=Im 3). The compounds were characterized by elemental analysis, IR, UV–Vis and 1H NMR spectra, TG-DSC thermograms, weight loss studies and the structure of 2 was determined by single crystal X-ray crystallography. Compounds 2 and 3 can be transformed into 1 by heating with water. At elevated temperatures all compounds (1–3) are thermally decomposed to CaO. Compound 2 crystallizes in the centrosymmetric triclinic space group with all atoms located in general positions. The structure reveals that 2 is a polymer and can be formulated as catena-poly[[(N-methylimidazole)calcium(II)](μ2-η1:η1-4-nitrobenzoato)(μ3-η2:η1-4-nitrobenzoato)]. The structure of [[Ca(N-MeIm)](μ2-η1:η1-4-nba)(μ3-η2:η1-4-nba)] n 2 consists of a central Ca(II) ion, a terminal N-MeIm ligand and two crystallographically independent 4-nba ligands. In the crystal structure, each Ca(II) is bonded to a nitrogen atom of N-MeIm and five oxygen atoms from five symmetry related 4-nba ligands resulting in a distorted {CaO5N} octahedron. One of the unique 4-nitrobenzoate in each formula unit functions as a bridging bidentate ligand (μ2-η1:η1-4-nba) and is linked to two symmetry related Ca(II) ions leading to the formation of an infinite chain extending along a axis with a long Ca⋯Ca separation of 5.531(1)Å. The second independent 4-nba ligand (μ3-η2:η1-4-nba) is coordinated to three different Ca(II) ions with both the carboxylate oxygen atoms linked to the same infinite chain formed earlier and one of the carboxylate oxygen atoms functions as a monoatomic bridge between two symmetry related Ca(II) ions. This bridge links two chains with a shorter Ca⋯Ca separation of 3.8585(7)Å resulting in the formation of a one-dimensional ladder structure. The oxygen atoms of the nitro groups are involved in C–H⋯O interactions. A comparative study of 30 Ca(II) coordination polymers is described. [Copyright &y& Elsevier]

The title compound, C10H18O7S2, was synthesized by reacting diethylene glycol with allyl chlorosulfonate in the presence of pyridine. The asymmetric unit consists of half a molecule, which is located on a twofold rotation axis. In the crystal structure, the molecules are involved in several weak C—H...O interactions. [ABSTRACT FROM AUTHOR]

Potassium salts of phenolate based polydentate xanthate ligands 4,4'-bis(2-dithiocarbonatobenzylideneamino)diphenyl ether () and 4,4'-bis(2-dithiocarbonatonaphthylmethylideneamino)diphenyl ether () have been synthesized and characterized, prior to use. The reaction of or with M(OAc)2 in Et3N affords access to a rare series of binuclear metallomacrocyclic xanthate complexes of the type [M2-μ(2)-bis-(κ(2)S,S-xan(1)/xan(2))] () which quickly forms [2 : 2] binuclear N,O-bidentate Schiff base macrocyclic complexes of the type [M2-μ(2)-bis-(κ(2)N,O-L(1)/L(2))] ( = 4,4'-bis(2-hydroxybenzylideneamino)diphenyl ether, = 4,4'-bis(2-hydroxynaphthylmethylidene-amino)diphenyl ether) via evolution of CS2 in solution. The compounds were characterized by microanalysis, relevant spectroscopy (FT-IR, UV-visible), mass spectrometry (ESI-MS), and powder and single crystal XRD techniques. In vitro anticancer activity of all the compounds was evaluated against HEP 3B (hepatoma) and IMR 32 (neuroblastoma) by the MTT assay. Remarkably, the binuclear copper(ii) xanthate complexes were found to be extremely active against both the cell lines (IC50: 8.1 ± 0.8 μM (), 8.8 ± 1.7 μM () against HEP 3B and 1.9 ± 0.3 μM () and 7.3 ± 0.6 μM () against IMR 32) and this projects them as good candidates for potent antitumor agents and the IC50 values confirm their better potency than the reference drug cisplatin. The flow-cytometric density plot illustrates the induction of apoptosis in HEP 3B and IMR 32 cells after treatment with , , , and .

A flip-flop extended water structure assists the formation of sulfate anion helices (both left- and right-handed) in a crystalline hydrate of a simple organic-inorganic compound [C6H10N2]SO4. 1.5H2O (1).