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Articles written in Journal of Chemical Sciences

• Simple inorganic complexes but intricate hydrogen bonding networks: Synthesis and crystal structures of [MII(opda)2(NO3)2] (M = Zn and Cd; opda = orthophenylenediamine)

The compounds [ZnII{C6H4(NH2)2}2(NO3)2], (1) and [CdII{C6H4(NH2)2}2(NO3)2] (2) have been prepared (C6H4(NH2)2 = orthophenylenediammine = opda) and characterized by routine spectroscopic methods and single crystal X-ray diffraction analysis. Compound 1 crystallizes in orthorhombic space group $Pcab$, where as compound 2 crystallizes in monoclinic space $P2_1/n$. In the crystal structure of 1 an extended hydrogen bonding network is formed involving zinc coordinated amines and nitrato ligands. The compound 2 consists of molecules in which the cadmium ion is eight coordinated, with two bidentate nitrate groups and two bidentate opda ligands. The geometry around the cadmium described as a distorted dodecahedron. The crystal structure of 2 shows an intricate hydrogen bonding network, formed by amine and nitro groups coordinated to cadmium.

• A simple coordination complex exhibiting colour change on slight structural modification: Synthesis and crystal structures of violet and yellow forms of [NiII(opda)2(NCS)2] (opda = orthophenylenediamine)

The violet-coloured compound [NiII(opda)2(NCS)2] (1) undergoes colour change to strawyellow colour retaining its molecular composition on standing over long period of time at room temperature in the solid state. Compound 1 (violet form) and its yellow-form [NiII(opda)2(NCS)2] (2) (opda = orthophenylenediammine) have been characterized by routine spectroscopic methods and single crystal X-ray diffraction analysis. Compound 1 crystallizes in monoclinic space group $P2_1/c$ and its yellow form (compound 2) retains same space group. Their crystal structures show an intricate supramolecular network based on N-H$\cdots$S hydrogen bonds, that involve amine and thiocyanate groups coordinated to nickel(II).

• Syntheses and solid state structures of zinc (II) complexes with Bi-dentate 𝑁-(Aryl)imino-acenapthenone (Ar-BIAO) ligands

We have synthesized five zinc complexes of molecular formulae [ZnCl2(2,6-dimethylphenyl-BIAO)]2 (1a), [ZnBr2(2,6-dimethylphenyl-BIAO)]2 (1b), [ZnI2(2,6-dimethylphenyl-BIAO)]2(1c), [ZnBr2(mes-BIAO)]2(2b) and [ZnBr2(dipp-BIAO)] (3b) with rigid unsymmetrical iminoacenaphthenone ligands, (2,6-dimethylphenyl-BIAO) (1), (mesityl-BIAO) (2) and (2,6-diisopropylphenyl-BIAO) (3). The zinc complex 1a was prepared by the reaction of ZnCl2 and neutral (mesityl-BIAO) (1). However, complexes 1b, 2b and 3b were obtained by the treatment of ZnBr2 and neutral ligands 1-3 respectively in 1:1 molar ratio in dichloromethane at ambient temperature. In a similar reaction of ZnI2 with (2,6-dimethylphenyl-BIAO) (1) in dichloromethane the corresponding iodo-complex 1c was obtained in good yield. All the zinc (II) complexes are characterized by FT-IR, 1H and 13C{1H} NMR spectroscopic techniques. The solid state structures of the complexes 1a, 1b, 1c, 2b and 3b are confirmed by single crystal X-ray diffraction analysis. The molecular structures of complexes 1a, 1b, 1c and 2b reveal the dimeric nature of the complexes and subsequently the centre atom zinc is penta-coordinated to adopt distorted trigonal bipyramidal geometry around it. In contrast, the complex 3b is in monomeric in nature due to bulkier size of the ligand and zinc ion is tetra coordinated to adopt distorted tetrahedral geometry.

• Synthesis and characterization of mononuclear copper(II) complexes of pyridine 2-carboxamide: Their application as catalyst in peroxidative oxidation and antimicrobial agents

Four water soluble copper(II) complexes, [Cu(HL)2 (H2O)2]Cl2 (1), [Cu(HL) 2 (ClO4)2 ] (2), [Cu(HL)2 (SCN)2] (3) and [CuL 2 ]·8H 2 O (4), where HL is pyridine 2–carboxamide, have been synthesized and characterized by various spectroscopic techniques. Structures have been determined by single crystal X-ray crystallography. The pH induced inter-conversion of Cu(HL)2 (H2O)2 ]Cl2 (1) and [CuL2]·8H2O (4) through co-ordination mode switching was investigated thoroughly with the help of absorption spectroscopy. Complexes 1–3 were found to be active catalysts for the oxidation of toluene, ethyl benzene and cyclohexane in the presence of hydrogen peroxide as the oxidant under mild conditions. Toluene was oxidized to benzyl alcohol and benzaldehyde, ethyl benzene was oxidized to 1-phenylethanol and acetophenone and cyclohexane was oxidized to yield cyclohexanol and cyclohexanone Antimicrobial activities have been investigated with these copper(II) complexes against gram + ve bacteria, gram − ve bacterial and fungal species.

• Synthesis of multilayer polymer-immobilised nanosilver for catalytic study in condensation reaction of aniline and acetylacetone

Silver nanoparticles were synthesized in green route with non-hazardous polyvinyl alcohol and polyvinylpyrrolidone as stabilizing as well as reducing agents and water as green solvent. This silver nanoparticle-embedded polymer composite film, Ag/PVA–PVP was characterized by UV–Vis spectroscopy,SEM and TEM. The catalytic activity of this film was evaluated in reduction of p-nitrophenol, acylation of aniline and synthesis of a b-enaminone, 4-phenylamino-pent-3-en-one with appreciably good results. benaminonesynthesis reaction was chosen to study the effects of kinetic parameters such as reactant quantity, catalyst loading, solvents and temperatures. In a typical reaction, 89% conversion was achieved. A probable chemical reaction mechanism is suggested. Kinetic model fitting for the synthesis of b-enaminone reaction was done for the first time here. Heterogeneous kinetic model following Eley-Rideal pathway showed an excellent data fitting for the reaction. The rate law parameters were estimated.

• # Journal of Chemical Sciences

Volume 132, 2020
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• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019