• BIKSHANDARKOIL R SRINIVASAN

      Articles written in Journal of Chemical Sciences

    • Syntheses, structure and properties of Alkaline-earth metal salts of 4-Nitrophenylacetic acid

      BIKSHANDARKOIL R SRINIVASAN KIRAN T DHAVSKAR CHRISTIAN NÄTHER

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      The synthesis, crystal structure, spectral characteristics and thermal properties of alkaline-earth metal salts of 4-nitrophenylacetic acid (4-npaH) namely, [Mg(H₂O)₆](4-npa)₂·4H₂O (4-npa = 4-nitrophenylacetate) (1), [Ca(H₂O)₂(4-npa)₂] (2) and [Sr(H₂O)₃(4-npa)₂]·4.5H₂O(3) are reported. In 1, the 4-npa ion functions as a charge balancing counter anion for the octahedral [Mg(H₂O)6]²⁺ unit with the Mg(II) ion situated on a centre of inversion. The two unique lattice water molecules link the [Mg(H₂O)₆]²⁺ cations and 4-npa anions with the aid of O-H· · ·O interactions. Compounds 2 and 3 are one-dimensional (1-D) coordination polymers containing an eight coordinated Ca(II) situated in a general position and a nine coordinated Sr(II) located on a twofold axis. The μ₂-bridging tridentate binding modes of the crystallographically independent 4-npa ligands in 2 and the unique 4-npa ligand in 3 link the bivalent metal ions into an infinite chain with alternating Ca· · · Ca separations of 3.989 and 4.009 Å, respectively, and a single Sr· · · Sr separation of 4.194Å in the 1-D chain.

    • Comments on ‘‘Carbonyl releasing Schiff base complex of Fe (III): synthesis, physicochemical characterization, antimicrobial and anticancer studies’’

      BIKSHANDARKOIL R SRINIVASAN

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      The authors of the title paper (J. Chem. Sci. (2020) 132 44) claim to have synthesized and characterized a carbonyl releasing Schiff base complex of Fe(III) to study its antimicrobial and anticancer properties. A critical analysis of the reported claims reveals that the so-called carbonyl releasing Schiff base complex formulated as containing two carbonyl (CO) ligands bonded to a pentavalent iron, is a dubious material. In this letter to the Editor, it is proved that the title paper is completely erroneous.

      A so-called carbonyl releasing Schiff base complex formulated as containing two CO ligands bonded to a pentavalent iron, is a dubious material.

    • Synthesis, structural, and DFT studies of mixed ligand copper(II) malonates

      MEGHA S DESHPANDE SUDESH M MORAJKAR MINI BHARATI AHIRWAR MILIND M DESHMUKH BIKSHANDARKOIL R SRINIVASAN

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      The synthesis, spectra, electrochemical studies, single crystal structures and DFT studies of twonew mixed ligand copper(II) malonates viz. [Cu(H2O)(bpy(OH)2)(mal)].H2O 1 and [Cu(H2O)(dmp)(mal)].2H2O 2 (bpy(OH)2) = 2,2Ꞌ-bipyridine-6,6Ꞌ-diol; dmp = 6,6Ꞌ-dimethyl-1,10-phenanthroline; H2mal =malonic acid) are reported. The malonate, bpy(OH)2 (in 1), dmp (in 2) function as bidentate ligands in thedistorted square pyramidal Cu(II) compounds while the aqua ligand occupies the axial site in 1. In contrast, oneNof dmp occupies the axial site in 2. ESR studies reveal the distorted coordination geometry of Cu(II) in 1 and 2.Extensive hydrogen bonding (O-H···O and C-H···O) is observed between the malonate oxygens, oxygens ofwater and the monomeric Cu(II) species resulting in the formation of hydrogen bonded network structure in 1 and2. The neutral monomeric Cu(II) species and lattice water molecules in 2 are linked viaO-H···Ohydrogen bondforming a water dimer. Both compounds exhibit π···π stacking and carbonyl(lp)···π interactions (in 2) stabilizethe structure. DFT studies reveal stronger hydrogen bond energy for 2 compared to 1, while π···π stacking energyis larger in 1 than in 2 and carbonyl(lp)···π interactions in 2 are found to be moderate. In a series of fivecoordinated mixed ligand Cu(II) malonates, compound 2 exhibits maximum deviation of the {CuN2O3}polyhedron from square pyramidal towards trigonal bipyramidal geometry.

      The supramolecular network structures of [Cu(H2O)(bpy(OH)2)(mal)]·H2O 1 and [Cu(H2O)(dmp)(mal)]·2H2O 2 are directed by O–H⋅⋅⋅O and C–H⋅⋅⋅O interactions. Additionally π⋅⋅⋅π stacking in 1 and π⋅⋅⋅π /carbonyl(lp)⋅⋅⋅π interactions in 2 contribute to the structure stabilization. 2 is an unique example showing severe distortion of the {CuN2O3} polyhedron.

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