Browsing by Author "Sawant, Pradnya S."

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    Interaction of metal ions with Schiff bases having N2O2 donor sites: Perspectives on synthesis, structural features, and applications
    (Elsevier, 2023) Vernekar, Beena K.; Sawant, Pradnya S.
    Metal Schiff base complexes are versatile platforms for the development of potential catalysts, potent biomaterials, or luminescent compounds. Transition metals possess a diverse array of properties that can be manipulated to yield promising candidates for the future in various industrial applications. Metal Schiff base complexes represent a class of compounds that have become a field of immense interest because of their intriguing chemical and physical properties and their wide range of applications in several scientific fields. The reaction of transition metal elements with a polydentate Schiff base ligand to form metal complexes offers a good platform for combining the chemical, electronic, magnetic, optical, and redox properties of metal complexes with those of the organic materials, generating new functional materials with useful mechanical, catalytic, thermal and chemical, optoelectronic, structural and magnetic properties. The transition metal complexes can often mimic biological sites; they are, therefore, of great interest as enzyme models. This review discusses the structural features of metal complexes of the first series of transition metals with Schiff bases as ligands having N2O2 coordination sites. Further perspectives concerning the synthesis, structural aspects, characterization, and applications are presented.
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    New diclofenac salts with the dense hydrogen bond donor propane-1,3-diaminium
    (Royal Society of Chemistry, 2024) Breckell, Jaxon R.; Conte, Luke; Potts, Michael W.; Sawant, Pradnya S.; Butcher, Raymond J.; Vernekar, Beena K.; Richardson, Christopher
    A series of solvatomorphic structures of the anti-inflammatory drug diclofenac (dcfn−) and the dense hydrogen bond donor propane-1,3-diaminium (H2pn2+) are reported. Single crystal X-ray diffraction shows each structure contains a dcfn2·H2pn formula unit (1) with solvent of crystallisation [1·2H2O, 1·3H2O, 1·2MeOH, 1·EtOH·2H2O, 1·iPrOH, 1·2DMSO]. The propane-1,3-diaminium molecules evoke extensive networks of hydrogen-bonded interactions with the solvates and the dcfn carboxylate groups. All structures are lamellar with hydrophilic solvate-containing sheets separating hydrophobic layers of aromatic dcfn moieties. Supporting characterisations by powder X-ray diffraction, Fourier transform infrared and 1H NMR spectroscopies, thermal analysis (TG–DSC) and elemental microanalysis were used to reveal the sometimes delicate phase distributions amongst this set of compounds. TG–DSC showed a consistent pattern across the water and alcohol-containing compounds with desolvation occurring before melting to an anhydrous ionic liquid form around 140–150 °C. Heating to approximately 200 °C induces a minor dehydration reaction that covalently links diclofenac and propan-1,3-diaminium molecules via amide bond formation. A mechanochemical synthetic route to 1·3H2O was determined and this compound was selected for study by gravimetric water vapour adsorption. These studies showed the lamellar structure of 1·3H2O displays reversible but imperfect water adsorption between 0% and 50% relative humidity, which is ascribed to some crystal fatigue. This work expands crystal engineering strategies for new and existing active pharmaceutical ingredients to low molecular weight diamines.