• Rajesh Chakrabarty

      Articles written in Journal of Chemical Sciences

    • Structural, thermal and spectroscopic properties of supramolecular coordination solids

      Birinchi Kumar Das Sanchay Jyoti Bora Monideepa Chakrabortty Laksheswar Kalita Rajesh Chakrabarty Ramakanta Barman

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      Molecules in metal isonicotinate tetrahydrates, M(NC5H4-p-CO2)2.4H2O with M = Mn, Fe, Co, Ni, Cu, Zn, consisting of the hexacoordinate complexestrans-[M(NC5H4-p-CO2)(OH2)4], participate in exhaustive hydrogen-bond formation among themselves to lead to a robust 3D supramolecular network in the solid state. Solid-state diffuse reflectance UV-Vis-NIR spectra of the complexes have been assigned to ligand field and charge transfer transitions. Sharp weight loss due to dehydration, as shown by TGA of Cu(NC5H4-p-CO2)2.4H2O, suggests the suitability of this complex for the gravimetric estimation of copper.

    • Cobalt(III)-oxo cubane clusters as catalysts for oxidation of organic substrates

      Birinchi Kumar Das Rajesh Chakrabarty

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      Transition metal coordination complexes play a vital role as catalysts in the oxidation of organic substrates including renewable chemicals in an economically viable and environmentally friendly way. Here we highlight the preparation, characterization and application of oxo-cubane complexes of cobalt(III) as oxidation catalysts using air and water as oxidants. Cobalt(III)-oxo complexes of the type Co4O4(O2CR)4L4 have been prepared by a general method and these have been characterized by analytical, spectroscopic, electrochemical and crystallographic methods. These soluble complexes have shown promising utility as catalysts in the aerobic oxidation of side chains of alkylaromatic hydrocarbon compounds. Oxidation of neat ethylbenzene has shown very high conversion and selectivity for acetophenone formation. On the other hand, oxidation of 𝑝-xylene has been found to yield both 𝑝-toluic acid and terephthalic acid. It is also possible to oxidize 𝑝-xylene in an aqueous medium under moderate applied O2 pressure. Selective epoxidation of 𝛼-pinene with air as the oxidant also takes place with the cobalt(III)-based homogeneous catalysts.

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