University of Calcutta, Kolkata
Ashutosh Ghosh received PhD from IACS in 1987. His research work focuses on the synthesis, structural characterisation, magnetic properties, and catalytic activities of homo-and heterometallic polynuclear complexes of 1st transition metal ions. He has served as a UNESCO Fellow at Charles University, Czechoslovakia, a MONBUSHO Fellow at Nagoya University, Japan, a JSPS Fellow at Tsukuba University, Japan and also as a Visiting Sci-entist at the University of Utah, USA, and the University of Dusseldorf, Germany. He has been conferred with the Rheometric Scientific-ITAS Award in 1995 and the CRSI Bronze Medal in 2016. He is a Fellow of the West Bengal Academy of Science and Technology (2013) and of the Indian Academy of Sciences (2017).
Session 3A: Inaugural Lectures by Associates/Fellow
Chairperson: S Sivasanker, Indian Institute of Technology, Chennai
Hetero-metallic complexes derived from N2O2 donor ligands: Molecular shapes, supramolecular structures, catalysis and magnetism
The symmetrical and unsymmetrical N2O2 donor salen type di-Schiff base complexes of Cu(II) and Ni(II) can conveniently be used as ‘metalloligands’ as the oxygen atoms of the chelated Schiff base often coordinate to a second metal ion. Using the metalloligands, [CuL] or [NiL], several heterometallic complexes incorporating various metal ions along with some anionic coligands have been synthesised. The complexes are obtained in different shapes, which have been determined mostly by the coordination modes of the anionic coligands. Some fundamental solid state phenomena like ‘isomerism’ (linear-bent, coordination position and supramolecular isomerism) ‘polymorphism’, ‘cocrytallization’ are ob-served in such trinuclear complexes due to the flexibility in the coordination mode of, both, the metal and anionic co-ligands. Most heterometallic compounds satisfy non-zero spin ground state hence show ferrimagnetic exchange interactions. The coupling usually occurs through diphenoxido bridge between the metal centres. However, the anionic coligand can also take part in bridging to modulate the bridging angles and hence the coupling constant. Moreover, some of these compounds, consisting of CuII2DyIII, Cu2TbIII etc. are found to behave like Single Molecule Magnets, and the shapes of the molecule are found to have a considerable effect on the SMM behaviours. The catalytic oxidase activities, e.g., catechol-oxidase- and phenoxazinone-synthase- like activities of some of these heterometallic complexes are found to be very high presumably due to heterometallic cooperative effect.