Investigation of structure-property correlation in 2,2′-dipyridyl diselenide based derivatives

Abstract

Structure-property correlation in 2,2′-dipyridyl diselenide derivatives has been investigated using four test cases 2,2′-dipyridyl diselenide <strong>(1)</strong>, 2,2′-disleno-bis(3-pyridinol) <strong>(2)</strong>, 2,2′-diseleno-bis(3-carboxypyridine) <strong>(3)</strong> and 2,2′-diseleno-bis (3-nicotinamide) <strong>(4)</strong>. Nature of substituent at C-3 position of pyridyl ring has been found to be a key factor in controlling the molecular structure, its packing capacity and thermal stability of molecular assembly. Strong electron withdrawing group (viz., -COOH, -CONH₂) reduces the charge on selenium and enforces <em>sp²</em> hybridization induced planar molecular configuration. Bent molecules <strong>1 </strong>and<strong> 2</strong> favor denser crystallographic packing in comparison to planar molecule <strong>3 </strong>and<strong> 4</strong>. Thermal investigation reveal that temperature range for thermal decomposition to elemental selenium for <strong>4</strong> and <strong>2</strong> is 210–460 °C and 150–275 °C respectively indicating higher thermal stability of former. The higher thermal stability of <strong>4</strong> has been attributed to secondary intermolecular interactions with the entrapped solvent molecule in the molecular lattice, which is not the case for <strong>2</strong>. The evaluation of these compounds for glutathione peroxidase (GPx) like activity revealed that a stronger electron withdrawing group at C-3 position presented better activity. Thus C-3 position of pyridyl ring of dipyridyl diselenide derivatives can be adopted as one of the focus points for future drug designing processes.