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

Structure-property correlation in 2,2'-dipyridyl diselenide derivatives has been investigated using four test cases 2,2'-dipyridyl diselenide (1), 2,2'-disleno-bis(3-pyridinol) (2), 2,2'-diseleno-bis(3-carboxypyridine) (3) and 2,2'-diseleno-bis (3-nicotinamide) (4). 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 sp(2) hybridization induced planar molecular configuration. Bent molecules 1 and 2 favor denser crystallographic packing in comparison to planar molecule 3 and 4. Thermal investigation reveal that temperature range for thermal decomposition to elemental selenium for 4 and 2 is 210-460 degrees C and 150-275 degrees C respectively indicating higher thermal stability of former. The higher thermal stability of 4 has been attributed to secondary intermolecular interactions with the entrapped solvent molecule in the molecular lattice, which is not the case for 2. 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.