Chromism of three coordination polymers based on 1 (2 carboxyethyl) 4,4' bipyridinium ligand
Abstract Three novel coordination polymers (CPs) based on 1 (2 carboxyethyl) 4,4' bipyridinium bromide (HCBbpyBr) have been prepared [Cd2(CBbpy)(m BDC)2(H2O)4]*H2O}n (1) [Ni(CBbpy)2(H2O)2](p BDC)*6H2O}n (2) [Co(CBbpy)2(H2O)2](p HBDC)2*3H2O}n (3) (m H2BDC 1,3 benzenedicarboxylic acid; p H2BDC 1,4 benzenedicarboxylic acid) The crystal structures and chromic behaviors of three compounds have been studied. Single crystal X ray analyses reveal that compound 1 features a 2D layered structure, compounds 2 and 3 have similar 1D double chain like structure. Compound 1 displays electron transfer (ET) photochromism, compound 2 exhibits ligand based ET photochromism and metal based hydrochromism owing to ligand field change induced by de /rehydration, while compound 3 exhibits ET thermochromism accompanying ligand field change around the metal. The differences in the central metal ions and auxiliary carboxylate units have a great influence on the final structures, and further result in their different chromic behaviors.