Photochromism and decolorization controlled by auxiliary ligands of complexes derived from 1‐methyl‐4,4′‐bipyridinium cation

Abstract

Three 1-methyl-4,4′-bipyridinium (MQ + )-based complexes, {[Cd(MQ)(p-BDC) Br]⋅H 2 O} n (1), {[Cd(MQ)(m-BDC)(H 2 O)Br]⋅3H 2 O} n (2) and Cu(MQ)Br 2 (3) (p-H 2 BDC = 1,4-benzenedicarboxylic acid, m-H 2 BDC = 1,3-benzenedicarboxylic acid), have been synthesized and structurally characterized. Compounds 1 and 2 are one-dimensional coordination polymers constituted of one coordinated MQ + cation, one coordinated Br − ion and chains of Cd 2+ ions connected by deprotonated BDC 2− units, which both have photochromism but different decolorization behaviors. The structures and photoresponsive behaviors controlled by auxiliary ligands have been explored. Compound 3 is constituted of one Cu + center, one MQ + ligand and two coordinated Br − ions in a 'V' configuration, exhibiting no photochromism.