Structure and photochromic properties of two cadmium coordination polymers derived from viologen ligands

Abstract Two novel 1D Cd‐based coordination polymers (CPs) {[Cd(MQ)(HBTC)(H2O)2] ⋅ (H2BTC) ⋅ 4H2O}n (1) and {[Cd(AQ)(HBTC)(H2O)Br] ⋅ 2H2O}n (2) have been prepared in the reaction of Cd2+ with different viologen ligands such as 1‐methyl‐4,4′‐bipyridinium bromide (MQBr) or 1‐amyl‐4,4′‐bipyridinium bromide (AQBr) in the presence of 1,3,5‐benzenetricarboxylic acid (H3BTC). The Cd2+ ions are bridged by HBTC2− anions to take shape a 1D configuration for two CPs. Additionally, 1 and 2 both show photochromism due to the photoinduced electron transfer (ET) from electron‐rich O atoms to electron‐deficient viologen moieties. Compared with 2, compound 1 has a rapid photoresponsive rate. The different photochromic behaviors have been discussed adequately.