Two isomeric Cd-viologen coordination polymers with photochromic and photoluminescence properties

Two novel isomeric Cd-viologen coordination polymers [Cd(CV)(0)(.5)center dot(p-BDC)center dot H2O] (1) and [Cd(CV)(0)(.5).(m-BDC)center dot H2O] (2) (CV= N,N'-4,4'-bipyridiniodipropionate, p-BDC2- = terephthalate, m-BDC2- = isophthalate) have been successfully assembled and well characterized. Compounds 1 and 2 have the same empirical formula but different structures. Isomer 1 exhibits a 3D structure, while compound 2 exhibits a 1D channel structure. Interestingly, the photochromic behaviors of the two compounds were different due to different electron transfer pathways, with compound 1 reaching light saturation at 80 min and compound 2 reaching light saturation at 35 min. Furthermore, we also studied the photofluorescence of two isomers to enrich the crystal properties.