An Electron-Deficient Coordination Polymer Based on a Viologen Ligand Accompanying Photochromism, Vaporchromism, and Photoswitchable Luminescence Properties

A novel viologen ligand, 1,1'-bis-(4-carboxybenzyl)-4,4'-bipyridinium- dibromide (H2BpybcBr2), has been synthesized and successfully introduced into cadmium based coordination polymers (CPs) when it reacts with cadmium perchlorate and 5-phenyltetrazole (5-Ph-Ptz) at room temperature. CPs has been characterized with single-crystal X-ray diffraction, powder X-ray diffraction, and thermogravimetric analysis. CP 1 shows high sensitivity to ultraviolet-visible radiation and exhibits the electron-transfer (ET) photochromic properties. Interestingly, CP 1 exhibits photocontrolled luminescence properties during the coloration-decoloration process and can be used to detect ammonia and aniline in solid state.