A Novel Multichromic Cd(II) Coordination Polymer Based on a Viologen Ligand Exhibiting Multichroism, Aniline Detection and Luminescence Properties

As a powerful strategy to precisely fabricate multifunctional materials with unique optoelectronic properties, donor-acceptor (D–A) alignment, which integrates D–A pairs into the modular and versatile crystalline cation metal–organic frameworks (CMOFs) and cation coordination polymers (CCPs) is applied at the molecular level. In this paper, a photo- and thermochromic CCP, named [Cd (PTA)_0.5(bcbpy)_0.5Br] (1), was successfully produced by the self-assembly of a photo- and thermoactive 1,1'-bis((3-carboxylatobenzyl)-4,4'-bipyridinium)-dibromo ligand (H₂bcbpy·2Br) with cadmium chloride and terephthalic acid (PTA). This complex is characterized by single-crystal X-ray diffraction, powder X-ray diffraction and it exhibits high sensitivity to both heat and different illuminant. The exceptional difunctional characteristics of electron-transfer (ET) thermochromism and photochromism in 1 are mostly influenced by the photosensitivity and thermal sensitivity of H₂bcbpy·2Br. Otherwise, during the coloration-decoloration phase, there is a photoluminescence “on/off switch” which would direct the synthesis of new crystals.