A novel multicolor viologen-derived Zn-organic coordination polymer for environment friendly ink free erasable printing

Abstract A novel multifunctional coordination polymer {[Zn(HCOO) (bcbpy)Cl]·H2O}n (1) with multiple colour-changing has been synthesized from Zn(NO3)2·6H2O, and viologen ligand 1,1′-bis-((3-carboxylatobenzyl)-4,4′-bipyridinium) dichloride (H2bcbpy·2Cl). In coordination polymer (CP) 1, bcbpy ligands bridge Zn2+ cations to form a 1D wave-like chain. CP 1 exhibited photochromic properties under xenon lamp and blue light irradiation while obtaining a structurally stable light product 1T. CP 1 thermochromic properties can also be observed during heating. 1 showed photo-controlled fluorescence properties during color rendering and decolorization, and its properties were studied. Interestingly, CP 1 can be deposited in filter paper by coating it with a solution of H2O. The filter paper can be used as a printing medium without ink.