A novel photochromic complex based on a viologen ligand with rapid inkless and erasable printing, anti-counterfeiting and amine-selective responses

In this work, we have synthesized a novel complex {[Zn2(Bpybc)0.5(L)·H2O]·DMA·H2O}n (1) (H2BpybcCl2 = 1,1′-bis(4-carboxybenzyl)-4,4′-bipyridinium dichloride, H4L = 1,2,4,5-benzenetetracarboxylic acid) by solvothermal method. 1 has a 3D network stacking structure. 1 exhibits rapid and reversible photochromic behavior, showing the color change visible to the naked eye after being irradiated. 1 has been characterized by infrared spectroscopy, powder X-ray diffraction analysis, UV–vis absorption spectroscopy and electron paramagnetic resonance spectroscopy. The relationship between the structure of 1 and photochromic behavior has been discussed. 1 can be used as an anti-counterfeiting material and amine-selective response material at a fast speed. 1 can also be deposited on filter paper and used as an inkless and erasable printing medium. In addition, 1 has photomodulated fluorescence properties.