An ultra-photosensitive viologen-based hybrid crystalline material with unconventional transfer pathways

Abstract

Viologen units are widely used in UV/X-ray detection, photoelectric detection, intelligent anti-counterfeiting, and inkless printing owing to their excellent photo-induced electron transfer (PET). In the previous research, the traditional electron transfer channel types of highly photosensitive viologen-based PET materials were mostly O/X … N (X=Cl, Br, I). In this work, we synthesized a photochromic 0-dimensional supramolecular, [Cd1.5(m-CBbpy)(Cl)4(DMA)]n (1). The electron transfer type of 1 is unconventional Cl⋯H–C, which has an ultra-sensitive response to UV and indoor light. (after 0.3 s under 135.2 mW cm−2 Xe lamp, UV absorption can reach 1/3 of the light saturation; after 20 min under indoor light, the color of 1 turned blue). This is because by introducing more Cl− as electron donors, the cyano group (–CN) on the m-CBbpy·Cl ligand enhances the electron acceptance ability, and the charge interaction formed by Cl− and m-CBbpy+ assists electron transfer (ET). In addition, 1 has amine chemochromism, electrochromism, and wide photocurrent response from 375 to 1850 nm. Therefore, 1 is an excellent material for light/amine/electrical stimulation response and a candidate material for photoelectric detection in the UV–Vis-SWIR region. And it provided clues for developing highly photosensitive viologen material.