The first 2,6-di(1,6-naphthyridin-2-yl)pyridine-based redox photochromic coordination polymer platform with selective vapochromism for trolamine

Abstract

The design and fabrication of crystalline photoswitchable materials play highly crucial roles for potential multidisciplinary applications. Good optimizations of the self-consistent donor–acceptor pair and skillful utilizations of weak intercomponent interactions are of great importance for redox photochromic coordination polymers (CPs). Herein, a novel redox chromic CP system with the photosensitive 2,6-di(1,6-naphthyridin-2-yl)pyridine (L) ligand has been developed for the first time, which contains a metallomacrocycle-based layer, a bent Z-shaped chain and a robust framework. Due to the photo-irradiated electron transfer, these CPs exhibit reversible color changes from yellow to green, colorless to blue and pale yellow to orange within an extremely short time. More interestingly, the photochromic framework can selectively and sensitively recognize volatile trolamine vapor through visible vapochromism resulting from quenching of the free radicals by the electron-enriched amino group. As compared with two low-dimensional CPs, the metal-assistant short contacts and intramolecular π⋯π interaction between benzenedicarboxylate and L is cooperatively responsible for the high-efficiency sensing. These findings present a new dual photochromic and vapochromic CP platform enabling visualized detection for electron-rich vapors.