Stimulus-responsive multifunctions in a zinc(ii) sulfate complex: photochromism, photoswitching nonlinear optical properties, amine detection and visual film application

Abstract

Stimulus-responsive functional materials show broad applications in the fields of sensing, optical switching and energy conversion devices. Herein, a one-dimensional chain compound constructed from the electron-deficient rigid polypyridine ligand 2,4,6-tri(4-pyridyl)-1,3,5-triazine and electron-rich sulfate was successfully synthesized with reversibly electron transferred photochromic and photoluminescent behaviors. Second-harmonic generation (SHG) active behavior studies showed that the compound exhibits photomodulation of nonlinear optical properties with an impressive high SHG-switching contrast (ca. 6 times) before and after light irradiation. Furthermore, this compound exhibited selectively vapochromic behavior in response to different amines, allowing its application in a visual recognition detector for specific amines. Based on the photochromic and photoluminescent properties, applications in inkless printing and information encryption were successfully demonstrated. This work shows a facile way to obtain sulfate-based compounds with stimulus-responsive multifunctions, expanding the repertoire of multifaceted chromic materials for advanced visual chromic sensors.