The photo/electrochromic properties of a Cd(II)-viologen and its application in fluorescence detection of tryptophan, inkless printing and information transmission

Abstract

Currently, viologen-based complexes are widely used in the study of photochromic and thermochromic properties. However, viologen-based complexes are rarely used in the study of fluorescent probes, especially probes for the detection of amino acids. Herein, a novel three-dimensional (3D) Cd-based framework ([Cd(cbpc)_0.5(PTA)]_n (1)) was constructed by the solvothermal method using the viologen ligand 1-(3-Carboxybenzyl)-4,4′-bipyridyl chloride (H₂cbpc) and isophthalic acid (H₂PTA) as organic functional building units. Complex 1 exhibits a high-contrast discoloration behavior through electron transfer when subjected to external stimuli (light and electricity), and the color of complex 1 changes from light yellow to light black and purple-black, respectively. It is noteworthy that complex 1 exhibits a rapid detection process of tryptophan in an aqueous environment, and displays an excellent low detection limit (LOD) and high anti-interference capability. Furthermore, complex 1 can be employed in inkless printing, information anti-counterfeiting and other light-mediated applications.