Photochromic, fluorescence modulation and inkless printing of a zinc(II) inorganic–organic hybrid material based on 2,3-pyridinecarboxylic acid

Abstract

An inorganic–organic hybrid material [Zn(2,3-pydc)(H2O)2]n (1) was synthesized with 2,3-pyridinecarboxylic acid (2,3-H2pydc) and Zn(NO3)2·6H2O by solvothermal method. Compound 1 exhibits reversible photochromism between pale yellow and blue. The electron-transfer photochromism of 1 was verified by UV–vis, EPR and XPS spectra. The electron was transferred from carboxylate to pyridine ring upon irradiation. It is worth noting that unlike the luminescence quenching of normal photochromic materials via photoinduced coloration, the emission intensity of 1 can be obviously enhanced in the process of electron-transfer photochromism. 1 was found to display a long charge-separated state with a lifetime value of more than 6 months, exceeding the most reported values of the analogues. It endows potential to be applied in inkless printing.