Rhodamine 6G salicylaldehyde hydrazone-Zn complex: Synthesis, characterization, photochromism, understanding, and application

Zinc complex-based photochromic materials are gaining significant interest from their applications in various consumer products such as toys, cosmetic products, photochromic inks (for security marking), data storage, erasable optical memory media, etc. Here, the rhodamine 6G salicylaldehyde hydrazone-Zn complex was synthesized, characterized, and understood to develop a molecular device. The crystal structure analysis (CCDC number 2260405) confirms the synthesis of a new photo-ligand, rhodamine 6G salicylaldehyde hydrazone. The NMR, ESI-Mass, FT-IR, UV–Vis spectra (Job's and Benesi Hildebrand plots), chelation-enhanced fluorescence spectra (CHEF), and geometry optimization confirm the synthesis of the Zn-complex. We have studied photochromic behavior with absorption, emission, fatigue resistance, role of solvents, thermal bleaching kinetics, FMO computation, and vibrational analysis. The vibrational analysis has rationalized excited state intramolecular proton transfer (ESIPT) involved in photochromism. An attempt has been made to construct photochromic devices.