Photochromic and molecular switching behaviour of Schiff base-containing pyrazolone ring

A new Schiff base compound, 4-[[(5-hydroxy-3-methyl-1-phenyl-1 H -pyrazol-4-yl)methylidene] amino]-1,5-dimethyl-2-phenyl-2,3-dihydro-1 H -pyrazol-3-one ( I ), was synthesised and characterised by elemental analysis and LC-MS, FTIR and 1 H NMR spectra. The photochromic property of the synthesised compound investigated under 365 nm UV irradiation can be observed by solid state absorption and fluorescence spectra. The kinetic study showed that the photochromic reaction was of the pseudo-first-order. The photo-isomerisation was due to photo-induced intermolecular hydrogen bonding, which resulted in enol to keto transformation. The molecular switching behaviour was studied in solution with two inputs in three different systems (OH − and Ag + ), (OH − and Cd 2+ ) and (OH − and Th 4+ ) based on the UV absorption spectra. It exhibited the logic behaviour of XNOR, AND and NOR for Ag + ,Cd 2+ and Th 4+ in alkaline media, respectively.