Photochromism of dye containing Schiff base-metal complex: A revisit through spectro-kinetic, thermodynamic and theoretical analyses for the design of a molecular logic gate

•A unique photochromic coordination complex has been designed and developed.•The dye containing Schiff base zinc complex shows remarkable photochromic properties.•The photochromism is basically photo-thermal reversible process, not photo-equilibrium.•The photochromism follows metal-guided excited-state intramolecular proton transfer.•DFT studies leads to a clear understanding of metal guided photochromism (MG-ESIPT).