The effect of zinc ion on the absorption and emission spectra of glutathione derivative: Predication by ab initio and DFT methods

► The rigidity of the GSH-OPA could be increased by electrostatic interaction with Zn2+ ion. ► Coordination of Zn2+ to GSH-OPA gives rise to a new ligand-to-metal charge transfer transition. ► The emission at about 380 nm of GSH-OPA-Zn can be assigned to the GSH-OPA intraligand π* → π transition. ► The effects of water and methanol on the emission spectra of GSH-OPA and GSH-OPA-Zn are not obvious.