Solvent effects on the absorption spectra of arginine-salicylaldimine

► Synthesis of arginine-salicylaldimine, characterization and its absorption spectra in various solvents were studied. ► The molecule shows keto-enol tautomerism and acid-base equilibrium; keto form predominates in non-polar solvents. ► pka of aqueous equilibrium species. ► In a mixed-solvent system (CH2Cl2-methanol), there is a strong preference for the molecule to interact with methanol. ► TD-DFT calculations shows π→π* electronic transitions for the keto and enol forms in the 370-440 nm region.