intramolecular H-bond) or an anionic (1c) form.The ESIPT process to form excited 1b and solvent-mediated ground-state formation of anion depend strongly on the concentration of the drug in alcohols.At a high concentration of 1 (10-4 to 10-2 M), the ESIPT is the dominant process, whereas at the low concentration the excited-state conformational change of anion to a zwitterionic (1d) form was observed