An experimental and theoretical study on the hydration in aqueous medium of the antihypertensive agent tolazoline hydrochloride

► Tolazoline hydrochloride in aqueous medium was characterized by IR and Raman spectra. ► The monocation, chloride and dimeric structures in aqueous solution were studied. ► The solvent effects were investigated by using the Onsager and PCM models. ► The monocation, chloride and dimeric forms were detected in the IR spectrum. ► The topological properties for the three structures were studied.