Solvatochromism, Hydrogen Bonding Induced Charge Transfer, and Influence of pH on Electronic Absorption Spectra of Murexide

A study of the solvent effect was used to describe the pronounced change in position of the UV-Visible absorption band associated with changing the polarity of the medium. Murexide compound which has different position of UV-Visible absorption band in the protic and nonprotic solvents. Various solvent parameters, such as dielectric constant, refractive index, Kamlet–Taft and Catalán parameters were used for the evaluation of the solute–solvent interactions and the solvatochromic shifts of the UV-Vis absorption maximum of the investigated indicator. The phenomenon of tautomerism is explained. The Kamlet–Taft solvent scale was found to be the most appropriate to describe the solvatochromic behavior of the Murexide. The dissociation constant pK a and the isosbestic point of the investigated compound showed the presence of the individual predominate ionic species in different pH ranges.