Solvatochromism in Urea/Water and Urea-Derivative/Water Solutions

This work reports experimental measurements of solvent acidity (SA), basicity (SB), and SPP (solvent dipolarity and polarizability) for the water mixtures with urea (U) and its molecular derivatives, monomethyl-urea (MU), 1,3-dimethyl-urea (DMU) and, tetramethyl-urea (TMU). These solvatochromic parameters are applied to understanding the variation of indexes of refraction and densities and other physico-chemical properties reported for these mixtures. These properties are well correlated against the SA, SB, SPP solvent parameters of these mixtures. As a result, from the characterization of the physico-chemical properties one can infer that urea and its molecular derivatives are mainly modifiers in the structure of liquid water. The solvatochromic parameters indicate possibly the existence of different mechanisms in the denaturing process of proteins with these urea/water mixtures.