Metal complexes as indicators for solvent structure. Part I. Nickel(II) complexes of meso-stilbenediamine or triethylenetetramine in mixed aqueous media

Abstract

The electronic spectra of solutions of salts of either the triethylenetetraminenickel(II) ions on the bis-m-stilbenediaminenickel(II) ion have been used to measure the ratio of the blue form (B) to the yellow form (Y) under various conditions (mixed solvents, added salts, temperature). log [Y]/[B] is proportional to a defined solvent molarity, and appears to give a method of evaluating structure-making (e.g. proteins) or breaking (e.g. urea) agents.