Study of copper(II)-glycylphenylalanine complex with ninhydrin in aqueous and cationic CTAB micellar media: A kinetic and mechanistic approach

The reaction of copper(II)-glycylphenylalanine ([Cu(II)-Gly-Phe](+)) with ninhydrin has been carried out in aqueous and cationic surfactant (cetyltrimethylammonium bromide, CTAB) at temperature (343 K) and pH (5.0). The reaction was followed by means of UV-Vis spectrophotometer. The reaction kinetics show first-order dependence on [Cu(II)-Gly-Phe](+) and fractional-order on [ninhydrin]. Studies were carried out on the influence of several variables on rates. CTAB surfactant strongly catalyzes the reactions. The values of rate constants (k(psi)) were observed higher in CTAB than aqueous. The catalytic effect of CTAB can be related to the extent of incorporation/association of the [Cu(II)-Gly-Phe](+) and ninhydrin into the micelles. Data obtained in micellar media are treated quantitatively in terms of pseudo-phase model of the micelles. (C) 2014 Elsevier B.V. All rights reserved.