Kinetics of the Racemization and Dissociation of Tris(1,10-phenanthroline)iron(II) and Tris(2,2′-bipyridine)iron(II) in Sodium Dodecyl Sulfate Solutions

Abstract

Abstract The kinetics of the racemization and dissociation of [Fe(phen)3]2+ (phen=1,10-phenanthroline) and [Fe(bpy)3]2+ (bpy=2,2′-bipyridine) was investigated in aqueous sodium dodecyl sulfate (SDS) solutions. The racemization and dissociation rates of the complexes increased with the increase in the SDS concentration to reach limiting values at concentrations above the critical micelle concentration (cmc). The rate changes occurring below the cmc were explained in terms of the formation of at least three kinds of premicellar aggregates of the complex ion with dodecyl sulfate ions. In the region slightly above the cmc, where the concentration of the complex ion is larger than that of the micelle, the rates continued to increase with the increase in the micellar concentration, suggesting that the complex ions interacted with the micelles. A comparison of the kinetic behavior in aqueous micellar solutions with that in organic solvents revealed that the complexes were located inside the micelle–water interface. The mechanisms of the acceleration in the micelle were discussed.