Spectroscopic and Electrochemical Analysis of Interaction of DBCH2 with Iron(III) complexes of N-Salicylidene-L-amino Acids in Aqueous Surfactant Micelle Medium

Interaction of Iron(III) complexes of N-Salicylidene-L-amino Acids (i.e., [Fe(sal-L-his)]Cl.H₂O and [Fe(sal-L-ala)]Cl.H₂O) with catecholate substrate encapsulated in aqueous surfactant micelle has been projected as functional model of dioxygenase enzyme. Biomimetic environment for the study has been provided by the aqueous surfactant medium. Micellization of the complexes are studied by electrochemical and spectroscopic analysis and the cmc values are within 5.0 × 10^-4 - 2.0 × 10^-3 M. When ferric complexes are interacted with a catecholate anion (DBCH^-) with 2 equivalent of base, a band at 360.6 nm (ε, 5010 M^-1 cm^-1) and a weak band around 480-520 nm are observed and it suggests monodentate coordination of catechol ion-to-iron(III). On addition of excess base (4 equivalents) two catecholto-iron(III) (DBC^2--Fe) LMCT bands at 400.2 nm (ε, 5022 M^-1 cm^-1) and 608 nm (ε, 2000 M^-1 cm^-1) are developed corresponding to the bidentate coordination of ligand. In micellar medium, the redox potential of DBSQ/DBCH₂ couple is significantly more positive than that (-0.890V, NHE) of free DBCH₂, it reflects stabilization of DBCH₂ by chelation to ferric centre.