Abstract
Adduct formation of ternary Pt(II) complexes composed of an amino acid and an aromatic diimine, [Pt(A)(DA)] (A = glycinate (Gly), alaninate (Ala), valinate, or arginine (Arg); DA = 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen)), with flavin mononucleotide (FMN) and anthraquinone-2-sulfonate (AQS) were investigated by spectroscopic, X-ray diffraction, and electrochemical methods. The Pt(II) complexes formed 1:1 [Pt(A)(DA)]–FMN adducts by stacking with the aromatic moiety of FMN, and the stability constants, log K, for the systems with [Pt(A)(phen)] (A = Gly, Ala, and Arg) and [Pt(Arg)(bpy)] were determined to be 2.83(8)–3.42(6) from 1H NMR spectra at 25 °C in D 2O ( I = var.). The structure of the adduct [Pt(Ala)(phen)](AQS) ( 1) was determined by X-ray analysis to involve a π–π stacking interaction between coordinated phen and AQS with the distance of 3.400(7) Å and a hydrogen bond between the sulfonate moiety of AQS and the amino group of coordinated Ala. Cyclic voltammetry of the 1:1 [Pt(A)(DA)]–FMN systems in a phosphate buffer (pH 7.0) showed that the potentials, E 1/2, for the two-electron redox process of FMN shifted to higher values by 18–31 mV as compared with the value for free FMN.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have