Table of Contents
ISRN Spectroscopy
Volume 2012 (2012), Article ID 517837, 13 pages
http://dx.doi.org/10.5402/2012/517837
Research Article

New Di- and Triorganotin(IV) Tyrosylalaninates as Models for Metal—Protein Interactions: Synthesis, Structural Characterization, and Potentiometric Studies of Tyrosylalanine, Glycyltyrosine, and Glycylisoleucine with Di- and Trimethyltin(IV) Moieties in Aqueous Medium

1Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India
2Department of Chemistry and Physics, University of the District of Columbia, Washington, DC 20008, USA

Received 6 January 2012; Accepted 1 February 2012

Academic Editors: L. Jerzykiewicz and M. I. M. Wazeer

Copyright © 2012 Mala Nath et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Di- and triorganotin(IV) derivatives of tyrosylalanine (H2Tyr-Ala) with general formula R2Sn(Tyr-Ala) (where R = Me, n-Bu, n-Oct, and Ph) and R3Sn(HTyr-Ala) (where R = Me and Ph) have been synthesized and structurally characterized in the solid state as well as in solution on the basis of various spectroscopic techniques, namely. FT-IR, multinuclear (1H, 13C and 119Sn) NMR and 119Sn Mössbauer. These investigations suggest that tyrosylalanine in R2Sn(Tyr-Ala) acts as dianionic tridentate ligand coordinating through carboxylate oxygen [–C(O)O], amino (–NH2), and (CO)Npeptide nitrogen, while in the case of R3Sn(HTyr-Ala), the ligand acts as monoanionic bidentate coordinating through –C(O)O and –NH2, and the polyhedron around tin in R2Sn(Tyr-Ala) and R3Sn(HTyr-Ala) is a distorted trigonal-bipyramidal. Equilibrium (pH-metric) studies of the interaction of Me2Sn(IV)2+ and Me3Sn(IV)+ with dipeptides namely, tyrosylalanine (H2Tyr-Ala), glycyltyrosine (H2Gly-Tyr), and glycylisoleucine (H2Gly-Ile), in aqueous solution (I = 0.1 M KNO3, 298 K) have also been carried out. The concentration distribution of the various complex species in solution has been evaluated as a function of pH. It has been found that in these dipeptides, [–C(O)O, N, NH2] coordinated complexes are dominant in the neutral pH range with a trigonal-bipyramidal structure. The complex species formed are water soluble in the pH range 2.7–10.5. In all of the studied systems, no polymeric species have been detected in the experimental pH range. Beyond pH 8.0, significant amounts of hydroxo species, namely. Me3Sn(OH) and Me2Sn(OH)2, are formed.