Au(III)-complexes of the alanyl-containing peptides glycylalanine and glycylalanylalanine – Synthesis, spectroscopic and structural characterization

Abstract

As part of an investigation on the coordination ability of peptides, the dipeptide glycylalanine ( H- Gly- Ala- OH), tripeptide glycylalanylalanine ( H- Gly- Ala- Ala- OH) and their Au(III)-complexes have been characterized structurally. The quantum chemical calculations and linear-dichroic infrared (IR-LD) spectroscopy predict structures of the compound studied, which are compared with a single crystal X-ray diffraction of H- Gly- Ala- OH. The coordination processes with Au(III) are supported by data for 1H NMR, ESI-MS, HPLC–MS–MS, TGV and DSC methods. The [Au( Gly- Ala)H −1Cl] and [Au( Gly- Ala- Ala)H −2] · 2H 2O complexes are formed via –NH 2, N −amide/s and CO 2 - groups of the peptides. One Cl − ion is attached to the metal center as terminal ligand in the first complex. In both cases a near to square-planar geometry of the chromophors AuN 2OCl and AuN 3O is yielded.