Photoelectron spectroscopy of biologically active molecules. 21. Thiooxamides

Abstract

The He1 photoelectron ( PE) spectra of No,No-dimethyl-monothiooxamide ( l ) , its analogue N S , NSdimethylmonothiooxamide (2), dithiooxamide (3), N,N'-dimethyldithiooxamide (4), and N, N , N',N'-tetramethyldithiooxamide ( 5 ) are presented. The results of CND0/2 calculations, the PE spectra of the related compounds acetamide, thioacetamide, thiourea, and their methyl derivatives, and HeI/HeII intensity considerations are used to assign the spectra.

Photoelectron Spectra of Some Important Biological Molecules: Symmetry-Adapted-Cluster Configuration Interaction Study

“…Valence ionization of biologically active compounds gives information about the frontier orbitals which significantly change in the species and chemical reactions. In this regard, there are numerous gas-phase He-I and He-II photoelectron spectra of different biological molecules in the literature. − Recently, photoelectron spectroscopy with the aid of high level of computational chemistry has significantly contributed to the determination of the vertical ionization energies and elucidation of the structure and dynamic of biomolecules and their solvated complexes in the gas phase. − For example, photoelectron spectroscopy along with the ab initio calculations was employed to determine the population ratios of different conformers and tautomers of amino acids and nucleotides in the gas phase . In another example, effect of solvation on the vertical ionization energies of amino acids and nucleotides in microhydration and bulk conditions has been also investigated both experimentally and theoretically. , …”