Vibrational and Structural Behavior of l‑Cysteine Ethyl Ester Hydrochloride in the Solid State and in Aqueous Solution

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2013-12, Vol.117 (51), p.14243-14252
• Main Authors: Defonsi Lestard, M. E, Díaz, S. B, Puiatti, M, Echeverría, G. A, Piro, O. E, Pierini, A. B, Altabef, A. Ben, Tuttolomondo, M. E
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Density-functional theory; Electronic structure of atoms, molecules and their ions: theory; Electronics; Ethyl esters; Exact sciences and technology; Hydrochlorides; Molecular dynamics; Molecular properties and interactions with photons; Molecular spectra; Optical activity and dichroism; magnetooptical and electrooptical spectra; Optical activity, optical rotation; circular dichroism; Orbitals; Physics; Raman and rayleigh spectra (including optical scattering); Solvation; Spectra
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp409252d

The aim of this work is to evaluate the vibrational and structural properties of l-cysteine ethyl ester hydrochloride (CE), and its electronic behavior mainly in relation to the action of the thiol and amine groups at different degrees of solvation. The crystal structure of CE was determined at room temperature by X-ray diffraction methods. Infrared and Raman spectra were collected to compare the behavior of different functional groups in the molecule, both in the solid phase and in aqueous solution. Its UV and circular dichroism spectra were also measured in aqueous solution. The influence of an aqueous environment on the CE spectra was simulated by means of implicit (polarizable continuum model) and explicit (molecular dynamics, solute–solvent clusters) methods. Calculations in explicit and continuous solvent are of interest to explain the behavior of bioavailable sites in this medium. The study was completed by natural bond orbital analysis to determine the presence of hyperconjugative interactions.