Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical StudyReport as inadecuate




Structural, Vibrational, and Electronic Properties of the Glucoalkaloid Strictosidine: A Combined Experimental and Theoretical Study - Download this document for free, or read online. Document in PDF available to download.

Journal of Chemistry - Volume 2016 2016, Article ID 1752429, 16 pages -

Research Article

Department of Chemistry, Federal University of Amazonas, 69077-000 Manaus, AM, Brazil

NMR Laboratory, Department of Chemistry, Federal University of Paraná, 80060-000 Curitiba, PR, Brazil

National Research Institute of Amazonas INPA, 69080-971 Manaus, AM, Brazil

Received 21 October 2015; Accepted 3 January 2016

Academic Editor: Arturo Espinosa Ferao

Copyright © 2016 Renyer Alves Costa 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

A detailed structural analysis and spectral behavior of the glucoalkaloid strictosidine, a precursor of all monoterpene indole alkaloids, are discussed. The experimental NMR, FTIR, and UV results were compared to the theoretical DFT spectra calculated by Becke using the three-parameter Lee-Yang-Parr B3LYP function with 6-31Gd and 6-311++G2d,p basis sets. The theoretical geometry optimization data were compared with the X-ray data for precursors and similar structures in the associated literature. The similarity between the theoretical and experimental coupling constants values made it possible to affirm the values of dihedral angles and their configuration, reinforcing findings from previous stereochemical studies. Theoretical UV analysis agreed well with the measured experimental data, with bands assigned. Calculated HOMO-LUMO gaps show low excitation energy for strictosidine, justifying its stability and reaction kinetics. The molecular electrostatic potential map shows opposite potentials regions that form hydrogen bonds that stabilize the dimeric form, which were confirmed by excellent agreement of the dimeric form theoretical wavenumbers with the experimental IR spectrum. ESI-MS-MS data revealed patterns for the fragmentation of the protonated strictosidine molecule outlined by an NBO study.





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