Conformational equilibria and intramolecular interactions for a series of amino-acids: theoretical and experimental approaches

• Grant number: 12/03933-5
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2012
• End date: August 31, 2014
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: Roberto Rittner Neto
• Grantee: Roberto Rittner Neto
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

This project involves the study of the conformational analysis of several aminoacids as well as models of dipeptides (N-acetyl-R-N-methylamide: R=glycine, alanine, valine, phenylalanine and tyrosine), through NMR spectroscopy (H-1, C-13 and N-15) and by infrared spectroscopy and theoretical calculations of electronic structure. The theoretical calculations will be performed at ab initio MP2 and Density Functional Theory (DFT) levels with several basis sets and with zero-point corrections (ZPE), which will give the geometries and energies of the stable conformers in the isolated state and in solution with the IEFPCM solvation model. The infrared spectra in the fundamental carbonyl stretching frequency and in the first overtone, in several solvents, will be used to determine the conformer population ratios. A detailed H-1 and C-13 NMR study will show if the J(HH)geminal and vicinal couplings between the hydrogen atoms of the CH and CH2 groups follow the changes in conformer populations. Theoretical calculations of the carbonyl stretching frequencies and coupling constants J(HX)(X=H, C or N) together with experimental data, in several solvents, will be used for the determination of the conformer populations. The contributions of the intramolecular interactions of classical nature (steric and elctrostatic) and of quantum origem (Hyperconjugation) for the conformational stability of these compounds, besides the above data, will be evaluated by topological analysis through the Quantum Theory of Atoms in Molecules (QTAIM), Electronic Localization Function (ELF) and Natural Bond Orbitals (NBO). The results obtained by all these techniques will show which are the main factors responsible for the conformational prefernces of these important compounds. (AU)

Scientific publications

(14)

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

ROZADA, THIAGO C.; GAUZE, GISELE F.; ROSA, FERNANDA A.; FAVARO, DENIZE C.; RITTNER, ROBERTO; PONTES, RODRIGO M.; BASSO, ERNANI A.. The conformational analysis of 2-halocyclooctanones. SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, v. 137, p. 176-184, FEB 25 2015. (12/03933-5)

SILLA, JOSUE M.; DUARTE, CLAUDIMAR J.; CORMANICH, RODRIGO A.; RITTNER, ROBERTO; FREITAS, MATHEUS P.. Conformational analysis of 2,2-difluoroethylamine hydrochloride: double gauche effect. Beilstein Journal of Organic Chemistry, v. 10, p. 877-882, APR 16 2014. (11/01170-1, 12/03933-5, 11/11098-6)

CORMANICH, RODRIGO A.; DURIE, ALASTAIR; BJORNSSON, RAGNAR; RITTNER, ROBERTO; O'HAGAN, DAVID; BUEHL, MICHAEL. Density Functional Study of Interactions between Fluorinated Cyclohexanes and Arenes. Helvetica Chimica Acta, v. 97, n. 6, p. 797-807, JUN 2014. (11/01170-1, 12/03933-5)

CORMANICH, RODRIGO A.; DUCATI, LUCAS C.; TORMENA, CLAUDIO F.; RITTNER, ROBERTO. Phenylalanine and tyrosine methyl ester intramolecular interactions and conformational analysis by H-1 NMR and infrared spectroscopies and theoretical calculations. SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, v. 123, p. 482-489, APR 5 2014. (11/01170-1, 12/03933-5)

BRAGA, CAROLYNE B.; DUCATI, LUCAS C.; TORMENA, CLAUDIO F.; RITTNER, ROBERTO. Conformational Analysis and Intramolecular Interactions of L-Proline Methyl Ester and Its N-Acetylated Derivative through Spectroscopic and Theoretical Studies. Journal of Physical Chemistry A, v. 118, n. 9, p. 1748-1758, MAR 6 2014. (12/18567-4, 12/03933-5)

DUARTE, CLAUDIMAR J.; CORMANICH, RODRIGO A.; DUCATI, LUCAS C.; RITTNER, ROBERTO. H-1 NMR and theoretical studies on the conformational equilibrium of tryptophan methyl ester. Journal of Molecular Structure, v. 1050, p. 174-179, OCT 24 2013. (11/01170-1, 12/03933-5, 11/11098-6)

DE MELO, ULISSES ZONTA; SILVA, RAI G. M.; YAMAZAKI, DIEGO A. S.; PONTES, RODRIGO M.; GAUZE, GISELE F.; ROSA, FERNANDA A.; RITTNER, ROBERTO; BASSO, ERNANI A.. NMR Spectroscopy and Theoretical Calculations in the Conformational Analysis of 1-Methylpyrrolidin-2-one 3-Halo-derivatives. Journal of Physical Chemistry A, v. 119, n. 10, p. 2111-2121, MAR 12 2015. (12/03933-5)

SILLA, JOSUE M.; FREITAS, MATHEUS P.; CORMANICH, RODRIGO A.; RITTNER, ROBERTO. The Reverse Fluorine Perlin-like Effect and Related Stereoelectronic Interactions. Journal of Organic Chemistry, v. 79, n. 13, p. 6385-6388, JUL 4 2014. (11/01170-1, 12/03933-5)

SILVA, THAYNA F. B.; ANDRADE, LAIZE A. F.; SILLA, JOSUE M.; DUARTE, CLAUDIMAR J.; RITTNER, ROBERTO; FREITAS, MATHEUS P.. Endocyclic Oxygen in 3-Fluorodihydro-2H-pyran-4(3H)-one That Does Not Induce the Gauche Effect. Journal of Physical Chemistry A, v. 118, n. 32, p. 6266-6271, AUG 14 2014. (11/11098-6, 12/03933-5)

CORMANICH, R. A.; RITTNER, R.; FREITAS, M. P.; BUEHL, M.. The seeming lack of CF center dot center dot center dot HO intramolecular hydrogen bonds in linear aliphatic fluoroalcohols in solution. Physical Chemistry Chemical Physics, v. 16, n. 36, p. 19212-19217, 2014. (11/01170-1, 12/03933-5)

SILLA, JOSUE M.; CORMANICH, RODRIGO A.; RITTNER, ROBERTO; FREITAS, MATHEUS P.. Does intramolecular hydrogen bond play a key role in the stereochemistry of alpha- and beta-D-glucose?. Carbohydrate Research, v. 396, p. 9-13, SEP 19 2014. (11/01170-1, 12/03933-5)

CORMANICH, R. A.; RITTNER, R.; BUEHL, M.. Conformational preferences of Ac-Gly-NHMe in solution. RSC ADVANCES, v. 5, n. 17, p. 13052-13060, 2015. (11/01170-1, 12/03933-5)

BRAGA, CAROLYNE B.; DUCATI, LUCAS C.; RITTNER, ROBERTO. Experimental and theoretical evaluation on the conformational behavior of L-aspartic acid dimethyl ester and its N-acetylated derivative. RSC ADVANCES, v. 5, n. 23, p. 18013-18024, 2015. (12/18567-4, 12/03933-5)

SCHUQUEL, IVANIA T. A.; DUCATI, LUCAS C.; TORMENA, CLAUDIO F.; DE FREITAS, MATHEUS P.; DE KOWALEWSKI, DORA G.; RITTNER, ROBERTO. C-13 NMR: (n)J(CH) and (1)J(CC) scalar spin-spin coupling constants (SSCCs) for some 3-monosubstituted 2-methylpropenes. Journal of Molecular Structure, v. 1068, p. 170-175, JUN 25 2014. (12/03933-5)