Abstract
The conformational analysis of some amino acids derivatives, esterified and acetylated, as well as of some dipeptides is proposed. This is an advanced project in comparison to a previous one since it will focus on more complex structures and also on the application of the most recent theoretical methods, used in physical organic chemistry. The experimental work will be based in NMR spectroscopy (1H, 13C and 15N) and in infrared spectroscopy. The theoretical calculations will be performed at MP2 and DFT level of theory, using several basis sets, and including Zero-Point corrections (ZPE), which will provide the energies and geometries of the most stable conformers in the isolated form. Calculations using the IEF-PCM model will give similar data for these compounds in several solvents. The analysis of the carbonyl band (fundamental and 1st overtone) in several solvents will give the populations of the more stable rotamers in solution. The NMR spectra will provide JHH coupling constants, geminal and vicinal, involving the CH and CH2 groups, in solution, which can indicate changes in conformer populations according to the permittivity of the solvent. Values obtained from theoretical calculations of the carbonyl stretching vibration and of the coupling constants, in the studied solvents, will be compared with the experimental data in the assessment of the populations of the more stable conformers. Lastly, the contributions of the classical intramolecular interactions (steric and electrostatic) and quantum interactions (hyperconjugation) to stabilize a given conformer will be evaluated through topological analyses from the Quantum Theory of Atoms in Molecules (QTAIM), Non Covalent Interactions (NCI) and Electron Localization Function (ELF) and also the Natural Bond Orbitals (NBO) analysis. A joint analysis with these techniques may allow unequivocally the main effects which are responsible for the conformer stabilities of these important systems. (AU)
Scientific publications
(10)
(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)
BATISTA, PATRICK R.;
KARAS, LUCAS J.;
VIESSER, RENAN V.;
DE OLIVEIRA, CYNTHIA C.;
GONCALVES, MARCOS B.;
TORMENA, CLAUDIO F.;
RITTNER, ROBERTO;
DUCATI, LUCAS C.;
DE OLIVEIRA, PAULO R.
Dealing with Hydrogen Bonding on the Conformational Preference of 1,3-Aminopropanols: Experimental and Molecular Dynamics Approaches.
Journal of Physical Chemistry A,
v. 123,
n. 40,
p. 8583-8594,
OCT 10 2019.
Web of Science Citations: 0.
CORMANICH, RODRIGO A.;
KEDDIE, NEIL S.;
RITTNER, ROBERTO;
O'HAGAN, DAVID;
BUEHL, MICHAEL.
Particularly strong C-H center dot center dot center dot pi interactions between benzene and all-cis 1,2,3,4,5,6-hexafluorocyclohexane.
Physical Chemistry Chemical Physics,
v. 17,
n. 44,
p. 29475-29478,
2015.
Web of Science Citations: 10.