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Conformational study of arbutin by quantum chemical calculations and multivaria...
Araujo-Andrade, Cuauhtémoc; Lopes, Susy; Fausto, Rui; Gómez-Zavaglia, AndreaA conformational study of the molecule of arbutin (4-hydroxyphenyl-β-d-glucopyranoside) has been undertaken. The molecule is composed by a glucopyranoside moiety bound to a phenol ring. It has eight conformationally relevant dihedral angles, five of them related with the orientation of the hydroxyl groups and the remaining three taking part in the skeleton of the molecule. A systematic search on the conformatio...
Conformational Space and Vibrational Spectra of Methyl 4-Chloro-5-phenyl-1,3-ox...
Lopes, Susy; Nunes, Cláudio M.; Gómez-Zavaglia, Andrea; Melo, Teresa M. V. D. Pinho e; Fausto, RuiMethyl 4-chloro-5-phenyl-1,3-oxazole-2-carboxylate (MCPOC) has been synthesized and isolated in cryogenic matrices (argon and xenon). FTIR spectroscopy studies on the matrix isolated compound, supported by DFT(B3LYP)/6-311++G(d,p) calculations, allow for the identification of two low-energy conformers (I and II) of the molecule, which differ from each other in the orientation of the ester group relative to the ...
Formic and acetic acids in a nitrogen matrix: Enhanced stability
Lopes, Susy; Domanskaya, Alexandra V; Fausto, Rui; Räsänen, Markku; Khriachtchev, LeonidFormic acid HCOOH, FA and acetic acid CH3COOH, AA are studied in a nitrogen matrix. The infrared IR spectra of cis and trans conformers of these carboxylic acids and also of the HCOOD isotopologue of FA are reported and analyzed. The higher-energy cis conformer of these molecules is produced by narrowband near-IR excitation of the more stable trans conformer, and the cis-to-trans tunneling decay is eval...
4-Halo-1,3-oxazoles: Unambiguous structural assignment of 2-halo-2-benzoyl-2H-a...
Lopes, Susy; Nunes, Cláudio M.; Fausto, Rui; Melo, Teresa M. V. D. Pinho ehttp://www.sciencedirect.com/science/article/B6TGS-4T9CD1T-2/2/97ced5a20f3a7c031b52a8483cc8ee76
Spectroscopic and theoretical investigation of the conformational space of a py...
Nunes, Cláudio M.; Lopes, Susy; Melo, Teresa M. V. D. Pinho e; Fausto, Ruihttp://www.sciencedirect.com/science/article/B6TGS-4V88FW3-1/2/a0eb253493e1ccafe49b75247f2ded74
Low temperature IR spectroscopy and photochemistry of matrix-isolated [alpha]-p...
Lopes, Susy; Gómez-Zavaglia, Andrea; Fausto, Ruihttp://www.sciencedirect.com/science/article/B6TGY-4T13CK1-2/2/4df8d8878fb0679a9b922d8db211de67
Low temperature IR spectroscopy and photochemistry of matrix-isolated α-pyridil
Lopes, Susy; Gómez-Zavaglia, Andrea; Fausto, Ruiα-Pyridil [(C6H4NO)2] has been isolated in low temperature argon and xenon matrices and studied by FTIR spectroscopy, supported by DFT(B3LYP)/6–311++G(d,p) calculations. Calculations predicted the existence of three different conformers exhibiting skewed conformations around the intercarbonyl bond and the two C5H4NC(O) fragments nearly planar. The two higher energy forms, TCG and CCSk were estimated theoretical...
Matrix isolation and low temperature solid state FTIR spectroscopic study of al...
Lopes, Susy; Gómez-Zavaglia, Andrea; Fausto, RuiAlpha-furil [C(4)H(3)O-C(=O)-C(=O)-C(4)H(3)O] has been isolated in argon and xenon matrices and studied by FTIR spectroscopy, supported by DFT(B3LYP)/6-311++G(d,p) calculations. The obtained spectra were fully assigned and revealed the presence in the matrices of three different conformers, all of them exhibiting skewed conformations around the intercarbonyl bond with the two C(4)H(3)O-C(=O) fragments nearly pl...
Conformational Flexibility, UV−Induced Decarbonylation, and FTIR Spectra of 1-P...
Lopes, Susy; Gómez-Zavaglia, Andrea; Lapinski, Leszek; Fausto, Rui1-Phenyl-1,2-propanedione has been isolated in low-temperature xenon matrixes and studied by FTIR spectroscopy, supported by DFT(B3LYP)/6-311++G(d,p) calculations. In good agreement with previous electron diffraction data [Shen, Q.; Hagen, K. J. Phys. Chem. 1993, 97, 985], the calculations predicted the existence of only one stable conformation for the compound, in which the OCCO dihedral angle is 135.6°. On th...
Molecular structure and infrared spectra of dimethyl oxalate
Lopes, Susy Branco; Lapinski, Leszek; Fausto, RuiInfrared spectra of dimethyl oxalate isolated in low-temperature argon matrix and of the compound in the solid amorphous and crystalline state are reported. The experimental observations are interpreted in terms of a large amplitude, low frequency vibration along the torsional coordinate OC–CO. Assumption of the large amplitude vibration allows consistent explanation of the spectra observed in matrixes and in t...
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