Encontrados 26 documentos, a visualizar página 1 de 3
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 and structural analysis of 2-allyl-1,2-benzisothiazol-3(2H)-one ...
Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Coelho, Daniela; Cristiano, M. Lurdes S.; Fausto, Ruihttp://www.sciencedirect.com/science/article/B6TGS-4THC1JN-1/2/1228ea86baa026383b4037e881569263
First observation of Chapman rearrangement of a pseudosaccharyl ether in the so...
Almeida, R.; Gómez-Zavaglia, Andrea; Kaczor, A.; Cristiano, M. L. S.; Eusébio, M. E. S.; Maria, T. M. R.; Fausto, R.3-(Methoxy)-1,2-benzisothiazole 1,1-dioxide, a pseudosaccharyl ether, was long ago known to undergo a thermal Chapman-like [1,3']-isomerization to the corresponding N-methyl pseudosaccharin at temperatures above its melting point (ca. 184 °C) [Hettler H., Tetrahedron Lett. 1968, 15, 1793]. In the present study, it is shown that this rearrangement can also take place in the solid state, at temperatures as low as...
Molecular structure and infrared spectra of the monomeric 3-(methoxy)-1,2-benzi...
Kaczor, Agnieszka; Almeida, Rui; Gómez-Zavaglia, Andrea; Cristiano, Maria de Lurdes S.; Fausto, RuiThe computational description of saccharin (1,2-benzisothiazol-3(2H)-one-1,1-dioxide) and its derivatives is difficult due to the presence of hypervalent SO bonds in their structures. Therefore, in this investigation, the HF, DFT/B3LYP and MP2 methods were used to predict the geometry and the infrared spectrum of the saccharyl derivative 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID). Their relative predict...
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
Conformational Space of the Pseudosaccharin Allyl Ether 3-(Allyloxy)-1,2-benzis...
Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Almeida, Rui; Cristiano, Maria de Lurdes S.; Fausto, RuiIn this work, the conformational space of the pseudosaccharyl ether 3-(allyloxy)-1,2-benzisothiazole 1,1-dioxide (ABID) has been studied by means of infrared spectroscopy and density functional theory (DFT) calculations. Five different low energy conformers (TSk, TC, GSk, GSk‘ and GC, with relative energies of 0.00, 1.97, 2.00, 3.82 and 6.02 kJ mol-1, respectively) were found on the DFT(B3LYP)/6-311++G(3df,3pd)...
Molecular structure and infrared spectra of the monomeric 3-(methoxy)-1,2-benzi...
Kaczor, Agnieszka; Almeida, Rui; Gómez-Zavaglia, Andrea; Cristiano, Maria de Lurdes S.; Fausto, RuiThe computational description of saccharin (1,2-benzisothiazol-3(2H)-one-1,1-dioxide) and its derivatives is difficult due to the presence of hypervalent SO bonds in their structures. Therefore, in this investigation, the HF, DFT/B3LYP and MP2 methods were used to predict the geometry and the infrared spectrum of the saccharyl derivative 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID). Their relative predict...
Dimer formation in nicotinamide and picolinamide in the gas and condensed phase...
Borba, Ana; Albrecht, Merwe; Gómez-Zavaglia, Andrea; Lapinski, Leszek; Nowak, Maciej J.; Suhm, Martin A.; Fausto, RuiAggregation of nicotinamide (3-pyridine-carboxamide; NA) and picolinamide (2-pyridine-carboxamide; PA) has been investigated by matrix-isolation, supersonic jet and neat solid state infrared spectroscopy, complemented by DFT(B3LYP)/6-311++G(d,p) calculations. For both compounds, the most stable dimeric structure was shown to be the centrosymmetric dimer where two monomers in their most stable forms establish tw...
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...
Molecular Structure, Vibrational Spectra, Quantum Chemical Calculations and Pho...
Borba, Ana; Gómez-Zavaglia, Andrea; Fausto, R.Picolinamide (PA) and isonicotinamide (INA), two structural isomers of pyridinecarboxamide, have been investigated by matrix isolation and low-temperature solid-state infrared spectroscopy, combined with UV (λ > 235 nm) photoexcitation and density functional theory and ab initio (MP2) theoretical studies. In consonance with the theoretical data, both PA and INA were found to exist in a single conformation in cr...
| Financiadores do RCAAP | |||||||
|
|
|
|
|
|
||