Encontrados 9 documentos, a visualizar página 1 de 1
Molecular structure and vibrational spectra of 2(5H)-furanone and 2(5H)-thiophe...
Breda, S.; Reva, I.; Fausto, R.The structure and vibrational spectra of two five-membered heterocyclic [alpha]-carbonyl compounds have been studied. The experimental FTIR spectra 2(5H)-furanone and 2(5H)-thiophenone monomers isolated in inert argon matrices at 10 K are reported and discussed. The interpretation of the experimental data is supported by vibrational calculations at the MP2 and DFT(B3LYP) levels of theory with the 6-311++G(d,p) ...
In situ direct photoproduction of ketenes from substituted coumarins isolated i...
Kuş, N.; Breda, S.; Fausto, R.In this study, the infrared spectrum of N-(2-oxo-2H-chromen-3-yl)acetamide (3-acetamidocoumarin; 3AC) isolated in solid argon, at 10 K, was obtained and assigned. In consonance with the relative energies of the three conformers predicted theoretically, only the most stable form was observed experimentally. This conformer is stabilized by two intramolecular hydrogen bonds and is similar to the structural unit of...
UV-induced unimolecular photochemistry of 2(5H)-furanone and 2(5H)-thiophenone ...
Breda, S.; Reva, I.; Fausto, R.Monomers of two simplest five-membered heterocyclic α-carbonyl compounds, 2(5H)-furanone and 2(5H)-thiophenone were isolated in low temperature inert argon matrices and their UV-induced photochemistry was studied. The reaction photoproducts were identified by FTIR spectroscopy and interpretation of the experimental results was assisted by theoretical calculations of the infrared spectra at the DFT(B3LYP)/6-311+...
Molecular Structure, Infrared Spectrum, and Photochemistry of Squaric Acid Dime...
Breda, S.; Reva, I.; Lapinski, L.; Fausto, R.Squaric acid dimethyl ester (C6O4H6; 3,4-dimethoxycyclobut-3-ene-1,2-dione; DCD) was studied by matrix isolation infrared spectroscopy and by density functional theory (B3LYP) and ab initio (MP2) calculations with the 6-31++G(d,p) and 6-311++G(d,p) basis sets. Three conformers of the compound were theoretically predicted. The two most stable conformers were identified in low-temperature argon matrixes and the e...
Photochemical Ring-Opening and Intramolecular Hydrogen Shift Reactions in Sulfu...
Breda, S.; Reva, I.; Lapinski, L.; Cristiano, M. L. S.; Frija, L.; Fausto, R.A combined matrix isolation FTIR and theoretical DFT(B3LYP)/6-311++G(d,p) study of the photochemistry of sulfur analogues of α-pyrone [2H-thiopyran-2-one (TP) and 2H-pyran-2-thione (PT)] was carried out. The vibrational spectra of monomers of the compounds isolated in low-temperature argon matrixes were studied experimentally and assigned completely on the basis of theoretical calculations. UV irradiation (λ > ...
Infrared spectra of pyrazine, pyrimidine and pyridazine in solid argon
Breda, S.; Reva, I. D.; Lapinski, L.; Nowak, M. J.; Fausto, R.The vibrational spectra of monomeric diazines (pyrazine, pyrimidine and pyridazine) isolated in solid argon and of the neat crystalline phase of these compounds, at 10 K, are reported and discussed. Full assignment of the spectra is presented, providing evidence that the assignments of several bands previously undertaken for the compounds under other experimental conditions (e.g., gas phase, neat liquid or solu...
Matrix isolation FTIR and theoretical study of a-pyrone
Breda, S.; Reva, I.; Lapinski, L.; Fausto, R.A combined matrix isolation FTIR and molecular orbital study on the photochemistry of alpha-pyrone (AP) was undertaken. The most efficient of the observed photoprocesses was the Norrish type I, ring opening reaction leading to conjugated ketene. Upon irradiation of matrix isolated AP with UV (λ>285 nm) light, rapid formation of Z isomers of the aldehyde–ketene was observed. After a few minutes of irradiation th...
4,6-Dimethyl-α-pyrone: a matrix isolation study of the photochemical generation...
Breda, S.; Lapinski, L.; Reva, I.; Fausto, R.A combined matrix isolation and molecular orbital study of the vibrational spectra and photochemistry of 4,6-dimethyl-α-pyrone (DMAP) was undertaken. Two types of photoreactions: ring opening leading to conjugated ketene and valence isomerization to the Dewar form (1,5-dimethyl-2-oxa-3-oxobicyclo[2.2.0]hex-5-ene; DOOBH), occurred upon UV (λ>315 nm) irradiation. The latter reaction was efficient, whereas aldehyd...
Spectroscopic characterization of α- and γ-pyrones and their substituted 4-hydr...
Melo, J. Seixas de; Pina, G. Quinteiro, J.; Breda, S.; Fausto, R.The simple α- and γ-pyrones and the substituted 6-methyl, 4-hydroxy and 4-methoxy α-pyrones were investigated in relation to their spectroscopic properties. The characterization involves vibrational and electronic spectroscopy. IR spectra for the ground electronic state of the studied compounds at room temperature were obtained and interpreted taking into consideration the simulated ab initio (6-31G∗) data. The...
| Financiadores do RCAAP | |||||||
|
|
|
|
|
|
||