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Termodynamika cykloprzyłączenia nitroetylenu do Z-C-fenylo-N-arylonitronów w świetle obliczeń AM1 i AM1/COSMO

100%

Jasiński R. , Mikulska M. , Celej K. , Barański A.

2007

tom R. 104, z. 1-Ch

33-36

Zbadano termodynamikę cykloaddycji nitroetylenu do Z-C-fenylo-N-arylonitronów. Ustalono, że czynniki termodynamiczne sprzyjają powstawaniu [2+3] cykloadduktów w niskich temperaturach i mało polarnym środowisku.

The thermodynamics of nitroethene cycloaddition to Z-C-phenyl-N-arylnitrones have been studied. It has been found, that the thermodynamics parameters preffere the formation of [2+3] cycloadducts at low temperature and low polar solvents.

Change of Prototropic Equilibria for Uracil when Going from Neutral Molecule to Charged Radicals. Quantum-Chemical Studies in the Gas Phase

85%

Raczyńska E. D. , Zientara K. , Kolczyńska K. , Stępniewski T. M.

2009

tom Vol. 83, nr 5

821-834

To understand various substitution, oxidation or degradation reactions for uracil, quantum-chem i calcalculations were performed for two classes of charged radicals (cations and anions) of uracil (U+ź and U-ź) and model compounds: phenol (P+ź and P-ź) and hydroxyazines (HP1-4+ź and HP1+-4-ź). In calculations, all possible eighteen prototropic tautomers-rotamers of U and all possible five prototropic tautomers-rotamers of P and HP1-4 were considered. Stabilities, internal effects and aromatic character, estimated for charged radicals, were compared with those observed previously for neutral molecules. The great est changes of the tautomeric preferences take place for radical anions. One-electron reduction stabilizes the keto and amide functions in studied compounds, whereas one-electron oxidation favors the enol function for ph nol and the amide function for uracil and hydroxyazines.

Density functional studies of the dipole polarizabilities of the linear polyacenes benzene through nonacene

71%

Hinchliffe A. , Nikolaidi B. , Soscún Machado H.

Open Chemistry

2005

tom 3

nr 2

361-369

We report Ab Initio studies of the electric dipole polarizability of the linear polyacene series benzene through nonacene. A number of Ab Initio studies were done at different levels of theory for benzene, with all remaining Ab Initio calculations being at the B3LYP/6-311G(2d, 1p)//B3LYP/6-311+G(2d, 1p) level of theory. We find that the NN tensor component shows a constant increment of 20 atomic units per ring. AM1 and QSAR-quality empirical calculations show poor absolute agreement with the Ab Initio results but given excellent statistical correlation coefficients with the Ab Initio values. This implies that the results of such cheaper calculations can be suitably scaled for predictive purposes.