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Positive Identification of UV-Generated, Non-Hydrogen-Bonded Isomers of o-Hydro...
Lapinski, Leszek; Rostkowska, Hanna; Reva, Igor; Fausto, Rui; Nowak, Maciej J.Non-hydrogen-bonded isomers were photogenerated by UV (λ > 335 nm) irradiation of o-hydroxybenzaldehyde (salicylaldehyde) and o-hydroxyacetophenone monomers isolated in low-temperature Ar matrixes. These photoisomerizations were found to be photoreversible. Upon shorter wavelength (λ > 235 nm or λ > 270 nm) UV irradiation, the initial forms of the compounds (with intramolecular hydrogen bonds) were partially re...
NIR-laser-induced selective rotamerization of hydroxy conformers of cytosine
Lapinski, Leszek; Nowak, Maciej J.; Reva, Igor; Rostkowska, Hanna; Fausto, RuiThe relative populations of two amino-hydroxy conformers of cytosine, differing in rotation of the OH group by 180°, were selectively and repeatedly manipulated with narrowband, near-infrared laser light. For cytosine monomers isolated in a low-temperature Ar matrix, laser irradiations at 7013 cm−1 and at 7034 cm−1 were found to induce effective transformations of the two conformers into each other.
Double-Proton-Transfer Processes in Dithiooxamide: UV-Induced Dithione → Dithi...
Lapinski, Leszek; Rostkowska, Hanna; Khvorostov, Artem; Yaman, Müjgan; Fausto, Rui; Nowak, Maciej J.Dithiooxamide [rubeanic acid, NH2C(S)C(S)NH2)] monomers were studied by FTIR spectroscopy combined with the low-temperature matrix-isolation technique. The most stable dithione−diamino tautomer of the compound was exclusively observed in argon matrixes immediately after deposition. Upon UV (λ > 345 nm) irradiation the dithione−diamino form transformed, by a double-proton transfer, into the dithiol−diimino tauto...
Photochemical Ring-Opening Reaction in 2(1H)-Pyrimidinones: A Matrix Isolation...
Lapinski, Leszek; Rostkowska, Hanna; Khvorostov, Artem; Fausto, Rui; Nowak, Maciej J.Photoreactions induced by UV-B (290−320 nm) irradiation were studied for 1-methyl-2(1H)-pyrimidinone and 1-methylcytosine monomers isolated in low-temperature inert gas matrixes. A Norrish type I α-cleavage reaction leading to open-ring conjugated isocyanate was observed for 1-methyl-2(1H)-pyrimidinone. The structure of the photoproduct was identified by comparison of its experimental IR spectrum with the spect...
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