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Five isomers of monomeric cytosine and their interconversions induced
Lapinski, Leszek; Igor Reva, Igor Reva; Nowak, Maciej J.; Fausto, RuiPhotoisomerization processes involving five isomers of cytosine were induced by narrowband tunable UV irradiation of matrix-isolated monomers of the compound. Irradiation of an argon matrix containing cytosine monomers with UV l = 313 nm laser light resulted in syn2anti photoisomerizations between the two imino–oxo forms, whereas the substantially more populated amino–hydroxy and amino–oxo forms stayed intact. ...
Thermal and Photoinduced Control of Relative Populations of 4-Methoxybenzaldehy...
Kus, Nihal; Sharma, Archna; Reva, Igor; Lapinski, Leszek; Fausto, RuiTwo almost isoenergetic conformers of 4-methoxybenzaldehyde (p-anisaldehyde), O-trans and O-cis, are nearly equally populated in gas phase at room temperature. The existence of these two conformers of similar energy makes p-anisaldehyde an attractive molecule for conformational investigations, in which the relative populations of the two forms might be subjected to optical control. In the present study, monomer...
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...
Infrared spectra of methyl isocyanate isolated in Ar, Xe and N2 matrices
Reva, Igor; Lapinski, Leszek; Fausto, RuiThe infrared spectra of methyl isocyanate monomer isolated in cryogenic argon, xenon and nitrogen matrices were studied. Interpretation of the experimental results was supported by harmonic and anharmonic calculations carried out at the DFT, MP2 and CCSD levels of approximation. Spectral indicators of the molecule structural flexibility were examined, the most striking of these being the multiplet structure of ...
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.
Photoinduced oxidation of triphenylphosphine isolated in a low-temperature oxyg...
Reva, Igor; Lapinski, Leszek; Nowak, Maciej J.http://www.sciencedirect.com/science/article/B6TFN-4TXF81D-3/2/a7ee21821936ceab2970c58d4ce846aa
Photoinduced transformation of matrix-isolated methyl 2-pyrone-3-carboxylate in...
Reva, Igor; Nowak, Maciej J.; Lapinski, Leszek; Fausto, RuiPhotochemical transformations of methyl 2-pyrone-3-carboxylate (mp3c) were studied by matrix-isolation technique. The dominating primary photoreaction induced by UV (λ > 295 nm) light was α-bond cleavage leading to open-ring aldehyde–ketene. Another reaction characteristic of α-pyrones, isomerisation to the Dewar form, did not occur for mp3c. The ring-opening photoreaction was followed by intramolecular hydroge...
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...
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...
Photochemical alpha-Cleavage in Pyran-2-thione: Generation of Aldehyde-Thiokete...
Breda, Susana; Reva, Igor D.; Lapinski, Leszek; Fausto, RuiNo Abstract ; http://dx.doi.org/10.1002/cphc.200400539
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