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Title: | Molecular Structure, Vibrational Spectra, Quantum Chemical Calculations and Photochemistry of Picolinamide and Isonicotinamide Isolated in Cryogenic Inert Matrixes and in the Neat Low-Temperature Solid Phases | Authors: | Borba, Ana Gómez-Zavaglia, Andrea Fausto, R. |
Issue Date: | Dec-2007 | Publisher: | American Chemical Society | Serial title, monograph or event: | J. Phys. Chem. A, | Volume: | 112 | Abstract: | 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 cryogenic rare gas matrixes. Comparison between the experimental spectra of the matrix-isolated compounds with those theoretically predicted allowed for full assignment of the experimental spectra. In situ UV (λ > 235 nm) irradiation of the matrixes showed that only PA reacts, with production of isocyanic acid and pyridine, the first photoproduct further reacting to yield CO + NH and cyanic acid. The different photochemical behavior of the two compounds was explained taking into consideration their different structures. The infrared spectra of (i) the low-temperature glassy state resulting from fast deposition of vapors of the compounds onto a substrate cooled to 10 K, (ii) the crystal resulting from the annealed amorphous film of the compound, and (iii) the room-temperature crystals (α-phase) of the studied compounds were also obtained, fully assigned and correlated with intermolecular interactions present in the condensed phases, in particular H-bond interactions, showing that these latter are stronger in INA than in PA. | URI: | https://hdl.handle.net/10316/17942 | DOI: | 10.1021/jp0765547 | Rights: | openAccess |
Appears in Collections: | FCTUC Química - Artigos em Revistas Internacionais |
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J.Physical Chemistry A , 112 (2008) 45.pdf | 312.64 kB | Adobe PDF | View/Open |
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