Intramolecular Vibrational Energy Redistribution in 2-Thiocytosine: SH Rotamerization Induced by Near-IR Selective Excitation of NH2 Stretching Overtone.
Near-IR-induced transformations, converting one amino-thiol conformer of 2-thiocytosine into another, were observed for monomers of the compound isolated in Ne, Ar, and N2 low-temperature matrixes. The two conformers involved in this phototransformation differ from each other by 180° rotation of the SH group. To induce the conversion, conformers of 2-thiocytosine were selectively excited to the overtone (or combination) NH2 stretching vibrational states, using very narrowband (fwhm <1 MHz) near-IR light generated in a tunable diode laser. The conformational changes were monitored by IR spectroscopy. The conformational transformation observed in the current work provides a clear evidence of the vibrational energy redistribution from the initially excited NH2 moiety to the remote SH group that changes its orientation.
Institute of Physics, Polish Academy of Sciences , Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
Anna
A
Halasa
Institute of Physics, Polish Academy of Sciences , Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
Leszek
L
Lapinski
Institute of Physics, Polish Academy of Sciences , Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
Hanna
H
Rostkowska
Institute of Physics, Polish Academy of Sciences , Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
Maciej J
MJ
Nowak