title: Initial excited-state structural dynamics of 5,6-dimethyluracil from resonance Raman spectroscopy.
abstract: In order to understand the effect of methyl substitution patterns on the initial excited-state structural dynamics of uracil derivatives, we measured the resonance Raman spectra of 5,6-dimethyluracil (5,6-DMU). The results show that the resonance Raman spectrum is a combination of that of 5-methyl- and 6-methyluracil. The resonance Raman excitation profiles (RREPs) and absorption spectrum are simulated with a self-consistent, time-dependent formalism to yield the excited-state slopes and broadening parameters. The initial excited-state structural dynamics occur primarily along the C5═C6 stretching mode, as expected, but with lesser excited-state slopes along each mode compared to 5-methyluracil and 6-methyluracil. This study along with previous experiments with different uracil derivatives show that the presence and positions of the methyl groups seems to determine the partitioning of initial excited-state structural dynamics.
authors.affiliation: Department of Chemistry, University of Alberta , Edmonton, Alberta, Canada T6G 2G2.
authors.forename: Swaroop
authors.initials: S
authors.lastname: Sasidharanpillai
authors.forename: Glen R
authors.initials: GR
authors.lastname: Loppnow
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D013059:Spectrum Analysis, Raman; D013941:Thymine / Q000737:chemistry*; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry; D014732:Vibration
chemical_list: D000276:Adjuvants, Immunologic; D014498:Uracil; C008378:6-methyluracil; D013941:Thymine