title: Theoretical study of electronic spectra and photophysics of uracil derivatives.
abstract: The changes that the UV absorption spectrum and the photophysics of uracil undergo under hydrogen substitution or deprotonation, were studied theoretically within the CS-INDO/CI scheme. First of all this method was tested on uracil. It was then used for the calculation of the electronic structure of excited states (Sn, Tn) of a large number of uracil derivatives (1-, 3- and 5-methyluracil; 1,3-, 1,5- and 3,5-dimethyluracil; 5-fluoro- and 5-chlorouracil), including some anions (1- and 3-methyluracil anion). The excited states were obtained in the singly-excited configuration interaction approximation (S-CI) and the correlation effects on (pi pi*) states were studied by including the most important doubly- and triply-excited configurations in the CI. The S-CI wavefunctions were used for the calculation of the most important electronic matrix elements for spin-orbit coupling. The photophysics of these compounds is discussed using Jablonski diagrams.
authors.affiliation: Dipartimento di Chimica, Università di Modena, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Baraldi
authors.forename: M C
authors.initials: MC
authors.lastname: Bruni
authors.forename: M P
authors.initials: MP
authors.lastname: Costi
authors.forename: P
authors.initials: P
authors.lastname: Pecorari
mesh_terms: D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D015394:Molecular Structure; D010777:Photochemistry; D013056:Spectrophotometry, Ultraviolet; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry*
chemical_list: D014498:Uracil