title: Investigation of the mechanisms of photo-induced formation of cyclobutane dimers of cytosine and 2,4-diaminopyrimidine.
abstract: The mechanisms of the formation of cyclobutane dimers (CBD) of cytosine and 2,4-diaminopyrimidine were studied at the CC2 theoretical level and cc-pVDZ basis functions. Four orientations of the two monomers are explored: cys-syn, cis-anti, trans-syn, and trans-anti. The research revealed that in all cases the cyclobutane structures are formed along the (1)ππ* excited-state reaction paths of the stacked aggregates. We localized the S1/S0 conical intersections mediating those transformations. The results obtained agree well with the previously reported investigations on the cis-syn cyclodimer formations of other pyrimidines.
authors: Physical Chemistry, University of Plovdiv, Plovdiv, 4000, Bulgaria.
authors: Pavlina B
authors: PB
authors: Kancheva
authors: Physical Chemistry, University of Plovdiv, Plovdiv, 4000, Bulgaria. vdelchev@uni-plovdiv.net.
authors: Vassil B
authors: VB
authors: Delchev
mesh_terms: D003596:Cytosine / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D010777:Photochemistry; D011740:Pyrimidine Dimers / Q000138:chemical synthesis*; D011743:Pyrimidines / Q000737:chemistry*
chemical_list: D011740:Pyrimidine Dimers; D011743:Pyrimidines; C017205:2,4-diaminopyrimidine; D003596:Cytosine
keywords: Ab initio calculations; Cyclobutane photodimers; Excited states; Nucleic acid bases; Photo-induced cyclodimerization