title: Singlet excited-state interactions in naphthalene-thymine dyads.
abstract: Two thymidine-derived nucleosides 1 and 2 were prepared by attaching a chiral naphthalene to the positions 5' and 3' of the sugar. The resulting dyads, which contain key substructures present in drugs and nucleic acids, exhibit different spatial arrangements (transoid or cisoid) of the fluorophore relative to the thymine unit. Emission measurements on these compounds in the presence of ROH molecules revealed a remarkable intramolecular prescence quenching for dyad 1. The obtained results are consistent with quenching of the singlet excited state of 1 by hydrogen-bond donor solvents. Thus, a physical deactivation process (vibronically induced internal conversion) would be the pathway responsible for the accelerated decay of 1*, favorably competing with fluorescence and intersystem crossing to the triplet. This effect appears to be strongly dependent on the relative spatial arrangement between the naphthalene and thymine units, together with the hydrogen-bonding ability of the employed ROH.
authors.affiliation: Instituto de Tecnología Química UPV-CSlC/Departamento de Química, Universidad Politécnica de Valencia, Avda de los Naranjos s/n, 46022 Valencia, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Encinas
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Climent
authors.forename: Salvador
authors.initials: S
authors.lastname: Gil
authors.forename: Urban O
authors.initials: UO
authors.lastname: Abrahamsson
authors.forename: Jan
authors.initials: J
authors.lastname: Davidsson
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Miranda
mesh_terms: D018360:Crystallography, X-Ray; D007834:Lasers; D008958:Models, Molecular; D008968:Molecular Conformation; D009281:Naphthalenes / Q000737:chemistry*; D010782:Photolysis; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013941:Thymine / Q000737:chemistry*
chemical_list: D009281:Naphthalenes; C031721:naphthalene; D013941:Thymine