title: Electron-Transfer Dynamics for a Donor-Bridge-Acceptor Complex in Ionic Liquids.
abstract: Intramolecular photoinduced electron transfer from an N,N-dimethyl-p-phenylenediamine donor bridged by a diproline spacer to a coumarin 343 acceptor was studied using time-resolved fluorescence measurements in three ionic liquids and in acetonitrile. The three ionic liquids have the bis[(trifluoromethyl)sulfonyl]amide anion paired with the tributylmethylammonium, 1-butyl-1-methylpyrrolidinium, and 1-decyl-1-methylpyrrolidinium cations. The dynamics in the two-proline donor-bridge-acceptor complex are compared to those observed for the same donor and acceptor connected by a single proline bridge, studied previously by Lee et al. (J. Phys. Chem. C 2012, 116, 5197). The increased conformational freedom afforded by the second bridging proline resulted in multiple energetically accessible conformations. The multiple conformations have significant variations in donor-acceptor electronic coupling, leading to dynamics that include both adiabatic and nonadiabatic contributions. In common with the single-proline bridged complex, the intramolecular electron transfer in the two-proline system was found to be in the Marcus inverted regime.
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , Piscataway, New Jersey 08854, United States.
authors.forename: Jessalyn A
authors.initials: JA
authors.lastname: DeVine
authors.affiliation: Department of Natural Science, Fordham University , New York, New York 10023, United States.
authors.forename: Marena
authors.initials: M
authors.lastname: Labib
authors.affiliation: Department of Natural Science, Fordham University , New York, New York 10023, United States.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Harries
authors.affiliation: Department of Natural Science, Fordham University , New York, New York 10023, United States.
authors.forename: Rouba Abdel Malak
authors.initials: RA
authors.lastname: Rached
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , Piscataway, New Jersey 08854, United States.
authors.forename: Joseph
authors.initials: J
authors.lastname: Issa
authors.affiliation: Department of Chemistry, Brookhaven National Laboratory , Upton, New York 11973-5000, United States.
authors.forename: James F
authors.initials: JF
authors.lastname: Wishart
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , Piscataway, New Jersey 08854, United States.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Castner
mesh_terms: D004563:Electrochemistry; D004579:Electron Transport; D004583:Electrons; D005453:Fluorescence; D052578:Ionic Liquids / Q000737:chemistry*; D008027:Light; D015394:Molecular Structure; D011392:Proline / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D052578:Ionic Liquids; D011392:Proline