title: Interference of Interchromophoric Energy-Transfer Pathways in π-Conjugated Macrocycles.
abstract: The interchromophoric energy-transfer pathways between weakly coupled units in a π-conjugated phenylene-ethynylene macrocycle and its half-ring analogue have been investigated using the nonadiabatic excited-state molecular dynamics approach. To track the flow of electronic transition density between macrocycle units, we formulate a transition density flux analysis adapted from the statistical minimum flow method previously developed to investigate vibrational energy flow. Following photoexcitation, transition density is primarily delocalized on two chromophore units and the system undergoes ultrafast energy transfer, creating a localized excited state on a single unit. In the macrocycle, distinct chromophore units donate transition density to a single acceptor unit but do not interchange transition density among each other. We find that energy transfer in the macrocycle is slower than in the corresponding half ring because of the presence of multiple interfering energy-transfer pathways. Simulation results are validated by modeling the fluorescence anisotropy decay.
authors.affiliation: Universidad Nacional de Quilmes/CONICET, Roque Saenz Peña 352, B1876BXD Bernal, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: Alfonso Hernandez
authors.affiliation: Theoretical Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Tammie
authors.initials: T
authors.lastname: Nelson
authors.affiliation: Department of Chemistry, Technische Universität München , D-85747 Garching, Germany.
authors.forename: Maxim F
authors.initials: MF
authors.lastname: Gelin
authors.affiliation: Institut für Angewandte und Experimentelle Physik, Universität Regensburg , Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: John M
authors.initials: JM
authors.lastname: Lupton
authors.affiliation: Theoretical Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Sergei
authors.initials: S
authors.lastname: Tretiak
authors.affiliation: Universidad Nacional de Quilmes/CONICET, Roque Saenz Peña 352, B1876BXD Bernal, Argentina.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fernandez-Alberti