title: Molecular Polygons Probe the Role of Intramolecular Strain in the Photophysics of π-Conjugated Chromophores.
abstract: π-Conjugated segments, chromophores, are the electronically active units of polymer materials used in organic electronics. To elucidate the effect of the bending of these linear moieties on elementary electronic properties, such as luminescence color and radiative rate, we introduce a series of molecular polygons. The π-system in these molecules becomes so distorted in bichromophores (digons) that these absorb and emit light of arbitrary polarization: any part of the chain absorbs and emits radiation with equal probability. Bending leads to a cancellation of transition dipole moment (TDM), increasing excited-state lifetime. Simultaneously, fluorescence shifts to the red as radiative transitions require mixing of the excited state with vibrational modes. However, strain can become so large that excited-state localization on shorter units of the chain occurs, compensating TDM cancellation. The underlying correlations between shape and photophysics can only be resolved in single molecules.
authors.affiliation: Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Wilhelm
authors.affiliation: Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Vogelsang
authors.affiliation: Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany.
authors.forename: Georgiy
authors.initials: G
authors.lastname: Poluektov
authors.affiliation: Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Schönfelder
authors.affiliation: Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany.
authors.forename: Tristan J
authors.initials: TJ
authors.lastname: Keller
authors.affiliation: Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany.
authors.forename: Stefan-Sven
authors.initials: SS
authors.lastname: Jester
authors.affiliation: Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany.
authors.forename: Sigurd
authors.initials: S
authors.lastname: Höger
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
keywords: intramolecular strain; macrocycles; organic electronics; single-molecule spectroscopy