Circularly Polarized Light Probes Excited-State Delocalization in Rectangular Ladder-type Pentaphenyl Helices.

Autor:	Ammenhäuser R; Department of Chemistry, Macromolecular Chemistry group (BUWmakro), and Wuppertal Institute for Smart Materials and Systems (CM@S), Bergische Universität Wuppertal, Gauss-Str. 20, 42119, Wuppertal, Germany., Klein P; Department of Chemistry, Macromolecular Chemistry group (BUWmakro), and Wuppertal Institute for Smart Materials and Systems (CM@S), Bergische Universität Wuppertal, Gauss-Str. 20, 42119, Wuppertal, Germany., Schmid E; Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany., Streicher S; Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany., Vogelsang J; Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany., Lehmann CW; Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany., Lupton JM; Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany., Meskers SCJ; Molecular Materials and Nanosystems and Institute of Complex Molecular Systems, Technische Universiteit Eindhoven, PO Box 513, 5600 MB, Eindhoven, The Netherlands., Scherf U; Department of Chemistry, Macromolecular Chemistry group (BUWmakro), and Wuppertal Institute for Smart Materials and Systems (CM@S), Bergische Universität Wuppertal, Gauss-Str. 20, 42119, Wuppertal, Germany.
Jazyk:	angličtina
Zdroj:	Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2023 Jan 09; Vol. 62 (2), pp. e202211946. Date of Electronic Publication: 2022 Dec 02.
DOI:	10.1002/anie.202211946
Abstrakt:	Ladder-type pentaphenyl chromophores have a rigid, planar π-system and show bright fluorescence featuring pronounced vibrational structure. Such moieties are ideal for studying interchromophoric interactions and delocalization of electronic excitations. We report the synthesis of helical polymers with a rigid square structure based on spiro-linked ladder-type pentaphenyl units. The variation of circular dichroism with increasing chain length provides direct evidence for delocalization of electronic excitations over at least 10 monomeric units. The change in the degree of circular polarization of the fluorescence across the vibronic side bands shows that vibrational motion can localize the excitation dynamically to almost one single unit through breakdown of the Born-Oppenheimer approximation. The dynamic conversion between delocalized and localized excited states provides a new paradigm for interpreting circular dichroism in helical polymers such as proteins and polynucleic acids. (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze:	MEDLINE
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