Ultrafast and Coherent Dynamics in a Solvent Switchable "Pink Box" Perylene Diimide Dimer.

Autor: Bressan G; School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK., Penty SE; School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK., Green D; Physics, Faculty of Science, University of East Anglia, Norwich, NR4 7TJ, UK., Heisler IA; Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, 9500, Brazil., Jones GA; School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK., Barendt TA; School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK., Meech SR; School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Sep 23; Vol. 63 (39), pp. e202407242. Date of Electronic Publication: 2024 Aug 22.
DOI: 10.1002/anie.202407242
Abstrakt: Perylene diimide (PDI) dimers and higher aggregates are key components in organic molecular photonics and photovoltaic devices, supporting singlet fission and symmetry breaking charge separation. Detailed understanding of their excited states is thus important. This has proven challenging because interchromophoric coupling is a strong function of dimer architecture. Recently, a macrocyclic PDI dimer was reported in which excitonic coupling could be turned on and off simply by changing the solvent. This presents a useful case where coupling is modified without synthetic changes to tune supramolecular structure. Here we present a detailed study of solvent dependent excited state dynamics in this dimer by means of coherent multidimensional spectroscopy. Spectral analysis resolves the different coupling strengths, which are consistent with solvent dependent changes in dimer conformation. The strongly coupled conformer forms an excimer within 300 fs. The low-frequency Raman active modes recovered from two-dimensional electronic spectra reveal frequencies characteristic of exciton coupling. These are assigned to modes modulating the coupling from the corresponding DFT calculations. Further analysis reveals a time dependent frequency during excimer formation. Analysis of two-dimensional "beatmaps" reveals features in the coupled dimer which are not predicted by the displaced harmonic oscillator model and are assigned to vibronic coupling.
(© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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