Control of triplet state generation in heavy atom-free BODIPY-anthracene dyads by media polarity and structural factors

Mikhail A. Filatov*, Safakath Karuthedath, Pavel M. Polestshuk, Susan Callaghan, Keith J. Flanagan, Maxime Telitchko, Thomas Wiesner, Frédéric Laquai, Mathias O. Senge

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

85 Scopus citations

Abstract

A family of heavy atom-free BODIPY-anthracene dyads (BADs) exhibiting triplet excited state formation from charge-transfer states is reported. Four types of BODIPY scaffolds, different in the alkyl substitution pattern, and four anthracene derivatives have been used to access BADs. Fluorescence and intersystem crossing (ISC) in these dyads depend on donor-acceptor couplings and can be accurately controlled by substitution or media polarity. Under conditions that do not allow charge transfer (CT), the dyads exhibit fluorescence with high quantum yields. Formation of charge-transfer states triggers ISC and the formation of long-lived triplet excited states in the dyads. The excited state properties were studied by steady-state techniques and ultrafast pump-probe spectroscopy to determine the parameters of the observed processes. Structural information for various BADs was derived from single crystal X-ray structure determinations alongside DFT molecular geometry optimization, revealing the effects of mutual orientation of subunits on the photophysical properties. The calculations showed that alkyl substituents on the BODIPY destabilize CT states in the dyads, thus controlling the charge transfer between the subunits. The effect of the dyad structure on the ISC efficiency was considered at the M06-2X level of theory, and a correlation between mutual orientation of the subunits and the energy gap between singlet and triplet CT states was studied using a multireference CASSCF method.

Original languageEnglish (US)
Pages (from-to)8016-8031
Number of pages16
JournalPhysical Chemistry Chemical Physics
Volume20
Issue number12
DOIs
StatePublished - 2018

Bibliographical note

Funding Information:
This work was supported by grants from the European Commission (CONSORT, Grant No. 655142), Science Foundation Ireland (SFI IvP 13/IA/1894) and the Irish Research Council (GOIPG/2016/1250). The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST).

Publisher Copyright:
© 2018 the Owner Societies.

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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