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Efficient Intramolecular Charge Transfer in Oligoyne-Linked Donor–π–Acceptor Molecules

Pålsson, L.-O.; Wang, C.; Batsanov, A.S.; King, S.M.; Beeby, A.; Monkman, A.P.; Bryce, M.R.

Efficient Intramolecular Charge Transfer in Oligoyne-Linked Donor–π–Acceptor Molecules Thumbnail


Authors

C. Wang

A.S. Batsanov

S.M. King

A. Beeby



Abstract

Studies are reported on a series of triphenylamine–(C[TRIPLE BOND]C)n–2,5-diphenyl-1,3,4-oxadiazole dyad molecules (n=1–4, 1, 2, 3 and 4, respectively) and the related triphenylamine-C6H4–(C[TRIPLE BOND]C)3–oxadiazole dyad 5. The oligoyne-linked D–π–A (D=electron donor, A=electron acceptor) dyad systems have been synthesised by palladium-catalysed cross-coupling of terminal alkynyl and butadiynyl synthons with the corresponding bromoalkynyl moieties. Cyclic voltammetric studies reveal a reduction in the HOMO–LUMO gap in the series of compounds 1–4 as the oligoyne chain length increases, which is consistent with extended conjugation through the elongated bridges. Photophysical studies provide new insights into conjugative effects in oligoyne molecular wires. In non-polar solvents the emission from these dyad systems has two different origins: a locally excited (LE) state, which is responsible for a π*[RIGHTWARDS ARROW]π fluorescence, and an intramolecular charge transfer (ICT) state, which produces charge-transfer emission. In polar solvents the LE state emission vanishes and only ICT emission is observed. This emission displays strong solvatochromism and analysis according to the Lippert–Mataga–Oshika formalism shows significant ICT for all the luminescent compounds with high efficiency even for the longer more conjugated systems. The excited-state properties of the dyads in non-polar solvents vary with the extent of conjugation. For more conjugated systems a fast non-radiative route dominates the excited-state decay and follows the Engelman–Jortner energy gap law. The data suggest that the non-radiative decay is driven by the weak coupling limit.

Citation

Pålsson, L., Wang, C., Batsanov, A., King, S., Beeby, A., Monkman, A., & Bryce, M. (2009). Efficient Intramolecular Charge Transfer in Oligoyne-Linked Donor–π–Acceptor Molecules. Chemistry - A European Journal, 16(5), 1470-1479. https://doi.org/10.1002/chem.200902099

Journal Article Type Article
Acceptance Date Jul 28, 2009
Online Publication Date Dec 18, 2009
Publication Date Dec 18, 2009
Deposit Date Feb 1, 2012
Publicly Available Date Mar 29, 2024
Journal Chemistry - A European Journal
Print ISSN 0947-6539
Electronic ISSN 1521-3765
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 16
Issue 5
Pages 1470-1479
DOI https://doi.org/10.1002/chem.200902099

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Copyright Statement
This is the peer reviewed version of the following article: Pålsson, L.-O., Wang, C., Batsanov, A.S., King, S.M., Beeby, A., Monkman, A.P. & Bryce, M.R. (2010). Efficient Intramolecular Charge Transfer in Oligoyne-Linked Donor–π–Acceptor Molecules. Chemistry - A European Journal 16(5): 1470-1479, which has been published in final form at https://doi.org/10.1002/chem.200902099. This article may be used for non-commercial purposes in accordance With Wiley-VCH Terms and Conditions for self-archiving.


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