Excited-state properties of chiral [4]helicene cations

Kel, Oksana; Sherin, Petr; Mehanna, Nathalie; Laleu, Benoît; Lacour, Jérôme; Vauthey, Eric

doi:10.1039/c2pp05361f

Scientific article

English

Excited-state properties of chiral [4]helicene cations

Contributors

Kel, Oksana; Sherin, Petr; Mehanna, Nathalie; Laleu, Benoît; Lacour, Jérôme

; Vauthey, Eric

Published in

Photochemical & photobiological sciences, vol. 11, no. 4, p. 623-631

Publication date

2012

Abstract

The photophysical properties of a series of helicene cations in various solvents have been investigated using stationary and time-resolved spectroscopy. These compounds fluoresce in the near infrared region with a quantum yield ranging between 2 and 20% and a lifetime between 1 and 12 ns, depending of the solvent. No clear solvent dependence could be recognized except for a decrease of fluorescence quantum yield and lifetime with increasing hydrogen-bond donating ability of the solvent. In water, the helicene cations undergo aggregation. This effect manifests itself by the presence of a slow fluorescence decay component, whose amplitude increases with dye concentration, and by a much slower decay of the polarization anisotropy in water compared to an organic solvent of similar viscosity. However, aggregation has essentially no effect on the stationary fluorescence spectrum, whereas relatively small changes can be seen in the absorption spectrum. Analysis of the dependence of aggregation on the dye concentration reveals that the aggregates are mostly dimers and that the aggregation constant is substantially larger for hetero- than homochiral dimers.

UNIGE affiliation entities

Citation (ISO format)

KEL, Oksana et al. Excited-state properties of chiral [4]helicene cations. In: Photochemical & photobiological sciences, 2012, vol. 11, n° 4, p. 623–631. doi: 10.1039/c2pp05361f

Article (Published version)

Identifiers

PID : unige:18976
DOI : 10.1039/c2pp05361f

Additional URL for this publication

http://xlink.rsc.org/?DOI=c2pp05361f

Journal ISSN

1474-905X

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22/03/2012 10:54:00

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Excited-state properties of chiral [4]helicene cations

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Published in

Publication date

Abstract

UNIGE affiliation entities

Citation (ISO format)

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First validation

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