Browse by author
Lookup NU author(s): Professor Andrew Benniston,
Full text for this publication is not currently held within this repository. Alternative links are provided below where available.
Two series of geometrically-related dyads are discussed based on the difluoroborondipyrromethene (Bodipy) unit, and incorporating covalently attached hydroquinone/quinone groups. These units are anchored directly, or via a phenylene spacer, to the Bodipy core at the meso position in one series (BD-MHQ, BD-MQ, BD-MPHQ, BD-MPQ), but for the second series the attachment site is the 2-position (BD-SHQ, BD-SQ, BD-SPHQ, BD-SPQ). The compounds show various levels of fluorescence depending on the oxidation state of the appended group and the substitution pattern. In non-polar solvents such as toluene, diethyl ether and dichlorobenzene, the S, state deactivation of the Bodipy unit in BD-SPQ and BD-MPQ is dominated by (1,3)exciplex formation, which has not been reported for Bodipy derivatives so far. In the latter molecule, the decay of the exciplex is divided between population of the Bodipy triplet state (13%-21%) and ground state reformation. This partitioning is not seen for the side-on substituted derivative, BD-SPQ, and only ground state reformation is observed following decay of the exciplex. This difference in behavior is explained by the; radical-pair inter-system-crossing mechanism, which more effectively operates in BD-MPQ because of the orthogonality of the donor-acceptor units. In the more polar solvent CH3CN all the quinone derivatives show fast formation of the charge-separated state (k(CS)) followed by slower charge recombination (k(CR)). The ratio k(CS)/k(CR) <= 80.
Author(s): Benniston AC, Copley G, Lemmetyinen H, Tkachenko NV
Publication type: Article
Publication status: Published
Print publication date: 01/06/2010
ISSN (print): 1439-4235
ISSN (electronic): 1439-7641
Publisher: Wiley - VCH Verlag GmbH & Co. KGaA
Altmetrics provided by Altmetric