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Lookup NU author(s): Professor Andrew Benniston, Emeritus Professor Anthony Harriman
The photophysical properties of closely-coupled, binuclear complexes formed by connecting two ruthenium(II) bis(2,2′:6′,2″-terpyridine) complexes via an alkynylene group are compared to those of the parent complex. The dimers exhibit red-shifted emission maxima and prolonged triplet lifetimes in deoxygenated solution. Triplet quantum yields are much less than unity and the dimers generate singlet molecular oxygen with low quantum efficiency. Temperature dependence emission studies indicate coupling to higher-energy triplet states while cyclic voltammetry shows that the metal centres are only very weakly coupled but that extensive electron delocalisation occurs upon one-electron reduction. The radiative rate constants derived for these dimers are relatively low, because the lowest-energy metal-to-ligand, charge-transfer states possess increased triplet character. In contrast, the rate constants for nonradiative decay of the lowest-energy triplet states are kept low by extended electron delocalisation over the polytopic ligand. The poor triplet yields are a consequence of partitioning at the second triplet level.
Author(s): Benniston AC, Grosshenny V, Harriman A, Ziessel R
Publication type: Article
Publication status: Published
Journal: Dalton Transactions
Year: 2004
Issue: 8
Pages: 1227-1232
Date deposited: 09/07/2010
ISSN (print): 1477-9226
ISSN (electronic): 1477-9234
Publisher: Royal Society of Chemistry
URL: http://dx.doi.org/10.1039/b400931b
DOI: 10.1039/b400931b
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