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Photophysical properties of closely-coupled, binuclear ruthenium(II) bis(2,2′:6′,2′-terpyridine) complexes

Lookup NU author(s): Professor Andrew Benniston, Emeritus Professor Anthony Harriman

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Abstract

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.


Publication metadata

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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