Characterization of the triplet state of tris(8-hydroxyquinoline)aluminium(III) in benzene solution

Hugh D Burrows; Mariana Fernandes; J Seixas de Melo; Andrew P Monkman; Suppiah Navaratnam

doi:10.1021/ja037254f

Characterization of the triplet state of tris(8-hydroxyquinoline)aluminium(III) in benzene solution

J Am Chem Soc. 2003 Dec 17;125(50):15310-1. doi: 10.1021/ja037254f.

Authors

Hugh D Burrows¹, Mariana Fernandes, J Seixas de Melo, Andrew P Monkman, Suppiah Navaratnam

Affiliation

¹ Departamento de Química, Universidade de Coimbra, P3004-535 Coimbra, Portugal. burrows@ci.uc.pt

PMID: 14664573
DOI: 10.1021/ja037254f

Abstract

The lowest triplet state of tris(8-hydroxyquinoline)aluminium(III) (Alq3) has been prepared by pulse radiolysis/energy transfer from appropriate donors in benzene solutions and has an absorption maximum around 510 nm with a lifetime of about 50 mus. It is quenched by molecular oxygen, leading to singlet oxygen formation. From flash photolysis and singlet oxygen formation measurements, a quantum yield of triplet formation of 0.24 was determined for direct photolysis of the complex. A value of 2.10 +/- 0.10 eV was determined for the energy of the lowest triplet state by energy transfer studies and was confirmed by phosphorescence measurements on Alq3, either in the heavy atom solvent ethyl iodide or photosensitized by benzophenone in benzene. Dexter (exchange) energy transfer was observed from triplet Alq3 to platinum(II) octaethylporphyrin.