Temperature Dependence of Luminescence from Cu(NN)2+ Systems in Fluid Solution. Evidence for the Participation of Two Excited States

Jon R. Kirchhoff, Roland E. Gamache, Marcus W. Blaskie, Alan A.Del Paggio, Russell K. Lengel, David R. Mcmillin

Research output: Contribution to journalArticle

211 Scopus citations

Abstract

The photophysical properties of a series of homochelated complexes of the type Cu(NN)2+ are reported where (NN) denotes a heteroaromatic ligand. For the (NN) ligands 2,9-dimethyl-l,10-phenanthroline, 2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline, and 4,4’,6,6′-tetramethyl-2,2′-bipyridine, the emission quantum yields are 2.1 × 10-4, 2.5 × 1CT4, and 0.5 × 10-4, respectively, in CH2C12 solution at 25 °C. Under these conditions the lifetimes are 90, 80, and 18 ns, respectively, for the same series of compounds. In each case the emission intensity is found to decrease as the solution temperature is lowered. This is interpreted in terms of two emitting states where the population of the upper level, which has a more favorable radiative rate constant, requires thermal energy. Detailed temperature studies of the 2,9-dimethyl-l,10-phenanthroline complex have been carried out, and the results have been analyzed by assuming that the two excited states are thermally equilibrated. We conclude that the lowest energy emitting state exhibits a radiative rate constant of ca. 103 s-1 typical of a triplet state. The other state lies some 1800 cm″1 to higher energy and exhibits a radiative rate constant of ca. 107 s-1. This state is ascribed singlet multiplicity. Tentatively, both states are assumed to derive from the lowest energy charge-transfer configuration of the complex.

Original languageEnglish (US)
Pages (from-to)2380-2384
Number of pages5
JournalInorganic Chemistry
Volume22
Issue number17
DOIs
StatePublished - Aug 1983

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Fingerprint Dive into the research topics of 'Temperature Dependence of Luminescence from Cu(NN)<sub>2</sub>+ Systems in Fluid Solution. Evidence for the Participation of Two Excited States'. Together they form a unique fingerprint.

  • Cite this

    Kirchhoff, J. R., Gamache, R. E., Blaskie, M. W., Paggio, A. A. D., Lengel, R. K., & Mcmillin, D. R. (1983). Temperature Dependence of Luminescence from Cu(NN)2+ Systems in Fluid Solution. Evidence for the Participation of Two Excited States. Inorganic Chemistry, 22(17), 2380-2384. https://doi.org/10.1021/ic00159a008