Structural and photophysical properties of adducts of [Ru(bipy)(CN) 4]2- with different metal cations: Metallochromism and its use in switching photoinduced energy transfer

Theodore Lazarides, Timothy L. Easun, Claire Veyne-Martí, Wassím Z. Alsindi, Michael W. George, Nina Deppermann, Christopher A. Hunter, Harry Adams, Michael D. Ward

Research output: Journal PublicationArticlepeer-review

57 Citations (Scopus)

Abstract

We show in this paper how the 3MLCT luminescence of [Ru(bipy)(CN)4]2-, which is known to be highly solvent-dependent, may be varied over a much wider range than can be achieved by solvent effects, by interaction of the externally directed cyanide ligands with additional metal cations both in the solid state and in solution. A series of crystallographic studies of [Ru(bipy)(CN)4]2- salts with different metal cations Mn+ (Li+, Na+, K +, mixed Li+/K+, Cs+, and Ba 2+) shows how the cyanide/Mn+ interaction varies from the conventional "end-on" with the more Lewis-acidic cations (Li +, Ba2+) to the more unusual "side-on" interaction with the softer metal cations (K+, Cs+). The solid-state luminescence intensity and lifetime of these salts is highly dependent on the nature of the cation, with Cs+ affording the weakest luminescence and Ba2+ the strongest. A series of titrations of the more soluble derivative [Ru(tBu2bipy)(CN) 4]2- in MeCN with a range of metal salts showed how the cyanide/Mn+ association results in a substantial blue-shift of the 1MLCT absorptions, and 3MLCT energies, intensities, and lifetimes, with the complex varying from essentially non-luminescent in the absence of metal cation to showing strong (φ = 0.07), long-lived (1.4 μs), and high-energy (583 nm) luminescence in the presence of Ba 2+. This modulation of the 3MLCT energy, over a range of about 6000 cm-1 depending on the added cation, could be used to reverse the direction of photoinduced energy transfer in a dyad containing covalently linked [Ru(bipy)3]2+ and [Ru(bipy)(CN) 4]2- termini. In the absence of a metal cation, the [Ru(bipy)(CN)4]2- terminus has the lower 3MLCT energy and thereby quenches the [Ru(bipy)3]2+-based luminescence; in the presence of Ba2+ ions, the 3MLCT energy of the [Ru(bipy)(CN)4]2- terminus is raised above that of the [Ru(bipy)3]2+ terminus, resulting in energy transfer to and sensitized emission from the latter.

Original languageEnglish
Pages (from-to)4014-4027
Number of pages14
JournalJournal of the American Chemical Society
Volume129
Issue number13
DOIs
Publication statusPublished - 4 Apr 2007
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Biochemistry
  • Colloid and Surface Chemistry

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