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

 
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2007 (EN)
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 (EN)

Lazarides, T. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Lazarides, T. (EN)

We show in this paper how the (MLCT)-M-3 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 Ba2+) 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((t)Bu(2)bipy)(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 (MLCT)-M-1 absorptions, and (MLCT)-M-3 energies, intensities, and lifetimes, with the complex varying from essentially non-luminescent in the absence of metal cation to showing strong (phi = 0.07), long-lived (1.4 mu s), and high-energy (583 nm) luminescence in the presence of Ba2+. This modulation of the (MLCT)-M-3 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 (MLCT)-M-3 energy and thereby quenches the [Ru(bipy)(3)](2+)-based luminescence; in the presence of Ba2+ ions, the (MLCT)-M-3 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. (EN)

near-infrared luminescence (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

J Am Chem Soc (EN)

English

2007

<Go to ISI>://000245241600054

American Chemical Society (EN)



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