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Luminescence Studies of Pyridine α-Diimine Rhenium(I) Tricarbonyl Complexes
Inorganic Chemistry (1990)
  • L. Sacksteder
  • A. P. Zipp
  • Elizabeth Brown, Binghamton University--SUNY
  • J. Streich
  • J. N. Demas
  • B. A. DeGraff
The room- and low-temperature luminescences of ReL(CO){sub 3}X where L = 2,2{prime}-bipyridine, 1,10-phenanthroline, or 5-phenyl-1,10-phenanthroline and X = substituted pyridine or quinoline were studied. Relatively small but useful variations in the state energies can be effected by altering the Hammett {sigma} values of substituents on the pyridines. All complexes exhibit metal to ligand charge-transfer (MLCT) phosphorescences at room temperature. However, by choice of suitable ligands, the emissions can be switched to ligand-localized phosphoresecence on cooling to 77 K. This behavior is explained on the basis of the proximity of the lowest MLCT and {pi}-{pi}{sup *} triplet states and the changes in energy of the MLCT state as a function of temperature. At room temperature the MLCT state can equilibrate to an energy that is lower than that of {sup 3}{pi}-{pi}{sup *} state and give MLCT luminescence. In rigid low-temperature media, however, the MLCT state cannot relax during the excited-state decay and emission is from the lower energy {sup 3}{pi}-{pi}{sup *} state. At room temperature, lifetimes are predominantly affected by alterations in the nonradiative rate constant, as described by the energy-gap law. From {sigma} values of the substituents, both state energies and lifetimes can be predicted before synthesis. The design of new luminescent complexes is discussed.
  • solar energy,
  • Photobiological,
  • & Thermochemical Conversion
Publication Date
Citation Information
L. Sacksteder, A. P. Zipp, Elizabeth Brown, J. Streich, et al.. "Luminescence Studies of Pyridine α-Diimine Rhenium(I) Tricarbonyl Complexes" Inorganic Chemistry Vol. 29 (1990) p. 4335 - 4340
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