Luminescence studies of pyridine. alpha. -diimine rhenium(I) tricarbonyl complexes

Journal Article · Wed Oct 17 04:00:00 EDT 1990 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00346a033· OSTI ID:6119809

Sacksteder, L; Brown, E A; Demas, J N ^[1]; Zipp, A P; Streich, J ^[2]; DeGraff, B A ^[3]

---

1. Univ. of Virginia, Charlottesville (USA)
2. State Univ. of New York, Cortland (USA)
3. James Madison Univ., Harrisonburg, VA (USA)

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. 25 refs., 6 figs., 2 tabs.

• OSTI ID: 6119809
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:21; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
AROMATICS
AZAARENES
AZINES
CARBONYLS
COMPLEXES
CONVERSION
ENERGY CONVERSION
HETEROCYCLIC COMPOUNDS
LUMINESCENCE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHENANTHROLINES
PHOTOSENSITIVITY
PYRIDINES
RHENIUM COMPLEXES
SENSITIVITY
SOLAR ENERGY CONVERSION
TRANSITION ELEMENT COMPLEXES