Mononuclear and dinuclear osmium(II) compounds containing 2,2 prime -bipyridine and 3,5-bis(pyridin-2-yl)-1,2,4-triazole: Synthesis, electrochemistry, absorption spectra, and luminescence properties

Journal Article · Wed Feb 20 00:00:00 EST 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00004a010· OSTI ID:6033881

Barigelletti, F; De Cola, L ^[1]; Balzani, V ^[2]; Hage, R; Haasnoot, J G; Reedijk, J ^[3]; Vos, J G ^[4]

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1. Ist. FRAE-CNR, Bologna (Italy)
2. Inst. FRAE-CNR, Bologna (Italy) ; Univ. of Bologna (Italy)
3. Leiden Univ. (Netherlands)
4. Dublin City Univ. (Ireland)

The synthesis, structure, electrochemical behavior, absorption spectra, luminescence spectra (from 90 to 298 K), luminescence lifetimes (from 90 to 298 K), and photoreactivity of the complexes Os(bpy){sub 2}(bpt){sup +} (1) and (Os(bpy){sub 2}){sub 2}(bpt){sup 3+} (2), where by = 2,2{prime}-bipyridine and Hbpt = 3,5-bis(pyridin-2-yl)-1,2,4-triazole, are reported. The properties exhibited by 1 and 2 are compared with those of Os(bpy){sub 3}{sup 2+} and of the analogous Ru(II) complexes. For both 1 and 2, the lowest energy absorption band and the luminescence band are attributed to Os {yields} bpy metal-to-ligand charge-transfer (MLCT) singlet and triplet excited states, respectively. Electrochemical oxidation is centered on the metal(s), and electrochemical reduction is centered on the ligands, with bpy being reduced at less negative potentials than bpt{sup {minus}}. Because of the stronger {sigma}-donor ability of bpt{sup {minus}} compared with bpy, the Os {yields} bpy CT absorption and emission bands of 1 are red-shifted compared with those of the parent Os(bpy){sub 3}{sup 2+} complex. In nitrile rigid matrix at 90 K, the emission lifetimes are 250 and 340 ns for 1 and 2, respectively. For both complexes, increasing temperature causes a decrease of the emission lifetime but the ln (1/{tau}) vs 1/T plots between 90 and 298 K do not exhibit the highly activated decay processes characteristic of the {sup 3}MLCT {yields} {sup 3}MC crossover. In agreement with this result, no photodecomposition was observed in CH{sub 2}Cl{sub 2} solutions containing Cl{sup {minus}} ions.

• OSTI ID: 6033881
• Journal Information: Inorganic Chemistry; (United States), Vol. 30:4; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BIPYRIDINES
LUMINESCENCE
OSMIUM COMPOUNDS
TRIAZOLES
ABSORPTION SPECTRA
CHEMICAL PREPARATION
ELECTROCHEMISTRY
EXPERIMENTAL DATA
PHOTOCHEMISTRY
AZINES
AZOLES
CHEMISTRY
DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
REFRACTORY METAL COMPOUNDS
SPECTRA
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
400201 - Chemical & Physicochemical Properties
400500 - Photochemistry