Intramolecular excited-state interactions of surfactant-active osmium(II) photosensitizers

• Published in: Inorganic chemistry 1989-05, Vol.28 (10), p.1787-1792
• Main Authors: Sacksteder, Lou Ann, Demas, J. N, DeGraff, B. A
• Format: Article
• Language: English
• Subjects: 400500 - Photochemistry; AROMATICS; AZAARENES; AZINES; CHEMICAL PREPARATION; Chemistry; COMPLEXES; DATA; ENERGY LEVELS; Exact sciences and technology; EXCITED STATES; EXPERIMENTAL DATA; General and physical chemistry; HETEROCYCLIC COMPOUNDS; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OSMIUM COMPLEXES; PHENANTHROLINES; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); PYRIDINES; SYNTHESIS; TRANSITION ELEMENT COMPLEXES
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic00309a007

A new class of luminescent surfactant-active complexes, cis-OsL{sub 2}(CO)NC(CH{sub 2}){sub n}CH{sub 3}{sup 2+} (n = 0-19; L = 2,2{prime}-bipyridine and 1,10-phenanthroline), were synthesized and characterized. They represent another example of an intramolecular perturbation of excited-state properties by what would normally be considered an electronically passive alkyl ligand. The effect is smaller in the Os(II) case and has a different n dependence than was observed in the fac-ReL(CO){sub 3}NC(CH{sub 2}){sub n}CH{sub 3}{sup +} system. The differences arise from varied geometric constraints on the foldback and the orbital parentage of the emitting state. Foldback must be directly to ligands involved in the emission process in order to perturb the emission. The osmium(II) center highly activates the bound nitrile to thermal nucleophilic attack, and luminescent adducts are formed with alcohols and aliphatic and aromatic amines. Such activation has not been previously observed in complexes with {alpha}-diimine ligands. The complexes also photodecompose by labilization of the nitrile. 37 refs., 5 figs.