title: Intermolecular interactions and aggregation of fac-tris(2-phenylpyridinato-C2,N)iridium(III) in nonpolar solvents.
abstract: The intermolecular interaction and aggregation of the neutral complex fac-tris(2-phenylpyridinato-C(2),N)iridium(III) (fac-Ir(ppy)3) in solution was investigated. Intermolecular interactions were found to effectively decrease the luminescence lifetime via self-quenching with increasing fac-Ir(ppy)3 concentrations. A Stern-Volmer plot for quenching in acetonitrile was linear, due to bimolecular self-quenching, but curved in toluene as the result of excimer formation. (1)H NMR spectra demonstrated a monomer-aggregate equilibrium which resulted in spectral shifts depending on solvent polarity. X-ray crystallography provided structural information concerning the aggregate, which is based on a tetramer consisting of two Δ-fac-Ir(ppy)3-Λ-fac-Ir(ppy)3 pairs. Offset π-π stacking of ppy ligands and electrostatic dipole-dipole interactions between complex molecules play an important role in the formation of these molecular pairs.
authors.affiliation: Department of Nanosystem Science, Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takayasu
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Kazuteru
authors.initials: K
authors.lastname: Shinozaki
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D056831:Coordination Complexes; D009942:Organometallic Compounds; D012997:Solvents; C587288:fac-tris(2-phenylpyridinato-C2,N)iridium(III); C520414:tris(2-phenylpyridine)iridium(III); D001554:Benzene; C032159:acetonitrile