Luminescent osmium(II) complexes with functionalized 2-phenylpyridine chelating ligands: preparation, structural analyses, and photophysical properties.

Cyclometalated osmium complexes with the formulas [Os(ppy) 2(CO) 2] ( 1a, b), [Os(dfppy) 2(CO) 2] ( 2a, b), and [Os(btfppy) 2(CO) 2] ( 3a, b) have been synthesized, for which the chelating chromophores ppyH, dfppyH, and btfppyH denote 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, and 2-(2,4-bis(trifluoromethyl)phenyl)pyridine, respectively. The isomers 1a- 3a, possessing an intrinsic C 2 rotational axis as determined by single-crystal X-ray diffraction analysis, underwent slow isomerization in solution at elevated temperature, giving the respective thermodynamic products 1b- 3b, which showed a distinctive coordination arrangement produced by a 180 degrees rotation of one cyclometalated ligand around the Os(II) metal center. In contrast to the case for 1a, b and 2a, which are inert to substitution, complexes 2b and 3b (or 3a) readily react with PPh 2Me to afford the products [Os(dfppy) 2(CO)(PPh 2Me)] ( 4) and [Os(btfppy) 2)(PPh 2Me)] ( 6), in which the incoming PPh 2Me replaced the CO located trans to the carbon atom of one cyclometalated ligand.

Strategic design and synthesis of osmium(II) complexes bearing a single pyridyl azolate pi-chromophore: achieving high-efficiency blue phosphorescence by localized excitation.

We present the strategic design and synthesis of Os(II) complexes bearing a single pyridyl azolate pi-chromophore with an aim to attain high efficiency blue phosphorescence by way of localized transition. It turns out that our proposal of localized excitation seems to work well upon anchoring a single pi-chromophore on the Os(II) complexes such that the control of MLCT versus pipi* (or even LLCT) transitions is more straightforward. Among the titled complexes, [Os(CO)3(tfa)(fppz)] (1) and [Os(CO)3(tfa)(fbtz)] (5) (tfa=trifluoroacetate, (fppz)H=3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, and (fbtz)H=3-(trifluoromethyl)-5-(4-tert-butyl-2-pyridyl)-1,2,4-triazole) give the anticipated blue phosphorescence with efficiencies of 0.

Structural characterization and luminescence behavior of a silver(I) 1D polymeric chain constructed via a Bridge with unusual 4,5-diazospirobifluorene and perchlorate.

A new polymeric silver complex, [Ag(2)(L(2))(ClO(4))(2)] (L = 4,5-diazospirobifluorene), has been synthesized and shown to exhibit interesting luminescence properties in a single crystal. Structural analysis reveals a one-dimensional chain, which contains a [Ag(2)(L(2))](2+) dimer bridged with ClO(4)(-). The Ag.