A new right angle-shaped ligand, 2,2′-bis(4-pyridyl)-9,9′-spirobifluorene (L), is designed and synthesized. Treatment of L with silver(I) ions leads to linear polymeric metal-organic frameworks, [Ag(L) 2 ] + (1), that feature square subunits. Single-crystal X-ray analysis reveals that [Ag(L) 2 ] + has a one-dimensional double-stranded polymeric chain comprising square grids with cavity dimensions of ca. 8 Å × 8 Å. By π-π stacking of adjacent double-stranded chains, the structure is extended into a two-dimensional (2D) layer framework with a unique quasiaperture (dimensions of ca. 14 Å × 8 Å). Each 2D layer is inclined and mutually interpenetrated, which gives rise to the three-dimensional interlocked network structure. Compound 1‚(BF 4 )(CH 3 OH) crystallizes in the monoclinic system, space group C2/c, with chemical formula C 71 H 49 N 4 OBF 4 Ag, a ) 25.709(1) Å, b ) 14.4164(6) Å, c ) 15.6865-(7) Å, β ) 109.220(2)°, and Z ) 4.
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...Ag distances are 2.776(1) and 4.575(1) A incorporated by two L ligands and by a ClO(4)(-) bridge, respectively.
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. UV-vis and emission spectra were measured, revealing the lowest excited state for all complexes as a nominally ligand-centered (3)pipi* state mixed with certain MLCT character. Introduction of the electron-withdrawing substituents on the cyclometalated chelates or replacement of one CO ligand with phosphine at the metal center increased the MLCT contribution in the first excited state, giving a broad and featureless emission with greatly enhanced quantum yields.
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