Practical and Convenient Synthesis of 1,6-Di- or 1,2,5,6-Tetra-arylhexa-1,3,5-trienes by the Dimerization of Pd(0)-Complexed Alkenylcarbenes Generated from π‑Allylpalladium Intermediates

Pd­(0)-complexed 3-aryl or 2,3-diaryl propenylcarbenes generated from α-silyl-, α-germyl-, or α-boryl-σ-allylpalladium intermediates undergo self-dimerization to provide 1,6-di- or 1,2,5,6-tetraarylhexa-1,3,5-trienes in good to high yields. This method allows the use of a π-allylpalladium intermediate for a carbenoid precursor. Furthermore, the obtained 1,2,5,6-tetraarylhexa-1,3,5-trienes exhibit aggregation-induced emission enhancement property

Directional Energy Transfer in Mixed-Metallic Copper(I)–Silver(I) Coordination Polymers with Strong Luminescence

Strongly luminescent mixed-metallic copper­(I)–silver­(I) coordination polymers with various Cu/Ag ratio were prepared by utilizing the isomorphous relationship of the luminescent parent homometallic coordination polymers (Φ_em = 0.65 and 0.72 for the solid Cu and Ag polymers, respectively, at room temperature). The mixed-metallic polymer with the mole fraction of copper even as low as 0.005 exhibits a strong emission (Φ_em = 0.75) from only the copper sites as the result of the efficient energy migration from the silver to the copper sites. The migration rates between the two sites were evaluated from the dependence of emission decays upon the mole fraction of copper

Water-Molecule-Driven Vapochromic Behavior of a Mononuclear Platinum(II) System with Mixed Bipyridine and Thioglucose

A mononuclear platinum­(II) complex with mixed bpy and H₄tg^– ligands, [Pt­(H₄tg-<i>S</i>)₂(bpy)]·2H₂O (<b>1a</b>; bpy = 2,2′-bipyridine and H₅tg = 1-thio-β-d-glucose), is photoluminescent in the solid state and undergoes facile and reversible removal of solvated water molecules accompanied by changes in its absorption and emission wavelengths. The analogous dmbpy complex, [Pt­(H₄tg-<i>S</i>)₂(dmbpy)]·H₂O (<b>2a</b>; dmbpy = 4,4′-dimethyl-2,2′-bipyridine), is also emissive in the solid state, but its absorption and emission spectra remain unchanged after dehydration. X-ray crystallographic analyses revealed that the difference in the chromism of <b>1a</b> and <b>2a</b> is due to the difference in their hydrogen-bonding networks, which involve solvated water molecules

Photo- and Vapor-Controlled Luminescence of Rhombic Dicopper(I) Complexes Containing Dimethyl Sulfoxide

Halide-bridged rhombic dicopper­(I) complexes, [Cu₂­(μ-X)₂­(DMSO)₂­(PPh₃)₂] (X = I^–, Br^–; DMSO = dimethyl sulfoxide; PPh₃ = triphenylphosphine), were synthesized, the iodide complex of which exhibited interesting photochromic luminescence driven by photoirradiation and by exposure to DMSO vapor in the solid state. Single-crystal X-ray diffraction measurements revealed that the iodo and bromo complexes (abbreviated <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> and <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b>) were isomorphous, and that the two DMSO ligands were coordinated to the Cu­(I) ion via the O atom in both complexes. Both complexes exhibited bright blue phosphorescence at room temperature (λ_em = 435 nm, Φ_em = 0.19 and 0.14 for <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> and <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b>, respectively) with a relatively long emission lifetime (τ_em ∼ 200 μs at 77 K) derived from the mixed halide-to-ligand and metal-to-ligand charge transfer (³XLCT and ³MLCT) excited state. Under UV irradiation, the blue phosphorescence of <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b> disappeared uneventfully and no new emission band appeared, whereas the blue phosphorescence of <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> rapidly disappeared with simultaneous appearance of a new green emission band (λ_em = 500 nm). On further irradiation, the green emission of the iodide complex gradually changed to bright yellowish-green (λ_em = 540 nm); however, this change could be completely suppressed by lowering the temperature to 263 K or in the presence of saturated DMSO vapor. The initial blue phosphorescence of <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> was recovered by exposure to DMSO vapor at 90 °C for a few hours. IR spectroscopy and theoretical calculations suggest that the DMSO ligand underwent linkage isomerization from O-coordination to S-coordination, and both the occurrence of linkage isomerization and the removal of DMSO result in contraction of the rhombic Cu₂­(μ-I)₂ core to make the Cu···Cu interaction more effective. In the contracted core, the triplet cluster-centered (³CC) emissive state is easily generated by thermal excitation of the ³XLCT and ³MLCT mixed transition state, resulting in the green to yellowish-green emission. In contrast, the Cu···Cu distance in <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b> is considerably longer than that of <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b>, which destabilizes the ³CC emissive state, resulting in the nonemissive character

Photo- and Vapor-Controlled Luminescence of Rhombic Dicopper(I) Complexes Containing Dimethyl Sulfoxide

Halide-bridged rhombic dicopper­(I) complexes, [Cu₂­(μ-X)₂­(DMSO)₂­(PPh₃)₂] (X = I^–, Br^–; DMSO = dimethyl sulfoxide; PPh₃ = triphenylphosphine), were synthesized, the iodide complex of which exhibited interesting photochromic luminescence driven by photoirradiation and by exposure to DMSO vapor in the solid state. Single-crystal X-ray diffraction measurements revealed that the iodo and bromo complexes (abbreviated <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> and <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b>) were isomorphous, and that the two DMSO ligands were coordinated to the Cu­(I) ion via the O atom in both complexes. Both complexes exhibited bright blue phosphorescence at room temperature (λ_em = 435 nm, Φ_em = 0.19 and 0.14 for <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> and <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b>, respectively) with a relatively long emission lifetime (τ_em ∼ 200 μs at 77 K) derived from the mixed halide-to-ligand and metal-to-ligand charge transfer (³XLCT and ³MLCT) excited state. Under UV irradiation, the blue phosphorescence of <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b> disappeared uneventfully and no new emission band appeared, whereas the blue phosphorescence of <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> rapidly disappeared with simultaneous appearance of a new green emission band (λ_em = 500 nm). On further irradiation, the green emission of the iodide complex gradually changed to bright yellowish-green (λ_em = 540 nm); however, this change could be completely suppressed by lowering the temperature to 263 K or in the presence of saturated DMSO vapor. The initial blue phosphorescence of <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b> was recovered by exposure to DMSO vapor at 90 °C for a few hours. IR spectroscopy and theoretical calculations suggest that the DMSO ligand underwent linkage isomerization from O-coordination to S-coordination, and both the occurrence of linkage isomerization and the removal of DMSO result in contraction of the rhombic Cu₂­(μ-I)₂ core to make the Cu···Cu interaction more effective. In the contracted core, the triplet cluster-centered (³CC) emissive state is easily generated by thermal excitation of the ³XLCT and ³MLCT mixed transition state, resulting in the green to yellowish-green emission. In contrast, the Cu···Cu distance in <b>Cu</b>_<b>2</b><b>Br</b>_<b>2</b><b>-[O,O]</b> is considerably longer than that of <b>Cu</b>_<b>2</b><b>I</b>_<b>2</b><b>-[O,O]</b>, which destabilizes the ³CC emissive state, resulting in the nonemissive character