Two new bridged alkoxysilanes, bis(triethoxysilylalkyl)-N,N′-oxalylureas (alkyl = methyl or n-propyl), bearing a highly rigid and polar oxalylurea unit in the bridges, were employed as precursors of bridged silica membranes. The gas and water separation performance of the membranes prepared from the precursors using the sol–gel process was investigated. Interestingly, the membrane properties depended on the alkyl chain length. The membrane containing methylene units (alkyl = methyl) was porous and rather hydrophilic but the other with longer propylene units (alkyl = n-propyl) was non-porous and more hydrophobic. High H₂/SF₆ gas permeance ratios of 3100 and 1700, and NaCl rejections of 89 and 85% for 2000 ppm aqueous NaCl were obtained using the membranes containing methyl and n-propyl, respectively. The membrane with alkyl = methyl also showed a high CO₂/N₂ permeance ratio of 20.6 at 50°C. These results indicate the potential applications of the membranes as gas and water separation materials. Copyright © 2015 John Wiley & Sons, Ltd.

Two organosilicon polymers with donor-silicon-acceptor (D-Si-A) repeating units were prepared and their optical properties were investigated. One with bithiophene and diethynylbenzothiadiazole units as the donor and acceptor exhibits clear photoinduced electron transfer even in nonpolar cyclohexane. In contrast, for the other D-Si-A polymer with more expanded π-conjugated units, terthiophene and dithienylbenzothiadiazole, photoenergy transfer occurs efficiently in cyclohexane and electron transfer occurs only in polar benzonitrile. DFT calculations were performed to understand the different photoluminescence properties of these D-Si-A polymers.

Specific solvatochromic D-π-A-type pyridinium dyes were designed and developed as photosensitizers for dye-sensitized solar cells (DSSCs). The dyes have N-sulfobutylpyridinium or N-(carboxybutyl)pyridinium bromide as an electron-withdrawing anchoring group. The two dyes show specific solvatochromism, leading to a large bathochromic shift of the absorption band in halogenated solvents. Moreover, a dye-adsorbed TiO₂ film immersed into halogenated solvents exhibits specific solvatochromism, as does a dye solution of halogenated solvents. DSSCs based on specific solvatochromic D-π-A-type pyridinium dyes and halogenated solvents as electrolyte solvent were prepared and their photovoltaic performance investigated. It was found that the appropriate combination of solvatochromic dyes with electrolyte solution and the effective interaction between solvatochromic dyes and TiO₂ surface can lead to not only an enhancement of light-harvesting efficiency (LHE), but also efficient electron injection from the dye to the conduction band (CB) of TiO₂. This work demonstrates that the solvatochromism of organic dyes is a key consideration for high-performance DSSCs based on organic dye sensitizers.

Carbazole-type donor-π-acceptor (D-π-A) fluorescent dyes (SO1 and SO2), each containing a diphenylamino system as an electron-donating group and a nitro moiety as an electron-accepting group, have been designed and synthesized, and their photophysical properties in solution and in the solid state have been investigated. The absorption and fluorescence properties of SO1 and SO2 in solution are similar, and both dyes exhibited moderate fluorescence quantum yields. In the solid state, however, the dye SO2, with a butyl substituent on the carbazole ring, exhibited red fluorescence at around 620 nm, whereas the dye SO1, with no substituent on the carbazole ring, did not exhibit these solid-state fluorescence properties. Furthermore, the dye SO2 exhibited weak mechanofluorochromic (MFC) properties: grinding of as-recrystallized dyes induces slight bathochromic shifts of the fluorescence excitation and emission maxima. To elucidate the effects of molecular and crystal structures on the solid-state fluorescence properties, we performed semiempirical molecular orbital calculations (PM3 and INDO/S) and single-crystal X-ray structural analysis. The X-ray crystal structures of SO1 and SO2 demonstrated that a continuous intermolecular π-stacking between the fluorophores was observable in the crystal structure of SO1, but not in that of SO2. The MO calculations revealed that SO1 and SO2 have similarly large dipole moments in the ground state (μ_g ≈ 8 D). The relationship between the observed solid-state photophysical properties and the molecular and crystal structures of the carbazole-type D-π-A fluorescent dyes are discussed on the basis of experimental results and MO calculations. It is found that the formation of a continuous intermolecular π-stacking between the fluorophores causes a drastic fluorescence quenching in the solid state and that D-π-A fluorescent dyes with very large dipole moments can reduce the MFC properties, due to strong dipole–dipole interactions between the fluorophores in the solid state.

Treatment of 2,6-bis(diphenylphosphino)-4,4-bis(4-n-butylphenyl)dithienosilole with chloro(dimethylsulfide)gold(I) in acetone gave the corresponding digold complex as pale green solids. The complex was highly emissive and showed blue photoluminescence with the quantum efficiencies of Φ = 0.99 and 0.30 for its solution and powders, respectively. The complex showed good film forming properties and its spin coating from the toluene solution afforded a thin solid film that also showed emissive properties with Φ = 0.08 © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:514–517, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20715

Star-shaped molecules with pyrene-containing π-conjugated units linked by an organosilicon core (Py₃Si and Py₃C) were prepared and their applications to thin-film transistors (TFTs) and photovoltaic cells were studied. Bottom-contact type TFTs with spin-coated films of the star-shaped compounds as the active layers were prepared and the field-effect mobility (µ_FET) and I_on/I_off ratios were determined to be approximately 10⁻⁵ cm² V⁻¹ s⁻¹ and 10⁴, respectively. Photovoltaic properties of Py₃Si and Py₃C were studied in the cells, ITO–PEDOT-PSS–Py₃Si or Py₃C-PCBM–LiF–Al. Although the power conversion efficiency (PCE) of the cells was only about 0.04%, they showed high open circuit voltages (V_oc) of 0.8–0.9 V, indicating the high potential of this type of compound as a host material. Copyright © 2009 John Wiley & Sons, Ltd.