Ring-fluorinated fluoresceins as an organic photosensitizer for dye-sensitized solar cells using nanocrystalline zinc oxide

Four kinds of ring-fluorinated fluoresceins and sulfofluorescein from tetrafluororesorcinol and/or tetrafluorophthalic anhydride have been synthesized and the photochemical properties of the zinc oxide nanocrystalline electrode sensitized by the ring-fluorinated fluoresceins were investigated.     

Hemiacetal and hemiaminal formation at fluoroacyl moiety

Hemiacetals and hemiaminals were produced not only at a trifluoroacetyl (CF₃CO) moiety but also at difluoroacetyl (CHF₂CO) and pentafluoroalkanoyl (C₂F₅CO) moieties. As larger was the electron-withdrawing nature and less bulky was the fluoroalkyl (R_f) group and smaller was the size of an alcohol, the ratio of hemiacetal form increased. Not only a CF₃CO moiety but also monofluoroacetyl (CH₂FCO), CHF₂CO, and C₂F₅CO moieties produced the hemiaminals. As larger was the electron-withdrawing nature of R_f group and smaller was an amine, the ratio of hemiaminal form increased.     

Crystal Structures, and Electrical Conducting and Magnetic Properties in the Plate Crystals of (Ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide)2·MX4 (M=Fe, Ga, X=Br; M=Fe, X=C1) Salts

By the reaction of a new donor molecule, ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide (1) with FeBr₃, GaBr₃ or FeCl₃ in CH₃CN/CS₂ charge transfer (CT) salts of 1 with counteranions of FeBr₄⁻, GaBr₄⁻ or FeCl₄⁻ (1₂·FeBr₄, 1₂·GaBr₄ and 1₂·FeCl₄) as plate crystals were obtained. Their crystal structures are apparently similar to each other, in which 1 molecules are dimerized in the parallel direction of their molecular long axes, and the dimers are stacked with changing the direction of the molecular long axes alternately to form a one- dimensional column. The counteranions intervene between the 1-stacked columns and are aligned in a zigzag manner. The room-temperature electrical conductivities of 1₂·FeBr₄ and 1₂·GaBr₄ are fairly high (10-15 S cm⁻¹), but a small value (0.8 S cm⁻¹) is obtained for 1₂·FeCl₄. For all CT salts, temperature dependences of electrical conductivity are semiconducting in spite of very small activation energies (30-90 meV). Based on the comparison between their electrical conducting and magnetic properties, it is suggested that the d spins of FeBr₄⁻ or FeCl₄⁻ ions exert almost no influence on the π conducting electrons in the 1-stacked column.     

Effects of protonation of alkyldimethylamine oxides on the dissolution temperature in aqueous media

The effects of protonation (ionization) of hexadecyldimethylamine oxides on the dissolution temperature in aqueous media were investigated by differential scanning calorimetry. Only one endothermic peak was reproducibly observed at all the degrees of ionization alpha examined that were assigned to the transition from the solid (the gel phase) to the solution containing micelles. The dissolution temperature versus alpha curves showed a maximum at alpha=0.5, strongly suggesting the formation of a stable complex of 1-to-1 composition of the nonionic and cationic species through the proposed hydrogen bond. From the shape of the dissolution curve as well as the composition analysis of the solid phase, the solid solution was found to be formed over all alpha values. Effects of alkylchain length on the dissolution temperature for a homologous series of octadecyl- (C18DAO), hexadecyl- (C16DAO), and tetradecyldimethylamine oxide (C14DAO) were also examined for alpha=0.5 and alpha=1. Both the transition temperature and the associated thermodynamic quantities DeltaH and DeltaS increased systematically with the chain length, but for alpha=0.5 smaller increases in DeltaH and DeltaS values with the chain length were observed [DeltaH/CH2 (kJ mol(-1))=7.2+/-0.2 and 2.2+/-0.5 for alpha=1 and alpha=0.5, respectively, and DeltaS/CH2 (J mol(-1) K(-1))=21.9+/-1.8 for alpha=1 and 4.6+/-1.9 for alpha=0.5]. By annealing procedures, the metastable nature of the gel phase was demonstrated for the C16DAO (alpha=1) solid.     

Infrared study of proton-deuteron mutual diffusion in a CsHSO4/CsDSO4 solid under high pressure

Proton-deuteron mutual diffusion in a CsHSO₄/CsDSO₄ solid at 373 K was examined up to 3 GPa by an infrared mapping measurement. Phases HPHT1 and HPHT2 appeared at 1.5 and 2.3 GPa, respectively, after heating. These phases were found to be stable at room temperature, while phase IV, which appeared on compression at room temperature, was metastable. The pressure dependence of the proton-deuteron mutual diffusion coefficient was determined from the temporal change in the deuteron distribution of the solid. The coefficient decreased from 7×10⁻¹⁶ to 1×10⁻¹⁶ m²/s during the transition from phase II to HPHT1 at 1.5 GPa, and showed no significant change during the transition to phase HPHT2. These results suggested that in addition to the hydrogen bond length, other structural factors might also have had an influence on the rate of diffusion.     

Method for measuring the phase error distribution of a wideband arrayed waveguide grating in the frequency domain

We describe a method for measuring the phase error distribution of an arrayed waveguide grating (AWG) in the frequency domain when the free spectral range (FSR) of the AWG is so wide that it cannot be covered by one tunable laser source. Our method is to sweep the light frequency in the neighborhoods of two successive peaks in the AWG transmission spectrum by using two laser sources with different tuning ranges. The method was confirmed experimentally by applying it to a 160 GHz spaced AWG with a FSR of 11 THz. The variations in the derived phase error data were very small at +/-0.02 rad around the central arrayed waveguides.     

Excited-state intramolecular proton transfer (ESIPT) fluorescence from 3-amidophthalimides displaying RGBY emission in the solid state

Fluorescence properties of phthalimide derivatives (1) incorporating sulfonamide and acetamide functionalities at the 3-position were investigated both in solution and in the solid states to reveal the effects of the amide functionalities on the fluorescence properties. In the solid state, sulfonamides 1a and 1b, respectively, gave off red (λ^F_max 595?nm) and green (λ^F_max 537?nm) emission through an ESIPT process. Acetamides 1c and 1d, respectively displayed blue (λ^F_max 432?nm) and yellow (λ^F_max 560?nm) emission. Through simply modifying the amide functionality, phthalimide 1 displayed multicolor RGBY emission in the solid state.     

Rapid spectrophotometric determination of iron in natural waters with 4-(2-thiazolylazo)-6-chlororesorcinol

4-(2-Thiazolylazo)-6-chlororesorcinol reacts sensitively with iron(II) to form a water-soluble brown complex which has a characteristic absorption at 741 nm. By utilizing this absorption, rapid and selective spectrophotometric determination of iron has been developed. The absorbance is constant at pH 8.7 to 10.9 and Beer's law holds up to 1.8 ppm of iron, with a molar absorptivity of 3.13 × 10⁴ liters mol^?1 cm^?1. Many types of ions are tolerable and the method has been applied successfully to the determination of iron in river waters.     

Responsive microstructures on organic–inorganic hybrid films

Micro-periodic structures exhibiting shape memory have been fabricated on organic–inorganic hybrid films. The microscale structures are obtained by forming wrinkles via buckling of the stiff surface layer. The surface-modified layers are obtained by surface photopolymerization or by oxidation of the hybrid films. The microscale structures are spontaneously formed by the shrinkage of the underlayer via gelation. The surface microstructures on titania- or silica-based films with hydrophilic swellable polymers exhibit a humidity response, i.e., a shape memory effect. This is observed when the surface microstructure disappears and is subsequently recovered with cyclic variation of the surrounding humidity. Micro-rolls are also fabricated by the selective swelling of surface-modified layers.     

Commercially available simple ionic liquids-promoted dehydrative carbon–carbon bond-forming reaction of diarylmethanols and triarylmethanols with pyrroles,thiophene, furan and indoles

Two commercially available simple ionic liquids, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-ethyl-2,3-dimethylimidazolium trifluoromethansulfonate, effectively promote the solvent-free dehydrative carbon–carbon (C–C) bond-forming reaction of a variety of diarylmethanols and triarylmethanols with π-rich heteroaromatics, such as pyrroles, indole, furan, and thiophene without ring-opening and polymerization to give the corresponding not only 2-substituted pyrroles, furan, and thiophene but also 3-substituted indoles in good to excellent yields with moderate to excellent regioselectivities. These dehydrative C–C bond formation reactions of alcohols offer several advantages, such as the use of stoichiometric amounts of π-rich heteroaromatics and ionic liquids, water is the only by-product, there is no need for either organic solvents or expensive metal or strong Brønsted acid catalysts in the reaction, and the diversity of diarylmethylation and triarylmethylation.