Synthesis and characterization of "hairy urchin"-like polyaniline by using β-cyclodextrin as a template

A novel synthesis of "hairy urchin"-shaped polyaniline (PAni) and its surface coverage with nanospikes was achieved from a simple microemulsion polymerization technique in the presence of β-cyclodextrin (β-CD). The rodlike micelle phase was characterized, and the key factors affecting the formation of PAni nanostructures were systematically examined. Ferric chloride (FeCl(3)) has played a role as a structural directing agent to fabricate the polymer as hairy urchin-like structure/nanorods via a cooperative interaction between FeCl(3) and DoTAC in an aqueous medium. Host-guest inclusion complex of β-cyclodextrin with aniline was used as a monomer. It has been revealed that the formation of the supramolecular complexes of polyaniline with β-CD due to host-guest interaction is indispensable for the fabrication of these unique PAni nanostructures, and a suitable β-CD to aniline molar ratio is essential to their exclusive formation. Different varieties of PAni nanostructures such as hairy urchin, branched particles consisting of rodlike branches, and regular rodlike particles were obtained in the presence of FeCl(3). Also, in the absence of FeCl(3), a predominant product of regular spherical particles and wirelike aggregation exhibiting faceted surfaces were obtained. The structures of polyaniline hairy urchin-like nanorods were analyzed using transmission electron microscopy (TEM). The synthesized polymer was characterized by Fourier-transform infrared spectroscopy and X-ray diffraction technique. Additionally, the relationship between the morphology and the conductivity of the PAni nanostructures was investigated as well.     

Sorption von Wasserdampf an Poly-L-Lysinhydro-bromid

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Dye-sensitized solar cells based on donor-π-acceptor fluorescent dyes with a pyridine ring as an electron-withdrawing-injecting anchoring group

A new‐type of donor–acceptor π‐conjugated (D‐π‐A) fluorescent dyes NI3 – NI8 with a pyridine ring as electron‐withdrawing‐injecting anchoring group have been developed and their photovoltaic performances in dye‐sensitized solar cells (DSSCs) are investigated. The short‐circuit photocurrent densities and solar energy‐to‐electricity conversion yields of DSSCs based on NI3 – NI8 are greater than those for the conventional D‐π‐A dye sensitizers NI1 and NI2 with a carboxyl group as the electron‐withdrawing anchoring group. The IR spectra of NI3 – NI8 adsorbed on TiO₂ indicate the formation of coordinate bonds between the pyridine ring of dyes NI3 – NI8 and the Lewis acid sites (exposed Tiⁿ⁺ cations) of the TiO₂ surface. This work demonstrates that the pyridine rings of D‐π‐A dye sensitizers that form a coordinate bond with the Lewis acid site of a TiO₂ surface are promising candidates as not only electron‐withdrawing anchoring group but also electron‐injecting group, rather than the carboxyl groups of the conventional D‐π‐A dye sensitizers that form an ester linkage with the Brønsted acid sites of the TiO₂ surface.     

Detection of water in organic solvents by photo-induced electron transfer method

A new class of fluorescence sensor for detection of water in organic solvents based on photo-induced electron transfer (PET) of anthracene coupled with an amino acid has been designed and developed.     

Jasisoquinolines A and B, architecturally new isoquinolines, from a marine sponge Jaspis sp

Two architecturally new isoquinolines, jasisoquinolines A and B, were isolated from a marine sponge Jaspis sp. as cathepsin B inhibitors. Their structures were determined by a combination of spectroscopic analyses and chemical methods. Both jasisoquinolines A and B inhibit cathepsin B with an IC(50) value of 10 μg/mL.     

Fluorescence PET (photo-induced electron transfer) sensors for water based on anthracene-boronic acid ester

Anthracene-boronic acid ester as a new class of fluorescence PET sensors for detection of a trace amount of water in organic solvents has been designed and developed.     

Preparation of siloxy focal dendron-protected TiO2 nanoparticles and their photocatalysis

TiO2 nanoparticles were synthesized at approximately 0 degrees C by hydrolyzing [(CH3)2CHO]4Ti in 1-propanol solutions of poly(amido amine) dendrons with a siloxy focal point and long alkyl chain spacers. Transmission electron microscopic photographs showed that TiO2 nanoparticle was 1-5 nm in size and protected by dendrons, when prepared at a mixing ratio 1:10 of Ti ion and dendron. At higher contents of Ti ion, TiO2 nanoparticles aggregated up to a maximum size of 90 nm, depending on the dendron generation (first to third). It was confirmed from X-ray photoelectron spectroscopy that Si-O-Ti covalent bond was formed in dendron-protected TiO2 nanoparticles. The ability of dendron-protected TiO2 nanoparticles as a photocatalyst for the photodegradation of 2,4-dichlorophenoxyacetic acid was higher than that of nonprotected nanoparticle and superior at higher generation. It was suggested that the dendrons protecting TiO2 nanoparticle have enough void volume to conserve guest molecules and behave effectively as a reservoir of guest molecules.     

Solubilization properties of aqueous solutions of alkyltrimethylammonium halides toward a water-insoluble dye

The solubility of a water-insoluble dye, Sudan Red B, in aqueous sodium halide solutions of tetradecyl-, cetyl-, and stearyltrimethylammonium halides has been measured at different surfactant and salt concentrations, and the dependence of solubilization properties on alkyl chain length has been discussed with reference to the micelle size and shape. At low ionic strengths where only spherical micelles exist, the solubilization power of micellar surfactant slightly increases with increasing the ionic strength, but it sharply increases at high ionic strengths above the threshold value of sphere-rod transition. However, the solubilization power becomes independent of the ionic strength, if their rodlike micelles are sufficiently long. The solubilization capacity increases linearly with increasing the molecular weight, almost independent of counterion species, but the rod-like micelle has a higher solubilization capacity than the spherical micelle. The solubilization capacity is larger for a surfactant with longer alkyl chain, indicating that the dye is solubilized more readily in a larger hydrophobic core. The solubilized dye is situated in a rodlike micelle of alkyltrimethylammonium halides, on average, 4.5–7.5 nm apart from each other.     

P NMR investigation of a ringing gel phase and adjacent phases

The temperature-surfactant concentration phase diagram was examined for the dodecyltrimethylammonium dimethylphosphate/3-methyl-3-methoxybutanol/water ternary system. The phase diagram contained a highly elastic gel phase which is known as a “ringing gel phase”. The ringing gel phase and adjacent phases in the ternary system were investigated by polarized optical microscopy, freeze-fracture transmission electron microscopy, and ³¹P NMR. Globular textures were observed in an optically isotropic gel phase. Since the globules were larger than those found in an isotropic solution, the texture consists of domains of aggregated units in the cubic (I₁) phase. Structure units of domains are equivalent to microemulsions which are constructed by surfactant molecules and swollen by alcohol in the isotropic (L₁) phase. Characteristic polarized microscopic textures were visualized in two phases with higher surfactant concentrations. These phases were identified as being hexagonal (H₁) and lamellar (L) liquid crystals which was confirmed by transmission electron microscopy. The ³¹P NMR signal of the ringing gel showed a sharp singlet the same as that of the L₁ phase, indicating the fully averaged anisotropic interaction of the aggregates. The characteristic NMR signals of the anisotropic hexagonal and lamellar liquid crystal phases displayed chemical shielding with an asymmetric lineshape.