Nitrogen-Containing Carbon Tubes Fabricated by Light Irradiation.

Cotton-core/polypyrrole (PPy)-sheath fibers (cotton/PPy fibers) were synthesized by aqueous chemical oxidative seeded polymerization and were utilized as precursors for nitrogen-containing carbon (NCC) tubes. Irradiation of the cotton/PPy fibers with a near-infrared (NIR) laser heated them to approximately 300 °C due to light-to-heat photothermal conversion by the PPy, and the cotton core was thermally decomposed and vaporized. Scanning electron microscopy studies revealed the formation of tubes with monodispersed diameters, and elemental microanalysis, Fourier transform infrared spectroscopy, and Raman spectroscopy confirmed that the PPy sheath was converted into NCC. Furthermore, sunlight also worked as the light source in fabricating the NCC tubes. The thicknesses of the tubes were controlled between 410 nm and 2.30 µm by tuning the PPy sheath thickness. The method developed in this study can be extended to other polymeric fibers, including acrylic and wool fibers. The shapes of the cross sections and surface nanomorphologies of the NCC tubes can be reflected in those of the polymer/PPy fibers.

Monodispersed Nitrogen-Containing Carbon Capsules Fabricated from Conjugated Polymer-Coated Particles via Light Irradiation.

Near-infrared (NIR) light irradiation induced the transformation of polypyrrole (PPy) to nitrogen-containing carbon (NCC) material due to its light-to-heat photothermal property. The temperature of the PPy increased over 700 °C within a few seconds by the NIR laser irradiation, and elemental microanalysis confirmed the decreases of hydrogen and chloride contents and increases of carbon and nitrogen contents. Monodispersed polystyrene (PS)-core/PPy shell particles (PS/PPy particles) synthesized by aqueous chemical oxidative seeded polymerization were utilized as a precursor toward monodispersed NCC capsules. When the NIR laser was irradiated to the PS/PPy particles, the temperature rose to approximately 300 °C and smoke was generated, indicating that the PS component forming the core was thermally decomposed and vaporized. Scanning electron microscopy studies revealed the successful formation of spherical and highly monodispersed capsules, and Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy studies confirmed the capsules consisted of NCC materials. Furthermore, sunlight was also demonstrated to work as a light source to fabricate NCC capsules. The size and thickness of the capsules can be controlled between 1 and 80 µm and 146 and 231 nm, respectively, by tuning the size of the original PS/PPy particles and PPy shell thickness.

Control of aurophilic interaction: conformations and electronic structures of one-dimensional supramolecular architectures.

Gold(i) chloride complexes with the diarsenic ligands cis-1,4-dihydro-1,4-diarsinines (cis-DHDAs) were synthesized. X-ray diffraction revealed that they formed one-dimensional polymeric structures through aurophilic interactions. Their higher-ordered structures are controlled by the ligand structure; methyl- and t-butyl substituted ligands offered transoid-transoid and transoid-cisoid conformations, respectively. Density functional theory (DFT) calculations indicated that the electronic structure of the aurophilic network was highly dependent on the conformations. This is the first study on the relationship between the chain conformation and 5d-orbital structures of gold complexes.

Hall Effect in Bulk-Doped Organic Single Crystals.

The standard technique to separately and simultaneously determine the carrier concentration per unit volume (N, cm-3 ) and the mobility (µ) of doped inorganic single crystals is to measure the Hall effect. However, this technique has not been reported for bulk-doped organic single crystals. Here, the Hall effect in bulk-doped single-crystal organic semiconductors is measured. A key feature of this work is the ultraslow co-deposition technique, which reaches as low as 10-9 nm s-1 and enables us to dope homoepitaxial organic single crystals with acceptors at extremely low concentrations of 1 ppm. Both the hole concentration per unit volume (N, cm-3 ) and the Hall mobility (µH ) of bulk-doped rubrene single crystals, which have a band-like nature, are systematically observed. It is found that these rubrene single crystals have (i) a high ionization rate and (ii) scattering effects because of lattice disturbances, which are peculiar to this organic single crystal.

Practical Synthesis and Properties of 2,5-Diarylarsoles.

2,5-Diarylarsoles were easily synthesized from nonvolatile arsenic precursors. Diiodoarsine was generated in situ and reacted with titanacyclopentadienes to give 2,5-diarylarsoles. The structures and optical properties were studied in comparison with those of 2,5-diarylphosphole. It was found that the arsoles were much more stable in the air than the phosphole. Single crystal X-ray diffraction revealed the arsenic atoms adopted a trigonal pyramidal structure, reflecting on the s-character of the lone pair. The obtained 2,5-diarylarsoles and 2,5-diarylphosphole showed intense emission in solutions and solid state. In addition, the optical properties were controlled by transition-metal coordination.

Color Tuning of the Aggregation-Induced Emission of Maleimide Dyes by Molecular Design and Morphology Control.

Aggregation-induced emission (AIE)-active maleimide dyes, namely, 2-p-toluidino-N-p-tolylmaleimide, 3-phenyl-2-toluidino-N-p-tolylmaleimide, 2-p-thiocresyl-3-p-toluidino-N-p-tolylmaleimide, and 2,3-dithiocresyl-N-arylmaleimides, were synthesized by facile synthetic procedures. The dyes show intense emission in the solid state, and emission colors were controlled from green (λmax =527 nm) to orange (λmax =609 nm) by varying the substituents at the 2- and 3-positions of the maleimide and the packing structures in the solid state. 2,3-Disubstituted maleimide dyes effectively underwent redshifts of their emission wavelength. Furthermore, some of the dyes exhibited mechanochromism and polymorphism, and their emission properties were dramatically dependent on the morphology of the solid samples. The mechanisms of the emission behaviors were investigated by X-ray diffraction. The substituent of the nitrogen atom of the maleimide ring affected the intermolecular interactions and short contacts, which were observed by single crystal X-ray crystallography, to result in completely different emission properties.

As-stereogenic C2-symmetric organoarsines: synthesis and enantioselective self-assembly into a dinuclear triple-stranded helicate with copper iodide.

As-stereogenic C2-symmetric 2,5-diaryl-cis-1,4-dihydro-1,4-diarsinines (2,5-diaryl-cis-DHDAs) were synthesized without volatile precursors. A racemic mixture of the ligands enantioselectively self-assembled into a dinuclear triple-stranded helicate with copper iodide in quantitative yield. In the helicate, two metals were bridged via three enantiomerically pure ligands.

Synthesis of dithienogermole-containing oligo- and polysilsesquioxanes as luminescent materials.

Dithienogermole (DTG)-containing oligo- and polysilsesquioxanes were prepared by hydrolysis/condensation of DTGs bearing one () or two trialkoxysilyl group(s) (). The reaction of gave a cage-type octasilsesquioxane with eight DTG groups at the edges () as a viscous oil, whereas the reaction of yielded a network polymer () as a self-standing film. showed a photoluminescence (PL) quantum yield (Φ) of 56% in THF. This value was as high as that of (Φ = 58%), in spite of the accumulation of DTG units in the molecule, as characteristics of the POSS structure. The PL of in THF was suppressed by contact with nitrobenzene, showing the potential of for sensing nitroaromatic explosives. Polymer exhibited a relatively low Φ of 2% as a film, but Φ was improved to 38% by copolymerization with trimethoxymethylsilane. was also copolymerized with a trimethoxysilyl-substituted carbazole derivative () to provide polysilsesquioxanes with DTG and carbazole units, which showed efficient photo-energy transfer from carbazole to DTG in the films. Similar copolymerization of with in the presence of poly(9-vinylcarbazole) provided a composite material with hole-transporting electroluminescence properties, applicable in multi-layered organic light emitting diodes.

Selective Synthesis of cis-trans-cis Cyclic Tetrasiloxanes and the Formation of Their Two-Dimensional Layered Aggregates.

In this study, a single cyclic tetrasiloxane containing propylammonium trifluoromethanesulfonate and methyl side-chain groups (Am-CyTS) was selectively prepared by the hydrolytic condensation of 3-aminopropyldiethoxymethylsilane using aqueous superacid trifluoromethanesulfonic acid. The (1)H NMR spectrum of Am-CyTS in D2O exhibited a single signal assigned to a methyl group, and the (29)Si NMR spectrum of Am-CyTS in DMSO-d6 also exhibited only one signal. In the matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and the electrospray ionization mass spectrometry (ESI MS) analyses, the peaks corresponding to the masses of the cyclic tetrasiloxane were observed. These results indicate that Am-CyTS is a single cyclic tetrasiloxane without isomers. In addition, the result of a single-crystal X-ray structural analysis of its tert-butoxycarbonyl (Boc)-protected compound (Boc-CyTS) indicated the formation of a cis-trans-cis cyclic tetrasiloxane forming two-dimensional layered aggregates. Moreover, it was found that two-dimensional layered aggregates could be formed by drop-casting an aqueous solution of Am-CyTS and chloroform solution of Boc-CyTS onto glass substrates, as shown by powder X-ray diffraction measurements.

Preparation and electric property of polysilsesquioxane thin films incorporating carbazole groups.

New silsesquioxane incorporating a carbazole groups (PCTSQ) has been synthesized by a click thiol-ene reaction and a subsequent sol-gel reaction. To evaluate the electric property of this hybrid, diode devices have been fabricated by using PCTSQ thin film by spin-coating onto n-type ZnO film prepared by the electrodeposition method. The thin film hybrid devices showed good electric characteristics and high rectification ratio, as well as worked as a rectifier.

Polymorph control of luminescence properties in molecular crystals of a platinum and organoarsenic complex and formation of stable one-dimensional nanochannel.

The mononuclear diiodoplatinum(II) complex (trans-PtI2(cis-DHDAMe)2), where cis-DHDAMe = cis-1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(methoxycarbonyl)-1,4-diarsinine, forms three different crystalline polymorphs that can be either concomitantly or separately obtained on varying the recrystallization conditions. Cubic red crystals (α-phase) and red-orange needles (ß-phase) exhibit solid-state red emissions at room temperature. Cubic red crystals of the γ-phase show no solid-state emission at room temperature. All crystalline structures were confirmed by X-ray crystallography. Room-temperature strongly luminescent crystals (α-phase) (λem = 657 nm, Φ = 0.52) have a triclinic P1 (No. 2) structure and no voids in the crystal structure. Red-orange needle-shaped crystals of the ß-phase exhibit moderate red luminescence (λem = 695 nm, Φ = 0.09) at room temperature and have a trigonal, R3 (No. 148), structure. In the needlelike crystals of the ß-phase, stable hexagonal arrays of nanoporous channels, 5.0 Å in diameter, are formed. Room-temperature nonluminescent crystals (γ-phase) have an orthorhombic, Pbca (No. 61), structure with a void volume that is 4.9% of the total crystal volume. After heating the α-phase crystals at 150 °C for 2 min, a powder XRD pattern different from the original crystal is obtained, and its solid-state emission at room temperature decreased. After heating the ß-phase crystals at 150 °C for 2 min, the emission wavelength and the quantum yield of the solid-state emission at room temperature and the powder XRD pattern are the same as those of the α-phase after heating at 150 °C. A crystal-to-crystal transition triggered by the thermal stimulus produces a different stable polymorph of the mononuclear diiodoplatinum(II) complex. The one-dimensional nanoporous crystals encapsulated iodine without distorting the crystal packing.

Hybrid Cu(2)O diode with orientation-controlled C(60) polycrystal.

We report on a hybrid diode composed of a 2.1 eV bandgap p-cupric oxide (Cu2O) semiconductor and fullerene (C60) layer with a face-centered cubic configuration. The hybrid diode has been constructed by electrodeposition of the 500 nm thick Cu2O layer in a basic aqueous solution containing a copper acetate hydrate and lactic acid followed by a vacuum evaporation of the 50 nm thick C60 layer at the evaporation rate from 0.25 to 1.0 Å/s. The C60 layers prepared by the evaporation possessed a face-centered cubic configuration with the lattice constant of 14.19 A, and the preferred orientation changed from random to (111) plane with decrease in the C60 evaporation rate from 1.0 to 0.25 Å/s. The hybrid p-Cu2O/C60 diode showed a rectification feature regardless of the C60 evaporation rate, and both the rectification ratio and forward current density improved with decrease in the C60 evaporation rate. The excellent rectification with the ideality factor of approximately 1 was obtained for the 500 nm thick (111)-Cu2O/50 nm thick (111)-fcc-C60/bathocuproine (BCP) diode at the C60 evaporation rate of 0.25 Å /s. The hybrid Cu2O/C60 diode prepared by stacking the C60 layer at the evaporation rate of 0.25 Å/s revealed the photovoltaic performance of 8.7 × 10(-6)% in conversion efficiency under AM1.5 illumination, and the conversion efficiency changed depending on the C60 evaporation rate.

Organic vapor triggered repeatable on-off crystalline-state luminescence switching.

A nonporous crystalline solid consisting of an organoarsenic platinum(II) complex, i.e., a mononuclear diiodoplatinum(II) complex trans-PtI(2)(cis-DHDAtBu)(2) (1) with cis-1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(tert-butoxycarbonyl)-1,4-diarsinine (cis-DHDAtBu), shows on-off solid-state luminescence switching through reversible solvent vapor uptake and escape. The on-off switching of solid-state luminescence was achieved without changing the structure or electronic state of the organoarsenic platinum(II) complex.

Characterization of dimers of hydroquinone glucosides produced by peroxidase-catalyzed polymerization.

4'-Hydroxyphenyl alpha-glucoside and 4'-hydroxyphenyl beta-glucoside were polymerized with horseradish peroxidase. The isolated dimers were found to have linkages at C3' of the hydroxyphenyl moieties and proved to be fluorescent. Low accumulation of oligomers was attributed to increasing electrochemical reactivity with polymerization degrees, which were expected from the levels of highest occupied molecular orbital.

A quadrupole-quadrupole stacking synthon in (2,3,5,6-tetrafluorobenzenethiolato-kappaS)(triphenylphosphine-kappaP)gold(I).

The title compound, [Au(C6HF4S)(C18H15P)], with both aromatic and fluorinated aromatic rings in its molecular system, shows dimerization through a quadrupole-quadrupole stacking synthon. The dimer further aggregates through intermolecular pi-pi stacking and C-H...pi interactions, giving a supramolecular three-dimensional network.

Tetra-n-butylammonium tetrakis(pentafluorobenzenethiolato-kappaS)aurate(III).

The title compound, (C(16)H(36)N)[Au(C(6)F(5)S)(4)], is the first example of a structurally characterized gold(III) complex with monodentate benzenethiolate ligands. The Au atom lies on a fourfold axis and the AuS(4) group has square-planar geometry. The anion shows a two-dimensional linkage through pi-pi and C-F...pi intermolecular interactions.