Incorporation of a [2.2]paracyclophane skeleton into a conjugated polymer main chain affords a polymer comprising stacked π-electron systems. In this article, we describe the synthesis and optical properties of some [2.2]paracyclophane-based polymers on the basis of the results of our resent research. We discuss the role of [2.2]paracyclophane in the polymer backbone, through-space conjugation of the polymer, and the feasibility of using the titled polymers as single molecular wires that allow for unidirectional energy and charge transfer via through-space interactions.
A novel sodium germanomolybdate compound [Na6(H2O)12][H2Ge2Mo6O26] (1) has been successfully synthesized by conventional solution method. The structure was determined by single-crystal X-ray diffraction analysis and further characterized by IR and UV spectroscopy and X-ray powder diffraction (XRPD). X-ray structural analysis reveals that 1 crystallizes in triclinic space group P1, with lattice constants a = 8.466(4) Å, b = 10.290(4) Å, c = 11.159(5) Å, α = 72.305(6)°, β = 71.115(6)°, γ = 76.969(5)°, V = 867.5(6) Å, and Z = 1, which consists of a novel polyoxoanion [H2Ge2Mo6O26]6− and a [Na6(H2O)12]6+ cluster. Furthermore, the dimeric polyoxoanion units link alternate [Na6(H2O)12]6+ clusters to generate a 3D framework.
Ultrafine SnO2 nanoparticles were successfully synthesized by microwave heating. The SnO2 nanoparticles worked as a rechargeable electrode material for a lithium-ion battery. Micro-Raman spectroscopy, X-ray diffraction, and cyclic voltammetry studies of the SnO2 nanoparticles elucidated that the lithium insertion–deinsertion reactions during the 1st cycle were caused by both redox of SnO2 and Li–Sn alloying–dealloying reactions. The redox reactions were irreversible and disappeared via charge–discharge cycling, and only the Li–Sn alloying–dealloying reactions took place at the later cycle.
Chemical surface modifications of Al2O3, TiO2, and SiO2 by using diphenylsilane bearing hydrosilyl moieties were investigated by IR spectroscopy and gas chromatography. The hydrosilane was observed to adsorb on the metal oxide surfaces by forming Si–O–metal bonds with generation of hydrogen gas. The results show that hydrosilanes can be used as chemical surface modifiers such as the usual silane coupling agents of silanols, chlorosilanes, and alkoxysilanes.
An open-tubular capillary chromatography system has been developed using a ternary mixed solvent mixture, i.e., water–hydrophilic/hydrophobic organic solvent mixture as a carrier solution. In this study, the influence of adding surfactants to an analyte solution on separation performance was examined in a chromatographic system using a fused-silica capillary tube (75 µm inner diameter and 100 cm effective length) and a ternary mixture of water–acetonitrile–ethyl acetate (3:8:4 volume ratio) carrier solution. Sodium dodecyl sulfate (anionic), ethylhexadecyldimethylammonium bromide (cationic), and Triton X-100 (nonionic) were used as surfactants. Model analytes, 1-naphthol and 2,6-naphthalenedisulfonic acid, were separated in this order by adding the anionic and nonionic surfactants. These surfactants in the analyte solution greatly improved the separation performance (theoretical plate numbers for 2,6-naphthalenedisulfonic acid; >10000) compared with the same separation performed in the absence of surfactants. On the other hand, the analytes were not separated at all using a cationic surfactant.
This study examines the direct preparation of poly(acrylic acid) (PAA) on a silicon wafer modified by γ-ray radiation. Using this innovative method, we synthesized PAA on a silicon wafer without additive material because the silicon-wafer itself acts as an initiator. The reaction time was adjusted to control the thickness of PAA on the silicon wafer.
Normal vibrational modes of heme have been analyzed using density functional theory, to assign a new Raman band observed at 312 cm−1 in the CO-bound, active form of soluble guanylate cyclase. The conserved YxSxR motif is incorporated into the model to reproduce the hydrogen-bonding network around propionates. A delocalized mode that involves Arg motions as well as pyrrole tilting and propionate bending is found to be the most likely candidate accounting for the new band.
A new acridine fluoroionophore derivative bearing lithium salt of thioglycolate, is designed and synthesized. Its fluorescence sensing behavior toward metal ions has been investigated in absolutely aqueous media (HEPES buffer solution, pH 7.4). It displayed a selective CHEF (chelation-enhanced fluorescence) effect toward Cd2+ in presence of other heavy and transiton-metal ions. Highly sensitive switching on response of the fluorophore toward Cd2+, facilitates it suitable for sensing of Cd2+ in aqueous media.
An atom-efficient and green synthetic route to highly valuable imides (54–92% yields) from terminal alkynes and amides has been developed. This new route is composed of two consecutive reactions, that is, (i) the reported Cu(OH)2-catalyzed cross-coupling of terminal alkynes and amides to ynamides and (ii) the Sn–W mixed oxide-catalyzed regioselective hydration of ynamides.
A novel pillaring procedure without alkylamine or tetraalkylammonium pretreatment has been developed to prepare SiO2/TiO2 pillared layered manganese oxide with large surface area. SiO2/TiO2 pillared layered manganese oxide is prepared by solvothermal treating H-type layered manganese oxide at 220 °C for 12 h in a mixed solution of absolute ethanol, tetraethylorthosilicate, and titanium isopropoxide. The obtained SiO2/TiO2 pillared layered manganese oxide is expected to be a selective catalyst or an improved battery material.
Single-walled carbon nanotubes (SWNTs) with highly graphitized structure were synthesized by thermal chemical vapor deposition using an improved nitrogen-pretreated Fe–Mo/MgO catalyst. The effects of nitrogen pretreatment of Fe–Mo/MgO on the structure and properties of SWNTs were studied by TEM, Raman spectroscopy, and TGA. The investigations revealed that the nitrogen pretreatment of the catalyst promoted the growth of SWNTs. It also enhanced the structural features and thermal properties of SWNTs.
From prokaryotes to eukaryotes, the DNA condensation process by basic proteins is essential to store the genome in vivo. The surface charge inversion with a DNA/HCcp3 charge ratio of 0.7/1 indicates a role for HCcp3-mediated counter ion-driven mechanism in DNA condensation. The formation of the cholesteric liquid-crystalline phase of DNA–HCcp3 complexes occurred when DNA charges were neutralized. The results suggest that DNA condensation processes by HCcp3 can be divided into two distinctive binding stages: the first state, prior to condensation, involves an entropy-driven binding process of HCcp3 to the DNA, while the second state is an electrostatically driven condensing and assembling process.
A simple and easily controllable immobilization method for photosensitizer dyes and the resulting photosensitizer dye nanoparticle-coated membranes (PDNMs) that generate singlet oxygen (1O2) under atmospheric conditions were demonstrated. A 100% porphyrin nanoparticles layer that is less than 1 µm thick on a membrane filter caused quantitative 1O2 production under illumination. The thin layer promotes effective light absorption as well as significantly slowed deactivation of 1O2 by supporting materials. Moreover, the PDNMs were highly resistant to photobleaching of dye itself.
Cyclophanes consisting of diethylene glycol-substituted oligothiophene units as a component have been synthesized. Formation of pseudorotaxane arising from complexation of the cyclophanes and the cyclobis(paraquat-p-phenylene) (CBPQT4+) has been confirmed. It has also been discovered that conformational properties of the cyclophanes are strongly affected by the formation of pseudorotaxane.
Spherical reunion powders composed of tetragonal and cubic phase ZrO2 have been prepared for the first time via a coupling route of w/o (water in oil) emulsion with dimethyl oxalate homogenous precipitation. The as-prepared ZrO2 microspheres and the precursor powders were analyzed and characterized by TG-DTA, XRD, and SEM. The formation mechanism of these powders is discussed in detail. Experimental results indicate that the coupling route may accomplish the one-step synthesis of ZrO2 microspheres possessing well-rounded spherical shape and narrow size distribution, which consists of closely attached nanoparticles, the microspheres are approximately 5–10 µm in size.
Amorphous TiS3 active materials were prepared using a high-energy ball mill and first applied to all-solid-state cells with Li2S–P2S5 solid electrolyte. The solid-state cell operated as a rechargeable lithium battery with a high capacity of 400 mA h g−1 at room temperature. The cell exhibited a higher capacity than a solid-electrolyte cell with crystalline TiS2 and showed better cyclability than a liquid-electrolyte cell with crystalline TiS3.
We found that AlPO-5 crystals can be synthesized at relatively low temperature (120 °C) by hydrothermal reaction. The critical requirement was the adjustment of the gel composition to control the crystallization rates of aluminophosphate phases. The obtained products showed almost the same pore characteristics compared with the reference products synthesized at high temperature.
The direct and stable conversion of ethanol to propene with yields up to 60 mol % was achieved on scandium-modified indium oxide catalysts at 823 K in the presence of water and hydrogen. The reaction pathways are also suggested, ethanol → acetaldehyde → acetone → propene, which is quite different from those on zeolites and on nickel ion-loaded silica catalysts.
The applicability of 4-trimethylsilylpyridine (4TMSpy) was investigated as an organic additive to the electrolyte solution of dye-sensitized solar cells. The N3-sensitized solar cell with 4TMSpy showed higher light-to-electric energy conversion efficiencies than that with the ordinary organic additive of 4-tert-butylpyridine by a factor of ca. 1.1. This improvement of the photovoltaic performance was considered to be due to the bulkiness and peculiar electronic properties of the trimethylsilyl group.
Intelligent polymer was extendedly applied to fabricate a novel environmentally responsive Fenton catalyst in this study. The obtained magnetite/sodium carboxymethyl cellulose-graft-poly(acrylic acid) (Fe3O4/CMC-g-PAA) nanocomposites showed perfect superparamagnetism, pH response, and superior catalytic activity. In a wide range of pH (3–9), the highly swollen polymer coating not only favored the dispersion of Fe3O4 nanoparticles and protected them from leaching but also promoted interface mass transfer with large amounts of hydrophilic ingredients.
In the low-temperature water–gas shift reaction, the effect of the catalyst pretreatment conditions on the adsorption state of CO was investigated on a structured copper-based catalyst, which was prepared by electroless plating. The amount of CO adsorbed on the catalyst was higher due to the oxidation pretreatment than that by the reduction treatment. The CO adsorbed on the oxidized catalyst formed many carbonate and carboxylate species, which have a slightly weak adsorption. Such an adsorption state would enhance shift performance.
Methyl-terminated Si(111) surface was successfully fabricated using a photochemical grafting technique. This methylated surface was formed by illuminating visible light onto a hydrogen-terminated Si(111) surface that was immersed in a Grignard–tetrahydrofuran solution. It had an oxide-inhibiting property and atomically flat surface. In addition, the water contact angle improved with grafting parameters such as illumination time and light intensity and went as high as (89.0 ± 0.80)°. This improvement was associated with the increase in the fraction of the silicon surface grafted with methyl groups.
A chiral polyfluorene–thiophene derivative incorporating two different chiral side chains was synthesized via the Suzuki coupling reaction. Upon photoexcitation, thin films of the polymer exhibited efficient circularly polarized luminescence in the visible range, even without thermal annealing. The dissymmetry factor, glum, of films with thicknesses less than 100 nm reached 0.2 at 505 nm.
Short peptides with or without host–guest-bridges on their side chains were prepared and the helix content was examined in the absence or in the presence of the host–guest-bridge breaker. While a short peptide without host–guest-bridge had 14% helix content, a short peptide with host–guest-bridge had 40% helix. This helix content hardly changed after the host–guest-bridge was removed. Host–guest-bridge acts as an initiator for helix folding in the short peptide.
A facile synthetic strategy to prepare single-sized colloidal CdTe assemblies with bright band gap emission is described in this letter. In contrast to traditional approaches, the preparation of trioctylphosphine telluride (TOPTe) was not required for this synthesis, and our approach follows a one-step reaction. The CdTe magic-sized quantum dot (MSQD) assemblies were sequentially grown in this approach, and the thermodynamic equilibrium of CdTe MSQDs sequential growth was proposed.
The Friedel–Crafts-type carboxylation of arenes has been achieved by activating CO2 with silylium borates. The reaction exhibits broader substrate applicability than does our previously reported AlX3/R3SiX-mediated carboxylation.
A superhydrophobic ZnS film was successfully fabricated by a simple solvothermal method using Zn foil and S powder as raw materials in an absolute ethanol solution at 160 °C for 8 h. The products were characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle (CA) measurements. The results show that the obtained ZnS film was hexagonal phase, composed of many dense and uniform interconnected nanoflakes of average thickness ca. 120 nm. A possible reaction mechanism was proposed and discussed. It was found that the ZnS film exhibits superhydrophobicity owing to its special nanoflake structure.
Acridone is an attractive fluorescent molecule for use in DNA probes. Sensing molecule, which has acridone as a signaling moiety and DNA aptamer as a recognition moiety, was prepared by postsynthetic modification method. The fluorescence of this sensing molecule changed depending on the DNA structure and L-argininamide could be detected by this molecule. This strategy could provide a quencher-free aptamer beacon.
Thiourea dioxide in water was found to be an efficient and reusable organocatalytic system for the one-pot synthesis of polyhydroquinoline derivatives via the Hantzsch-type coupling of aldehyde, dimedone, acetoacetate, and ammonium acetate under mild reaction conditions. Operational simplicity, the use of an economically affordable catalyst, environmentally benign conditions, high product yields, and reusability of the catalyst system were the advantageous features of the developed method.
A new compound, B,B′,B′′-tris(4-hydroxyphenyl)-N,N′,N′′-triphenylborazine (BZ) was prepared as a precursor for carbon-based oxygen reduction catalysts. The mixtures of BZ and phenolic resin were pyrolyzed under N2 at 1000 °C for 5 h and resulted in a carbonaceous material with high oxygen and boron contents. The oxygen reduction catalytic activity was much improved by the addition of this precursor. The improved catalytic activity is probably due to the oxygen-containing functionalities that are enriched in the presence of boron species.
Chiral Ag:SG (glutathione) triangular nanoplates were synthesized by substitution reaction of achiral Ag:poly(vinylpyrrolidone) (PVP) nanoplates with glutathione free GSH molecules. Analysis of the chiroptical properties of the synthesized nanoplates using a circular dichroism spectrometer revealed characteristic Cotton effects with wavelengths that corresponded well to those of plasmon resonances for Ag nanoplates. X-ray photoelectron spectrometry analysis of their chemical compositions revealed that complete substitution of PVP molecules with GSH molecules proceeds on the nanoplates.
We examined the 13C/12C and 18O/16O stable isotope ratios (δ13C, δ18O) of ascorbic acid from acerola and of synthetic origin. Although the obtained δ13C values were partially overlapping for the two species, δ18O values were higher for ascorbic acid from acerola, than values obtained for synthetic ascorbic acid. From this study, it was demonstrated that carbon and oxygen isotopic composition analysis can discriminate ascorbic acid from acerola from that of synthetic origin.
A crosslinked poly(allylamine) was prepared by copolymerization of allylammonium dihydrogen phosphate with N,N′-diallyl-1,3-diaminopropane bis(dihydrogen phosphate). This polymer has both a high phosphate adsorption capacity and a low degree of swelling. Thus, the polymer should be useful as a therapeutic agent for hyperphosphatemia, and compared with sevelamer hydrochloride, should have fewer side effects such as constipation.
We report efficient carrier injection characteristics in liquid organic light-emitting diodes (OLEDs). The use of a liquid carbazole substituted with a poly(ethylene oxide) (PEO) chain provided a substantial improvement in carrier injection compared to devices constructed with carbazoles without PEO units. The external electroluminescence quantum efficiency (ΦEL) of an OLED with the liquid carbazole as an emitting layer resulted in ΦEL = 0.75%, 25 times higher ΦEL than that of our previous liquid OLED without electrolyte.
Oligoacenes are of interest as organic p-type semiconductors for use in electronic devices, but their use as n-type semiconductors is limited. N-Heteroacenes have been investigated as oligoacene-based n-type semiconductors due to their enhanced electron affinity. Herein, we report the synthesis, X-ray crystal structures, electrochemical, and field-effect transistor properties of TANC and BTANC.
PhI(OAc)2-mediated dehydrogenation of α-alkyl-β-dicarbonyl compound has been developed to afford α-ylidene-β-dicarbonyl compounds with high stereoselectivity under mild conditions. This process provides a complementary entry to stereoselectivity for the Knoevenagel reaction.
High-purity spherical silica nanoparticles have been successfully synthesized using powder quartz as silica sources in an improved sol–gel method. The effects of the modulus (molar ratio SiO2/Na2O) of sodium silicate and poly(ethylene glycol) (PEG) on the properties of silica nanoparticles were investigated. The results suggested that with the increase of modulus, the purity of silica nanoparticles increased. The higher purity (99.92 wt %) products can be obtained from the modulus of 3. Moreover, it was also found that the particle size, distribution, and dispersion significantly depend on the concentration of PEG. The silica nanoparticles with average size of 60 nm are well-dispersed and show a narrow size distribution when the PEG concentration is 2 wt %. The results suggest that it is feasible to prepare high-purity spherical silica nanoparticles using powder quartz as silica sources.
In the search for new ionic liquids (ILs) for biomass processing, analytical chemistry, or modern nonvolatile fire retarding agents, alkyl phosphonate-based ILs represent very promising candidates. A very practical synthesis of such ILs, which is superior to the conventional quaternization of 1-alkylimidazoles by dimethyl phosphite (DMP), was developed. 1,3-Dialkylimidazolium halide salts serve as convenient starting materials, and various 1,3-dialkylimidazolium methyl phosphonates are thus accessible by simple, fast, and solvent-free procedures with DMP, where the anion is methylated.
Mesoporous solid acid catalyst composed of Nb–Mo oxide was prepared via a hydrothermal synthesis employing ammonium niobium oxalate and hexaammonium heptamolybdate tetrahydrate as the precursors. The assembly of fine particles with diameters of 20–34 nm was observed by field emission–scanning electron microscopy. The Nb–Mo oxide has mesopores with diameters of 1.6–2.0 nm. It was possible to tune size of the primary particles and diameter of the mesopores by changing Mo/Nb ratio. The Nb–Mo oxide exhibited high activity in Friedel–Crafts alkylation.
Quinone dimers are readily prepared quantitatively from 2-sulfanyl-1,4-dimethoxybenzene by oxidative treatment. The oxidative coupling progressed in a highly regioselective manner. Removal of O-protection and subsequent oxidation gave 5,5′-bis(sulfanylquinone) dimer in good yields. Physical properties of the dimer derivatives are also investigated.
We observed the condensation of water and ethanol on a hydrophobic polymer film coated with fluorinated silicone particles and identified five states: the circular droplet, ellipsoidal droplet, network, huge droplet, and film states. The shape of the condensed droplets changed with the particle density and the wettability of the particles by the liquid.
In this study, we synthesized a new trehalose-based amphiphile, 6,6′-di-O-octyltrehalose, from trehalose by five reaction steps. The SEM and TEM images of the sample prepared by drying its aqueous dispersion showed the formation of morphologically controlled hollow rod nanoaggregates.
We have synthesized diphenyl-substituted anthra[2,3-b:6,7-b′]difuran, a furan analogue of pentacene, together with its isomers, anthra[2,1-b:6,5-b′]difuran and anthra[1,2-b:5,6-b′]difuran. These compounds are stable in the solid state with high decomposition temperatures. They are luminescent in the solid state with a quantum yield of 0.093–0.23.
We successfully determined the three-dimensional structure of agar gel droplets on multipillared surfaces. The contact angle, length of penetration of the agar gel into the interspace between pillars, and curvature of the bottom surface of the droplets were changed with respect to changes in the volume and concentration of the aqueous agar solution and the distance between the surface-bound pillars.
Electrochemical reactions of silver in the presence of chloride and bromide ions were examined using cyclic voltammetry (CV) and electrochemical quartz-crystal microbalance measurements. In the presence of chloride ions, repeated CV cycles caused AgCl to deposit on the electrode. In contrast, reduction of silver ions in the presence of bromide ions to form metallic silver was very slow, and AgBr was not deposited on the gold electrode.
Silica-supported silver exhibited high catalytic activity in the dehydration of glycerol: glycerol was dehydrated into hydroxyacetone with the selectivity higher than 86% at 91% conversion over Ag/SiO2 in H2 flow at 240 °C. Silver metal provides an active site and showed stable catalytic activity for the glycerol dehydration in H2 atmosphere, while the dehydration activity decreased in N2 atmosphere. The hydrogenation of hydroxyacetone into 1,2-propanediol and the decomposition to ethylene glycol did not proceed over silver.
An efficient method for the synthesis of tridentate PGeP– and PSnP–palladium complexes is developed. Structural analysis revealed that PSiP-ligand exerts the strongest trans influence and electron donation and that PGeP- and PSnP-ligands provide wider coordination sphere around the palladium. Preliminary studies demonstrated that both PGeP– and PSnP–palladium complexes work as an efficient catalyst for reductive aldol-type reaction, indicating promising utility in synthetic organic chemistry.
Hybrid hollow microspheres have been fabricated successfully via miniemulsion polymerization using the in situ formed and modified nanosilica particles as Pickering emulsifier. The hydrolysis and condensation reactions of tetraethoxysilane (TEOS) take place to form nanosilica particles which are then partially modified by oil-soluble 3-(trimethoxysilyl)propyl methacrylate (MPS) at the oil/water interface under basic conditions. After the miniemulsification process, Pickering miniemulsions were stabilized by the in situ nanosilica particles. Hybrid hollow microspheres are obtained with silica nanoparticles closely packed on the surface of polymer microspheres. The results showed that both the weight ratios of TEOS/styrene and MPS/TEOS have great effects on the production of stable Pickering emulsion and then the morphologies of the obtained hybrid microspheres.
A facile chromatographic method for purification of pinacol boronic esters has been developed. Impregnation of silica gel with boric acid was effective both for thin layer chromatography (TLC) and for flash column chromatography. Purification of a series of pinacol boronic esters was successful by suppressing loss of the compounds due to over-adsorption.
A new helix-directing salan ligand (R,R)-2 with the (1R,2R)-diaminocyclohexyl backbone and benz[a]anthryl sidearms was synthesized by borohydride reduction of the corresponding salen ligand. Formylation and reduction of (R,R)-2 yielded the N-Me counterpart, (R,R)-3. Complexation of these flexible ligands to TiCl4 produced the [TiCl2(salan)] complexes (R,R)-4 and (R,R)-5, which were characterized by NMR, IR, and HRMS techniques. The complexes were tested as catalysts for the asymmetric sulfoxidation of thioanisole with cumene hydroperoxide and hydrogen peroxide as the oxidants. Modest selectivity was observed, with the N-H salan complex showing somewhat better chiral induction.