The sol-gel reaction of tetraethoxysilane was performed in the presence of a polyester bearing a diacylhydrazine moiety to prepare an organic-inorganic hybrid, which was oxidatively degraded at room temperature to yield a nanoporous silica gel. When alkoxysilyl groups were introduced to the template polymer side chain, nanoporous silica gel functionalized with carboxylic acid was obtained.
We have successfully synthesized a novel chiral AB block copolyacetylene consisting of a dynamic cis-transoidal racemic helical sequence and a static cis-cisoidal one-handed helical sequence by using a three step procedure, that is, synthesis of an achiral block copolymer by living polymerization of OH-protected monomers, deprotection of the resulting polymer, and selective chiral induction to that of the sequence.
A rhodium-catalyzed cyclization reaction of 4-acyl-1-sulfonyl-1,2,3-triazoles possessing a phenyl ring is reported. Generated acceptor/acceptor carbenoids undergo cyclization by reacting either with a phenyl ring through electrophilic aromatic substitution or with a benzylic C–H bond through insertion depending on the length of the carbon chain.
Morphology is one of key factors to improve performance of organic photovoltaics, and further understanding is required. Conductive atomic force microscopy, C-AFM, is an experimental technique that can reveal morphologies in high resolution, but provides three-dimensional information with difficulty. In this study, dynamic Monte Carlo method is employed to simulate C-AFM of morphologies, which agrees with experiments. Simulation will help to predict three-dimensional morphologies from experimental data.
In this manuscript, we report an efficient heterogeneously catalyzed acceptorless dehydrogenative aromatization of cyclic amines under relatively mild conditions. In the presence of a supported catalyst Pd/LDH (LDH = layered double hydroxide), various kinds of structurally diverse cyclic amines including piperidines, tetrahydro(iso)quinolines, and indolines could be converted into the corresponding heteroarenes. Pd/LDH could be reused several times though its catalytic activity gradually declined due to the increase in the palladium particle size.
Ordered mesoporous carbon CMK-1 with partially graphitized domains was prepared from acenaphthene in Ni-loaded MCM-48, which showed an extremely high electric double-layer capacitance of 13.6 µF cm−2 using the ionic liquid, EMI-TFSI, as the electrolyte, caused by electronic adsorption of electrolyte ions on the edge planes of the graphitic domains.
Butadiene polymerization using a series of PNP-pincer ligated iron(II) complexes 1–3 as a catalyst was investigated. To see electronic effects, complex 3, bearing electron-donating amino group on pyridine ring, was newly synthesized. All the complexes promoted butadiene polymerization at room temperature upon activation by methylaluminoxane (MAO) to give high molecular weight polymer. Polybutadiene obtained from complex 2 contained 76% cis-1,4 sequence, which is the same level as the previous highest results using iron catalysts. Electron-donating substituents on the ligand reduced the ratio of 1,4-sequence in the obtained polymer, whereas steric effects on phosphorous atoms raised cis-specificity.
A thiophene flanked by strong electron-withdrawing octylrhodanines, T-ORH, was developed as a non-fullerene acceptor (NFA) for organic solar cells (OSCs), and to the best of our knowledge, this is the simplest NFA reported thus far. T-ORH was synthesized in two steps and exhibited sufficient energy-level offsets with poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]. The OSCs exhibited power conversion efficiencies of 1.25% with the open-circuit voltages of 0.9 V irrespective of additional treatment.
The 4-aryl substituted pyrazolate ligands, L1(Ph)H and L1(Naph)H, were synthesized by Suzuki–Miyaura cross-coupling and combined with metal sources to give cyclic trinuclear structures [AgL1(Ph)]3, [AuL1(Ph)]3, [AgL1(Naph)]3, and [AuL1(Naph)]3. The aryl group determined the crystal packing of these cyclic trinuclear complexes with the phenyl systems exhibiting stair type solid state structures and the naphthyl complexes exhibiting irregular structures with spaces occupied with some solvent molecules. These differences in solid-state structures were accompanied by differences in M–N stretching frequencies and temperature dependent photoluminescence.
Assemblies of gold nanorods capped with poly-diarylethene (DE) were chemically prepared in a solution. Plasmon assisted optical responses of the poly(DE) have been studied. Fluorescence from the open-form of DE was mostly quenched near 550 nm due to interband transition of gold, while fluorescence near 700 nm was slightly enhanced by the longitudinal plasmon resonance. Cycloreversion reaction of the gold nanorod-poly(DE) has been also studied, and it has been found that the reaction rate is enhanced by the plasmon excitation and increases nearly two-fold in the assembly. The magnitude of the enhancement is qualitatively consistent with the spatially and orientationally averaged value of the simulated optical field enhancements in the vicinity of the nanorod.
A facile method for forming both hydrophilic and hydrophobic surfaces is proposed here. Synthetic opal composed of mono-sized spheres of 250–290 nm was placed in contact with plastic substrates at 190 °C and then peeled off from the substrates at room temperature. The peeling process allowed a formation of hemisphere hole arrays of 200–230 nm on the substrate, which caused increased hydrophobicity. Because of partially remaining opal on the substrate, a hydrophilic and colorful surface was also obtained.
To construct an artificial viral capsid encapsulated short single-stranded DNA, a β-annulus peptide conjugated with ssDNA through a disulfide bond at the N-terminus (DNA-SS-β-Annulus) was synthesized. The DNA-SS-β-Annulus conjugate self-assembled into spherical structures ranging in the size of 36–60 nm. ssDNA was released from the capsids via the reduction of disulfide bonds.
Pd-catalyzed Suzuki-Miyaura cross-coupling reactions promoted by simple and commercial salicylaldehyde-based ligands were investigated. The effect of the ligands was evaluated and the reaction conditions were optimized. Moreover, the physical nature of the palladium was determined by TEM analysis and poison tests. It demonstrated that this catalytic system can be reused for ten consecutive runs and showed excellent activities toward aryl bromides with arylboronic acids at room temperature in air.
Herein, we present a method for controlling the surface properties of a substrate through exposure of the catechol group by acid stimulation. The results showed that the wettability and adhesion properties of the surface of the substrate can be controlled by acid treatment or UV irradiation in the presence of a photoacid generator. These findings will provide new insights into the development of materials with controlled surface properties.
A supramolecular benzoylpyridinium-substituted cyclohexanediamine gelator with n-type redox properties was synthesized. The gelator formed a robust supramolecular network consisting of cyclohexanediamine units. In the organogel, the stable redox reactions of the benzoylpyridinium moieties led to a reversible charge/discharge at −1.05 V (vs. Fc/Fc+). A supramolecule-based rechargeable device was fabricated using TEMPO- and benzoylpyridinium-substituted gelators as the cathode and anode, respectively, giving rise to a flexible, transparent, and even self-healable battery.
In this study, the efficiency of tail-to-tail dimerization of Michael acceptors catalyzed by N-heterocyclic carbene has been significantly improved. By increasing the reaction temperature to 200 °C, turnover number (TON) values of 146 and 185 were achieved for the dimerization of n-butyl and allyl methacrylates, respectively. Glycidyl methacrylate also underwent the dimerization without ring-opening of the epoxy group. The polymer synthesis from the resulting dimers was also demonstrated through transesterification polycondensation and thiol-ene “click” polyaddition.
This study demonstrates that surface modification of a carbon-paper cathode by oxygen functional groups expands the potential region for the sustained discharge of non-aqueous Li-O2 batteries. Expansion of the potential region is considered to be due to a decrease in the over-potential for the oxygen reduction reaction and modification of the electrochemical adsorption isotherm of LiO2, which is an important adsorbed intermediate that determines the discharge capacity.
Two novel lead ion imprinted adsorbents were prepared based on tridentate functionalized mesoporous silica material. Adsorption sites and behaviors were investigated. The adsorbent BPMA-Pb-IIMS possessed maximum adsorption capacity of 202 mg g−1 in 20 min at room temperature, excellent stability and could be reused 8 times. BPMA-Pb-IIMS was applied in the adsorption and removal of Pb2+ in real water samples.
The possible C-Cl bond activation transition states of five proposed mechanisms in CuI/N,N′-bis(2,4,6-trimethoxyphenyl)oxalamide (BTMPO) catalyzed coupling reaction of chlorobenzene and benzylamine (W. Zhou, M. Fan, J. Yin, Y. Jiang, D. Ma, J. Am. Chem. Soc. 2015, 137, 11942) are compared by DFT calculations, and the favored oxidative addition/reductive elimination mechanism is studied in detail, showing that the rate-determining step is the oxidative addition step in which the auxiliary ligand contains BTMPO only, and then a concerted substitution of the chloride anion on the Cu(III) metal center by deprotonated benzylamine occurs. A general mechanism of Ullmann-type coupling reaction of (hetero)aryl chlorides is proposed according to these calculations.
Electrochemical ozone generation at an easily prepared platinum-modified titanium electrode was investigated and compared with that at boron-doped diamond (BDD) and Pt electrodes. The Pt/Ti electrode was prepared through our original method, the multiple electrostrike method. The ozone generation ability of the Pt/Ti electrode was much higher than those of BDD and Pt electrodes. This research is expected to contribute to the development of practical electrodes for inexpensive and effective ozone generators.
Thermo-responsive polymer-coated polystyrene particles with a diameter of 84 µm (PNIPAM@PS) were prepared. The hydrophobicity of the surface of the PNIPAM@PS can be controlled by changing the temperature of the environment. We studied the effect of temperature and salt concentration for electrostatic formation of liquid marbles prepared using PNIPAM@PS.
An efficient benzene ring construction method using oxadiazinones as a platform molecule has been developed. Sequential reactions of oxadiazinones with cycloalkynes and arynes afforded partially reduced polyaromatics. This method enables facile preparation of various unsymmetrical doubly-ring-fused benzene derivatives including multisubstituted tetrahydroanthracenes and anthracenes.
Using a sinusoidal motion friction evaluation system, friction phenomena on various substrates were studied. It was found that the addition of silica nanoparticles increased the kinetic friction coefficient between agar gels, but not between gel and glass substrates. These results suggest that friction force between surfaces of agar gel can be controlled by addition of silica nanoparticles.
Au nanoshells have been synthesized at the liquid-liquid interface between primary ammonium-based ionic liquids and water. Ionic liquid-in-water emulsions, which are spontaneously formed on the water side of the interface, function as a template for the synthesis of Au nanoshells. Selective adsorption of the primary amine group on the Au surface plays an important role in the formation of Au nanoshells.
An acyl group derived-bipyridine ligand and Eu form 3:2 complexes. The structure and luminescence behaviour were evaluated, and we found an unexpected bi-nuclear complex system, which induces efficiently the luminescence of europium ion. This observation is discussed from experimental and theoretical viewpoints.
Polyethylene glycol (PEG)-grafted metal–organic polyhedra (MOPs) provided defect-free mixed-matrix membranes via the solution-cast process. Compared to the neat PEG-based membranes, the membranes prepared with PEG-grafted MOPs showed enhanced gas permeation for carbon dioxide, while maintaining selectively toward methane, which could be ascribed to the distinctive self-organized nanostructure and core-shell architecture of PEG-grafted MOPs.
Correlation between strength in an external magnetic field and spectral width of solid-state sulfur-33 nuclear magnetic resonance (NMR) spectra in an organosulfur compound, whose quadrupolar coupling constant is more than 40 MHz, is discussed. As an alternative method to higher magnetic field NMR, WURST-QCPMG technique at lower magnetic field is proposed and the result is presented.
In this letter, zirconium carbide (ZrC) nanoparticles have been synthesized through the reaction of zirconium dioxide and waste polyethylene (PE) at 700 °C, in which metallic lithium acted as the reductant. X-ray powder diffraction patterns indicate that the obtained sample is face-centered cubic ZrC. As waste polyethylene is substituted by waste polytetrafluoroethylene (PTFE) and waste polyvinyl chloride (PVC), ZrC can also be produced through similar processes. Therefore, it is a general way for preparation of ZrC nanoparticles. Meantime, this strategy provides a novel way for reuse of waste plastic.
We demonstrate a modulation of whispering gallery mode (WGM) photoluminescence (PL) from self-assembled microspheres of fluorene-terpyridine alternating copolymer by protonation/deprotonation. Upon subsequent addition of acid and base, the PL color of the microspheres can be modulated between blue and green repeatedly, accompanying the shift of the WGM PL peaks.
Preparation of 2-halo-3-substituted-thiophene bearing a cyclic oligosiloxane moiety in the side chain was carried out and subjected to nickel(II)-catalyzed deprotonative polymerization to give the corresponding polythiophene, which was found to be highly soluble in various organic solvents particularly in hexanes. Treatment of the thin film of the obtained polythiophene with acidic vapor resulted in cross linking of the cyclic siloxane moiety through ring opening. Accompanying doping of the polythiophene main chain on the polymer film indicated improved conductivity with remarkably drastic change in before/after acidic treatment.