We review novel thermodynamic properties of κ-(BEDT-TTF)₂Cu₂(CN)₃ and EtMe₃Sb[Pd(dmit)₂]₂, where BEDT-TTF stands for bisethylenedithiotetrathiafulvalene and dmit stands for 1,3-dithiole-2-thione-4,5-dithiolate unveiled via single-crystal calorimetry. These compounds are organic dimer-based Mott insulators with a two-dimensional triangular lattice, where electron correlations produce localized radical spins on each molecular dimer. Néel-type magnetic orderings are prohibited by geometric frustrations and strong quantum mechanical fluctuations. The spin orientation of localized π electron fluctuates like a liquid even at zero energy, and the so-called spin-liquid (SL) ground state appears in them. We have performed heat capacity measurements down to extremely low temperatures and observed that the low-temperature heat capacities show a gapless character, evidenced by the finite electronic heat capacity coefficient, γ. Although the charge-transport properties of these compounds are insulating, the thermodynamic parameters, which reflect the low-energy excitations from the liquid ground state, resemble those of typical metallic compounds with Fermi-liquid characteristics. The magnitude of the γ was scaled with the magnetic susceptibility extrapolated down to T = 0. The realization of the unusual magnetic state coupled with the charge degree of freedom is suggested by several other experiments in addition to the heat capacity measurements. Herein we review thermodynamic discussions based on the experiments reported up to now to clarify the novelty of this magnetic ground state.  

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Oligosaccharides play pivotal roles in various molecular recognition events on cell surfaces and in intracellular environments. Although information about the three-dimensional structure of oligosaccharides is crucial for understanding the mechanisms underlying their biological functions and for designing drugs targeting carbohydrate recognition systems, their inherent flexibility hampers detailed conformational analysis. NMR spectroscopy has immense potential for providing atomic details of oligosaccharide structures in solution as well as in complexes with other biomolecules. However, the traditional NMR approach based on local conformational information provided by the nuclear Overhauser effect (NOE) is often precluded by insufficient information about long interatomic distances and hydrogen bonds involving hydroxy groups. To address these issues, new NMR techniques have recently been developed, exploiting the effects of introduced paramagnetic probes and stable isotopes to target oligosaccharides. Lanthanoid tagging and the spin labeling of oligosaccharides induce paramagnetic effects such as pseudocontact shift and paramagnetic relaxation enhancement, offering NOE-independent sources of long-distance information. Deuterium-induced isotope shifts of neighboring ¹³C resonances provide an experimental tool for the identification of hydrogen bonds involving oligosaccharide hydroxy groups. The uniform and position-selective ¹³C enrichment of oligosaccharides can be achieved by metabolic labeling using genetically engineered yeast cells. Furthermore, small ganglioside-embedding bicelles have been used for detailed NMR analyses of intermolecular interactions involving glycolipids in membrane environments. These NMR approaches, in conjunction with computational simulation, have opened up new vistas for the analysis of oligosaccharide conformations and interactions at atomic level.  

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To investigate the temperature dependency of gibbsite and boehmite formation, the Gibbs free energy change (ΔG) was calculated at different temperatures. Calculated Gibbs free energy shows a positive value at 323 K, and gibbsite formation is preferred. On the other hand, it shows a negative ΔG value at 371 K, and boehmite formation is preferred. These predictions were characterized by transmittance electron microscopy and X-ray diffraction.

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Cu–Ag bimetallic nanoparticles loaded on reduced graphene oxide nanocomposites (Cu–Ag/rGO NCs) were obtained through a facile chemical reduction method. The resulting Cu–Ag/rGO NCs exhibited good catalytic activity in reducing H₂O₂, with a fast amperometric response, i.e., less than 2 s. The linear detection range was estimated to be from 50 µM to 3.5 mM (R = 0.9983), and the detection limit was estimated to be 12 µM at S/N = 3.

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New fluorohydrogenate salts based on azoniaspiro-type cations (AS[x.y]⁺, x and y denote the number of methylene carbon atoms in each cyclic group) have been synthesized and characterized. Effects of the number of rings and carbon number on physical and structural properties are discussed. Introduction of oxygen atoms in the ring structure is also conducted.

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A facile microwave-assisted synthetic route has been successfully developed to prepare CuO microspheres in the presence of poly(vinylpyrrolidone) (PVP). The products were characterized by X-ray diffraction and scanning electron microscopy. The effects of microwave irradiation time and surfactant on the morphologies of the resulting products were investigated. Gas-sensing tests demonstrated that the sensors based on the CuO microspheres show higher responses to ethanol and methanol.

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Dewetting behaviors of sub-50-nm-thick ultraviolet-curable resin films comprising hydroxy-containing (meth)acrylate monomers on modified Au-plated substrates were investigated by fluorescence microscopy. Hydroxy-terminated alkanethiol-adsorbed monolayers on Au surfaces suppressed dewetting of the thin spin-coated films and allowed the fabrication of 50-nm-line-width Au split-ring resonator (SRR) arrays by ultraviolet nanoimprint lithography.

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Steady-state photolysis of an acetonitrile solution of triarylphosphine (Ar₃P) was carried out using a xenon lamp. The major products resulting from photolysis under deoxygenated conditions and under air were diaryl(cyanomethyl)phosphine Ar₂PCH₂CN and triarylphosphine oxide Ar₃P=O, respectively. Intrinsically, Ar₃P in the excited state undergoes homolytic cleavage of a P–C bond; however, electron transfer to O₂ is predominant under air. Reactivity of Ar₃P in the excited state is readily controlled by the choice of atmosphere used in the reaction.

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The electronic and structural properties of a phosphorus-terminated structure of Ni₂P(0001) surface (Ni₃PP) are investigated by density functional theory (DFT) calculations. Phosphorus adsorption largely stabilizes the Ni₂P(0001) surface by creating Ni–P bonds on the Ni trimer. Atomic hydrogen can adsorb on the topmost P site although its adsorption energy is much lower than its adsorption energy on the Ni trimer site of the Ni₃P₂ surface. Our results suggest that the Ni trimer is the key factor for high catalytic activity.

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A chitosan-based adsorbent functionalized by polyethyleneimine has been prepared using a freeze-drying method. The adsorbent showed a CO₂ adsorption capacity of 2.38 mmol g⁻¹ at 333 K and 15 kPa of CO₂. Furthermore, the adsorption capacity increased up to 3.61 mmol g⁻¹ in the presence of water vapor. This biomass-derived material is, therefore, a potential low-cost and efficient adsorbent for CO₂.

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Using highly negatively charged Keggin polyoxometalates (POMs), [α-XW₁₂O₄₀]⁵⁻ (X = Al and B), novel intercluster compounds composed of a tetrakis{triphenylphosphanegold(I)}oxonium cation and an α-Keggin POM linked by three monomeric triphenylphosphanegold(I) units were prepared. A single peak was observed in the solution ³¹P{¹H} NMR for these clusters, which is consistent with rapid exchange of the phosphanegold(I) units in the tetra{phosphanegold(I)}oxonium cluster cation with the three monomeric phosphanegold(I) species linked to the POM. Importantly, these compounds may be relevant transition states or intermediates in POM-mediated tetra{phosphanegold(I)}oxonium cluster formation.

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Photoisomerization quantum yields (Φ_E–Z) of phenylazo-substituted imidazolium cations, which are counterparts of recently developed photochromic ionic liquids, were measured under S₁(n, π*) excitation. The Φ_E–Z values are lower in imidazolium-type ionic liquids than those in conventional solvents and in tert-alkylammonium-type ionic liquids. This observation was argued based on solute–solvent complex formation at imidazolium rings.

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L-Proline moieties, which serve as organocatalysts, were tethered on block copolymers that consisted of thermoresponsive poly(N-isopropylacrylamide) and PEG-grafted polyacrylate blocks. The copolymer dissolved in water at temperatures below the LCST (25 °C), whereas they formed micelles at temperatures above the LCST (50 °C). Aldol reactions between an arylaldehyde and a ketone were conducted in this aqueous solution. The aldol products were obtained in high yield with high diastereo- and enantioselectivity (96% ee). The catalyst solution could be reused up to three times.

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A new catalytic system for the hydrogen-transfer oxidation of alcohols catalyzed by iridium complexes bearing a functional pyridonate ligand has been developed. By using isopropenyl acetate as a hydrogen acceptor, a variety of primary alcohols were efficiently converted to the corresponding aldehydes in moderate to excellent yields.

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The title cyclic compounds, synthesized by cross-coupling reactions, have nonplanar frameworks, as revealed by X-ray analysis and DFT calculations. The barrier to exchange between the nonplanar structures of the mesityl derivative was determined to be 34 kJ mol⁻¹ by a dynamic NMR method.

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A novel route was developed to synthesize amorphous carbon nanotubes (a-CNTs) from organic carbon using V₂O₅ and glucose solution as the starting materials. The annealing process can stabilize organic carbon shells, leading to the successful formation of a-CNTs, which is the crucial step for preparing a-CNTs. The as-obtained a-CNTs have uniform diameters with outer diameter ranging from 150 to 250 nm and inner diameter about 30 nm on average, and their length is up to several micrometers. The carbon in the as-synthesized a-CNTs is completely amorphous, and the as-prepared a-CNTs are a kind of hydrogenated a-CNTs containing both sp³- and sp² carbons. Furthermore, the as-prepared a-CNTs have good thermal stability and oxidation resistance below 305 °C in air.

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A fibrous nanosized catalyst with TEMPO supported on silica nanospheres was synthesized and used in the selective oxidation of alcohols into the corresponding aldehydes or ketones. The fibrous morphologies of the catalyst allowed easy accessibility between the substrate and the catalyst, and thus, improved reaction efficiency was obtained. A pseudo-homogeneous system was formed during the reaction process, with easy recovery of the catalyst through filtration.

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One of six 2-alkylamino-4,6-dimethylnicotinamides afforded a conglomerate, and subsequent X-ray crystallographic analysis revealed that the compound crystallized in the monoclinic system, the space group P2₁. Crystallization of the racemic nicotinamide from the melt led to the chiral breaking of symmetry from 83 to 92% ee. This amide exhibited considerably stable axial chirality (ΔG^‡: 22.4–23.5 kcal mol⁻¹ at 20 °C) due to rotationally restricted scaffolds for the C–C(=O) bond.

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Zwitterionic fluorescent polymers (ZFPs) are developed by using poly(sulfobetaine methacrylate), NIPAAm, and BODIPY fluorophores to examine the patterning characteristics based on mussel-inspired surface modification. Water contact angle measurements of ZFP show changes in the angle upon altering the pH. The ZFP was developed on PDMS stamps and imprinted onto a glass substrate, which provided a green fluorescent micropattern under a fluorescence microscope, making the ZFP a powerful tool for development of a useful patterned substrate for various applications.

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We have successfully prepared nanoribbons of blue potassium molybdenum bronze (K_0.3MoO₃) from hydrogen molybdenum bronze (H_0.3MoO₃) by using crystallite splitting induced by solid-phase transformation and subsequent selective growth under hydrothermal conditions. The obtained nanoribbons were single crystals with a size of ca. 100 µm × 100 nm × 10 nm, well-elongated to the crystal b axis that corresponds to the conduction direction as a quasi-one-dimensional metal. A simple deaeration procedure necessary for preparing a single phase of blue potassium bronze is also given.

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Silicone polymer films in which plate-like chiral and achiral crystals of salicylidenephenylethylamines were aligned by a magnetic field were prepared. The polymer films exhibited reversible photomechanical bending upon alternate irradiation with UV and visible light.

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The possibility of an organometal halide perovskite, CH₃NH₃PbBr₃, was investigated as a cosensitizer to a Ru-complex dye and an alkoxysilylcoumarin dye in dye-sensitized solar cells. The perovskite was found to work as the cosensitizer effectively, and the light-to-electric energy conversion efficiencies of the cells were improved more than 10% by the cosensitization under the present test conditions.

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This paper describes a simple and efficient protocol for the N-alkylation of arylamines with benzyl alcohols using tantalum(V) fluoride as the catalyst.

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56π-Electron fullerene derivatives possessing both a hydrogen and an electron-withdrawing cyano addend were synthesized by the reaction of 58π-electron fullerenes with NaCN and subsequent protonation and used as acceptors in bulk heterojunction solar cells containing a low-band-gap polymer donor. The device showed power conversion efficiency of 5.2%.

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A continuous fluorometric assay system based on melittin and a pyrene derivative 1 for trypsin and its inhibitor screening is successfully developed by taking advantage of the noncovalent-binding-induced pyrene excimer. The 1–melittin assembly and its disassembly after further addition of trypsin are confirmed by the fluorescence changes at 475 nm. Such a system can be applied to other proteases of melittin, and essentially, the concept based on the noncovalent-binding-induced continuous fluorometric assay can be extended to other biochemical analyses.

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The dimerization reactions of 2-bromo-3,5,6-trimethyl-1,4-benzoquinone have been examined. 2,2′-Dimeric benzoquinone was prepared via a Stille-type homocoupling, whereas an oxepin was formed by the treatment of the title quinone with hexamethylditin, CuI, and (±)-BINAP in DMF. Two dimerization reactions involving a hetero Diels–Alder reaction between quinones and quinone methides were also observed.

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Stimuli-responsive unimer nanoparticles (NPs) composed of hydrophobized poly(γ-glutamic acid) were successfully prepared by a combination of hydrophobic interactions and disulfide bonds. The formation of hydrophobic associations and the existence of disulfide bonds were confirmed by UV spectroscopy and by treatment with dithiothreitol, respectively. Moreover, the release of hydrophobic drugs in response to a reducing agent was observed when compared to nonstimulus unimer NPs. These 10 nm-sized unimer NPs will be useful as reduction-responsive carriers.

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A unique photoinduced change in the molecular ordering of a photochromic diarylethene derivative having amide groups was investigated at the liquid/highly oriented pyrolytic graphite (HOPG) interface by scanning tunneling microscopy (STM). Ordering of the diarylethene was stabilized by the hydrogen-bonded network of amide groups. The open- and the closed isomers formed characteristic stripe-patterned orderings; a different hydrogen-bonding network was formed in each case. In situ UV irradiation resulted in the exclusive formation of a third molecular ordering γ that is composed of the photoirreversible annulated isomer. No photoisomerized molecule was detected in the 2-D orderings, i.e., the open-ring isomer in the ordering of the closed-ring isomer and vice versa, despite the similarity in their molecular structures.

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An interpenetrating polymer network (IPN) of poly(N-vinylacetamide) (PNVA) and poly(2-hydroxylethyl methacrylate) (HEMA) was designed to deactivate agricultural chemicals. The imprinting effect of PNVA hydrogel preparation is discussed, as compared to PNVA single hydrogels and nonimprinted IPNs in the methamidophos adsorption experiments.

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An iron(III) complex [Fe(qsal)₂]₂NP·CH₃OH (1) (Hqsal: N-(8-quinolyl)salicylaldimine, and NP: nitroprusside) was synthesized and characterized by X-ray structure analysis, temperature-dependent magnetic susceptibility, and Mössbauer spectroscopy. The structures of 1 at 100 and 300 K were determined. X-ray crystallographic data revealed that the compound 1 was constructed by two [Fe(qsal)₂]⁺ sites in the low-spin and high-spin states and a nitroprusside site at 100 K, and two [Fe(qsal)₂]⁺ sites in the high-spin state and a nitroprusside site at 300 K. One site [Fe(qsal)₂]⁺ in iron(III) complex exhibited spin-crossover behavior and LIESST effect.

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Polyimide (PI) aerogels containing rigid-rod biphenyl, benzimidazole, and triphenylpyridine moieties have been developed. The flexible PI aerogels exhibited excellent thermal stability with glass-transition temperatures (T_g) higher than 350 °C. Initial porous structures in the PI aerogels could be maintained even after isothermal aging at 300 °C for 24 h in nitrogen. Furthermore, the weight losses of the aerogels after isothermal aging at 300 and 400 °C for 24 h in nitrogen were below 5 and 10 wt %, respectively.

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Derivatives of a new bis-fused TTF analogue 2 composed of TTF and 2-(xanthen-9-ylidene)-1,3-dithiole have been synthesized. Cyclic voltammograms of 2 are composed of three pairs of redox waves, of which the third redox wave corresponds to a two-electron-transfer process. X-ray structure analysis of the ReO₄⁻ salt of bis(methylthio)-2 [(2b)ReO₄(DCE)_0.5] revealed that the 2b molecules form a dimerized one-dimensional stack.

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Carboxylic acids were applied to an indium triiodide-catalyzed reductive aldol reaction and a reductive cyanation in order to produce aldol adducts and cyanohydrins, respectively, in which the separate addition of two kinds of hydrosilanes was crucial in combination with either ketene silyl acetals or silyl cyanides.

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To modulate and evaluate the strength of noncovalent interactions experimentally, mononuclear ruthenium aqua complexes ([Ru(dnp)(OH₂)L₂]²⁺: dnp: 2,6-di(1,8-naphthyridin-2-yl)pyridine, L = pyridine or triphenylphosphine) that are capable of forming multiple intramolecular hydrogen bonds have been prepared. In both solution and the solid state, the intramolecular hydrogen-bonding strength in these complexes can be regulated by the axial ligand (L).

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Derivatives of tris-fused TTF donors 3 extended with cyclohexene-1,4-diylidene were synthesized. Cyclic voltammetry revealed that the tetrakis(hexylthio)-3 (3c) exhibited three stages of a two-electron redox process to afford the hexacation. The rechargeable battery incorporating tetrakis(methylsulfanyl)-3 (3b) as the positive electrode material exhibited a high cycle performance in spite of utilizing the highest oxidation state of +6.

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Chemical stabilities of secondary alkanolamine substrates in CO₂ solvents under stripping conditions and generation pathways of thermal degradation products have been studied. The two products generated in each amine solution have been proven to be oxazolidone and dimer of each amine. The thermal degradation of secondary alkanolamine proceeds in two steps as consecutive reactions. The carbamate compound, which is CO₂-absorbing amine, cyclodehydrates to generate oxazolidone, and the oxazolidone further reacts with another amine to generate dimer through decarbonation condensation.

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Novel environmentally friendly inorganic blue pigments based on garnet-type (Ca_1−xEu_x)₃Sc₂Si₃O_12+δ, were successfully synthesized, and their color properties were characterized. Among these samples, (Ca_0.94Eu_0.06)₃Sc₂Si₃O_12+δ pigment calcined at 1648 K for 6 h showed the most brilliant blue color. The −b* value corresponding to blue chromaticity of the pigment was −33.8, which exceeded that of a commercially available iron(III) hexacyanoferrate(II) pigment (Prussian blue, b* = −15.6). Since the present (Ca_0.94Eu_0.06)₃Sc₂Si₃O_12+δ pigment is composed of only nontoxic and safe elements (Ca, Eu, Sc, Si, and O), it could be an effective alternative to the conventional blue materials.

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A mixed-valence Ru(II)–Ru(III) complex was used to catalyze the skeletal reorganization of 1,6-enynes, leading to the production of 1-vinylcyclopentene derivatives. The reaction proceeded optimally in an atmosphere of O₂ or CO. The presence of an alkyl group at the internal olefinic carbon in the starting enyne resulted in an increase in product yield compared to that bearing no substituent on the olefin moiety.

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It is possible to switch between the different aggregation phenomena of deoxyribonucleic acid (DNA)-conjugated poly(N-isopropylacrylamide) (PNIPAM) by controlling the balance of DNA charges and flexibility. The shift in the balance between DNA charges and flexibility occurs by changing the salt concentration in polymer solutions and the DNA fraction in polymer chains. Single-stranded DNA (ssDNA)-conjugated PNIPAM was more aggregated than double-stranded (dsDNA) when DNA charges are predominant. In contrast, dsDNA-conjugated PNIPAM was more aggregated than ssDNA when flexibility was predominant.

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Novel dihedral-angle-controlled 2,2′-bithiophenes with terminal ferrocenyl groups have been designed and prepared. The electrochemical and spectroscopic properties indicated that the interaction between the terminal ferrocene moieties was distinctly affected by the twist in the π-conjugated system.

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