Selones, since their first report in 1963, have attracted significant interest with respect to their bonding, structure and more importantly as an ancillary ligand for complexation with various metals. Starting as an analogue of N-heterocyclic carbene (NHC), selones are considered as promising molecules in chemistry with numerous applications in various important processes. Herein, a brief overview of selone, its genesis and relevance in contemporary chemistry is given, particularly focusing on its syntheses, reactivity and applications.
The O–O bond cleavage of peroxide ligands such as hydroperoxide and alkylperoxide within metalloenzymes has been extensively investigated because this process constitutes the key step of dioxygen activation and cellular respiration in all forms of aerobic organisms. Herein, we have provided mechanistic insights into the O–O bond cleavage of iron-(hydro/alkyl)peroxo complexes that was promoted by endogenous and exogenous factors such as spin-state, axial ligand, and electron donors. It has been shown that these factors can effectively direct the O–O bond cleaving pathways (e.g., Fe–O bond cleavage vs O–O bond cleavage or homolysis vs heterolysis). These results support that the peroxide bond cleavage process might proceed via diverse pathways under biological reaction conditions.
Polymer nanofibers with controlled diameters were formed by continuous spinning using ordered anodic porous alumina as a spinneret. The diameter of the polymer nanofibers could be controlled by changing the hole size in the porous alumina membrane. In addition, the diameter of the obtained polymer nanofibers could be reduced by mechanical stretching in water at 80 °C. The obtained polymer nanofibers are expected to be used for various applications that require nanofibers with uniform diameters.
Carbon-coated NiO/reduced graphene oxide (NiO/rGO) composites with NiO nanoparticles (∼5 nm) homogeneously distributed and carbon skeletons on the surface were constructed in this work. Graphene oxide (GO) provided abundant surface nucleation sites benefiting nanosized NiO nanoparticle formation and a conductive carbon skeleton was prepared simply by carbonization of cost-effective glucose. The carbon-coated NiO/rGO composites show enhanced electrochemical performance and exhibited 1230, 936 and 880 F g−1 at 1.0, 2.0 and 4.0 A g−1.
The first method for decarbonylative direct arylation using acyl fluorides is reported. This reaction proceeds, only when acyl fluorides are used, and other acyl halides cannot be used. The reaction can be applied to the direct arylation of a variety of substrates, including xylene, quinoline, and benzothiophene.
Thin films of liquid crystalline polymethacrylates possessing an azobenzene and a cyanobiphenyl side chain exhibit a homeotropic and planar mesogen orientation, respectively. Here, we report a systematic study on the evaluations of collective orientation preference of the above hybrids changing the mesogen ratio obtained by random copolymerization. At intermediate polymerization ratios, both the in-plane and out-of-plane photoalignments were efficiently achieved by light irradiation.
Here we report the synthesis and electrocatalytic properties of polymer films containing nitrogen and iron. The films were prepared by calcination of polydopamine, polyethyleneimine and iron. The composite films were self-assembled at the air/water interface, and exhibited higher activity for the oxygen reduction reaction than glassy carbon or calcined polydopamine films. These results suggest that such calcined composite films have potential applications as cathodes in polymer electrolyte fuel cells.
A new protocol for the production of deuterium gas from easily-obtainable deuterated methanol and deuterium oxide has been developed. The reaction of deuterated methanol and deuterium oxide in the presence of an iridium catalyst bearing a functional bipyridonate ligand and sodium hydroxide under reflux for 48 hours gave deuterium gas in 63% yield. Deuteration reactions of unsaturated compounds and bromo-substituted aromatic compounds using the generated deuterium gas in the presence of palladium/charcoal catalyst were also investigated.
We designed and synthesized 2-[(2-amino-5-nitro-phenylamino)-methyl]-5-diethylamino-phenol (L1) as a stable and highly sensitive hypochlorite probe. L1 may be used in both colorimetric and fluorometric applications, as well as in paper-strip detection for selective hypochlorite ion sensing. In this study, we successfully applied L1 to the imaging of local hypochlorite generation in the endosomes, including phagosomes, of living cells. Thus, L1 is an appropriate probe for the detection and visualization of hypochlorite ions in vitro and in living cells.
In this work, a novel biosensor was fabricated with nanocrystalline dysprosium oxide (Dy2O3) - graphene oxide (GO) as the carrier to immobilize hemoglobin (Hb) for the detection of hydrogen peroxide (H2O2). Dy2O3 and GO were firstly prepared via hydrothermal method and the traditional Hummers method respectively. The obtained Dy2O3 was characterized by field emission scanning electron microscopy (SEM) and X-ray diffraction (XRD). The GO, Dy2O3 and Hb composites were modified on the surface of the bare glassy carbon electrode (GCE) to construct the biosensor. The whole fabrication process and the electrochemical properties of the fabricated biosensor were fully studied via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). By utilization of the synergistic effect between the electrical properties of Dy2O3 and the good conductivity of GO, the prepared biosensor provided a biocompatible microenvironment for Hb to perform direct electron transfer at the modified electrode, and exhibited excellent electrocatalytic reduction of H2O2. The fabricated biosensor showed a good linear relationship with H2O2 in the range of 5–300 µM and the square of correlation coefficient R2 = 0.984. This biosensor has the advantages of wide detection range, good stability and reproducibility, and strong anti-interference ability. Satisfied performance was obtained when applied for the detection of practical sample.
A hybrid of oxygen-defect-abundant Co3O4−x nanoparticles and graphene was successfully synthesized by a simple one-step laser irradiation method, and N atoms were introduced into the graphene by subsequent hydrothermal treatment. The Co3O4−x/NG exhibits remarkably enhanced OER and ORR catalytic performance compared to Co3O4/NG and a mixture of Co3O4−x and NG, which could be attributed to the oxygen vacancies and the synergistic effect of Co-N-C species. This study can offer a new way for the design and synthesis of OER/ORR bi-functional electrocatalyst.
Treatment of fac-[Rh(apt)3] (apt = 3-aminopropanethiolate) with [Cu(CH3CN)4]+ in a 2:3 ratio in water gave a CuI3RhIII2 pentanuclear complex ([1apt]3+), in which two octahedral fac-[Rh(apt)3] units are linked by three linear CuI ions through sulfur bridges. Complex [1apt]3+ was oxidized to produce a CuICuIIRhIII2 tetranuclear complex, in which two fac-[Rh(apt)3] units are linked by linear CuI and square-planar CuII ions. The structure and properties of [1apt]3+ were compared with those of the corresponding CuI3RhIII2 complex with 2-aminoethanethiolate.
We report an efficient luminescent molecule exhibiting thermally activated delayed fluorescence with a long-delayed fluorescence lifetime of 0.8 ms. Although the reverse intersystem crossing rate constant is small at 2.1 × 103 s−1, the molecule shows a high photoluminescence quantum yield of 89 ± 2%, indicating the suppression of nonradiative decay from the triplet state.
A database for 240 types of lithium-ion conducting solid polymer electrolytes was newly constructed and analyzed by machine learning. Despite the complexity of the polymer composites as electrolytes, accurate prediction was achieved by the appropriate learning model. Inspired by the analyses, poly(glycidyl ether) derivatives were synthesized to yield higher conductivity. Screening of single-ion conducting polymers with de novo design (>15000 candidates) was also conducted based on the established database.
A conjugated macrocyclic molecule incorporating two m-diethynylene-phenylene-bridged quinoline moieties was synthesized via isocyanide-acetylene cyclization and Pd/Cu-catalyzed Sonogashira cross-coupling reactions. X-ray crystal analysis and DFT calculation revealed that the new macrocyclic molecule has a rigid parallelogram structure. The photophysical and electrochemical properties were studied by several spectral analyses, and were rationalized by DFT calculations.
Kawai et al. reported the crystal structure of a dispirobis(10-methylacridan) derivative that contains a C–C single bond over 1.77 Å long. In this Letter, quantum chemical calculations of the compound and its derivatives for the isolated and the crystal systems were performed. These calculations demonstrated that the intramolecular and intermolecular dispersion interactions, as well as the crystal packing effect, are important to realize such an ultralong C–C bond length.
Photodissociation spectra near the Soret region were acquired for hydrated myoglobin (Mb) ions isolated in the gas phase. The spectra had a large red shift relative to that from an acidic aqueous solution, which indicated a significant structural change from a pH-denatured state to the isolated native structure. The pH denaturation of Mb was therefore strongly affected by surrounding water molecules.
Nanometer-sized PbI2 particles were deposited over mesoporous TiO2 film by spin-coating and tested as a photosensitizer. The as-prepared PbI2-sensitized solar cell gave overall power conversion efficiency of 1.41% which was almost four times better than a comparable CdS quantum dot sensitizer prepared by the successive ionic layer adsorption and reaction process.
A nondirected dehydrogenative direct alkenylation of simple aromatic compounds with alkenes under rhodium catalysis is described. The site-selectivity is dominantly dictated by the steric bulkiness around the targeted C–H bond. The reaction efficiency was largely contingent on the identity of copper(II) carboxylate as oxidant, and considerable improvement of the productivity was achieved by the addition of a sulfate salt.
Several polyamide composites were obtained by condensation reaction of tetracarboxy cobalt phthalocyanine with several diamino-functionalized monomers. The obtained composites were pyrolyzed at 900 °C in a hydrogen stream to afford several platinum-alternative oxygen reduction catalysts for polymer electrolyte fuel cells containing different nitrogen contents and the oxygen reduction activity (ORA) was investigated. It was revealed that the ORA was related not to the nitrogen content but to the heat resistance of the precursors of the catalysts.
A new water-stable magnesium (Mg) coordination polymer (Mg(HPCD)(H2O)) with a two-dimensional structure was synthesized and structurally characterized, and its luminescence properties were studied. The high blue emission intensity and the available coordinating nature of Mg-CP make it useful as a luminescent sensor of Fe3+ ions.
The active oxygen species for ethylene epoxidation on Ag surfaces has been a long-standing issue. We conducted in situ observations of Ag(111) surfaces under exposure to ethylene and oxygen gases with near ambient pressure (NAP) X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. Combined results of these spectroscopies evidence that a carbonate species with a flat-lying configuration is formed on the Ag(111) surface at 370–500 K under exposure to the NAP gas mixture of ethylene and oxygen.
We succeeded in the synthesis of an anionic stannaferrocene by the reaction of a dilithiostannole with a Fe(III) reagent, which cannot be achieved by the use of cyclopentadienyl (Cp) and its related ligands. The Mössbauer spectroscopic analysis and quantum-chemical calculations indicate that the contribution of a resonance form arising from a Fe(I) and two stannole anion is the most plausible state. The cyclic voltammetry of the anionic ferrocene revealed a quasi-reversible oxidation wave at (Epa = −1.60, Epc = −1.40, E1/2 = −1.50 V vs Fc/Fc+), lower than that of the parent ferrocenide anion, owing to the introduction of the aromatic dianionic stannole ligands.
Cyclic tetramers of 10-alkylanthracene-1,8-diyl units were synthesized by Ni-mediated coupling of the corresponding 1,8-dibromo precursors as new cycloarenes. X-ray analysis and DFT calculations revealed that these molecules had a box-shaped framework with dihedral angles between adjacent anthracene planes of ca. 70° and 110°. The macrocyclic framework had high conformational mobility compared with their analogs having ethynylene linkers. The UV-vis and fluorescence spectra indicated that the π-conjugation is not extended in the cyclic oligomers due to the nearly perpendicular conformation.
The external surface of a mesoporous silica, MCM-41, was functionalized with phenyl groups to obtain dual domain mesoporous silica particles (hydrophobic particle surface and hydrophilic mesopore) for a platform for the photochromism of merocyanine/spiropyran. Merocyanine was adsorbed on MCM-41 with that functionalized with phenyl groups by photoinduced adsorption. The red hybrid of Ph-MCM-41 showed negative photochromism with a higher decolorization efficiency and a faster thermal colorization than the hybrid of MCM-41, suggesting the photogenerated spiropyran diffused into the hydrophobic surface.
We report, for the first time, metal (Pd) nanocrystals (NCs) covered with a 2D flexible metal–organic framework (MOF) of [Zn(NO2-ip)(bpy)]n (NO2-ip: 5-nitro-isophthalate, bpy: 4,4′-bipyridine). The hybrid materials were characterized by powder X-ray diffraction measurements and transmission electron microscope techniques. The CO2 sorption and hydrogen storage properties revealed that both the flexible porous character of the MOF and the hydrogen absorption ability of Pd NCs were compatible in the hybrid.
Cocrystals of syndiotactic polystyrene (sPS) with polyethylene glycol (PEG) has been manufactured by using a guest exchange procedure to date. However, the guest exchange procedure is expected to be impractical for cocrystallization with high-molecular-weight PEG. This is because the higher the molecular weight of the guest PEG, the longer the time required for this procedure. To solve this problem, a new manufacturing process for sPS/PEG cocrystal film formation by casting a binary solute solution, has been developed. This simple procedure is applicable to even PEG with molecular weight of 20000.