Superhydrophobic surfaces were unexpectedly constructed by immersing a variety of substrates (aluminum sheet, melamine sponge, cotton fabric, and wood) into an aqueous solution containing tea polyphenols and metal ions (Fe2+, Ag+, Ce3+) and the potential applications in corrosion resistance for superhydrophobic aluminum, water absorption resistance for superhydrophobic wood, oil/water separation for superhydrophobic sponge and self-cleaning for superhydrophobic fabric were investigated.
The proton permeation ability of graphene has been highlighted for use as proton exchange membranes in electrochemical devices. However, the tunability of proton permeation is still limited. We have developed molecular models for the theoretical study of the proton permeation ability of modified single-layer graphene structures. Energy calculations were employed for the evaluation of the barrier height and permeation rate. The proton permeation is tunable by the presence of covalently bonded molecules, which is useful for the design of tunable interfaces for proton permeation.
A novel Mannich reaction of α-aminomaleimides with N-arylsulfonylimines was conducted in dimethyl sulfoxide using molecular sieves 4A. Remarkably promising new maleimide derivatives were efficiently and readily synthesized under mild reaction conditions.
An amphiphilic cyclophane dimer (1), which was constructed with two cyclophane skeletons, each having three hydrophobic side-chains with Boc-protecting amino groups, and a hydrophilic polyethylene glycol (PEG) linkage, was synthesized. Amphiphilic compound 1 was found to form self-aggregate in aqueous media. In addition, 1 exhibited lowest critical solution temperature (LCST) behavior and its aqueous solution became turbid above the LCST upon heating. Moreover, pH-induced disaggregation of the self-aggregates of 1 was successfully performed upon addition of hydrochloric acid, to produce a cationic water-soluble cyclophane dimer (2) by the removal of the Boc-protecting groups of 1.
The use of safe and environmentally friendly materials is an important issue for industrial mass production processes. In this study, we demonstrate the deposition of tin halide perovskite films using environmentally benign 2-propanol as a solvent. Sequential deposition of 2-propanol solutions containing SnBr2 and CH3NH3I led to the formation of CH3NH3SnBr3−xIx, which exhibited good crystallinity and visible-light absorption.
Polysiloxanes have high oxygen permeability coefficient (PO2) and low oxygen separation factor (α = PO2/PN2) and polyimides high α and low PO2. To obtain polymers with high α and PO2, novel alternating copolymers containing disiloxane and imido groups were synthesized by hydrosilylation polyaddition. In spite of low molecular weights, no groups making hydrogen bonds, and relatively high content of siloxane moieties of the resulting polymers, they showed good membrane forming ability and good performances above the Robeson upper bound.
In this study, phenolphthaleins have been introduced into hybrid tetraarylethylene bridged six-membered benzene rings and five-membered thiophene rings to construct new multifunctional molecules responding to UV/Vis light, acid/base and water. Results showed that the titled molecules exhibited distinctive photochromism and acid-base discoloration in solution, PMMA and solid state, and displayed typical aggregation-induced emission in a mixture solution of water and THF. Their fluorescence emission switched by acid, base and light stimulations were further investigated. These versatile properties are expected to provide a new choice for the application in fluorescence detection or molecular switches.
An efficient synthetic method for thioxanthones from 3-halobenzoic acid esters is disclosed. Directed ortho-lithiation of 3-halobenzoic acid esters and following arylthiolation realized the synthesis of sterically congested 2-(arylthio)-3-halobenzoic acid esters. Diverse thioxanthones were prepared by subsequent TfOH-mediated cyclization.
The gas-phase •OH and •H radicals derived from the moisture of helium atmospheric-pressure plasma (He-APP) were detected at the gas–liquid interface by means of a flow spin-trapping electron spin resonance (FS-ESR) method using a newly developed micro open-flow (MOF) reactor that was exposed to He-APP.
The formation of amide bonds is important in many areas of chemistry, and the ligation by condensation of N-hydroxylamine and an α-keto acid has been attracting increasing attention. Porcine kidney d-amino acid oxidase, which catalyzes the oxidative deamination of amino acids to yield α-keto acids, ammonia, and hydrogen peroxide, and native chemical ligation were used to access α-keto acids, and amides were synthesized with N-hydroxylamine. d-Phenylalanine was converted to phenylpyruvic acid obtained by recombinant pig d-amino acid oxidase in high yield (97%). The α-keto acid was ligated with N-benzylhydroxylamine and N-hydroxylphenylalanine in N,N-dimethylformamide, and benzyl-2-phenylacetamide and (2-phenylacetyl)phenylalanine in 82% and 79% yields, respectively. Other amide compounds were also obtained via this synthesis.
The vapor-phase catalytic reaction of crotyl alcohol (CRO) was investigated over metal oxide-modified silica catalysts. The isomerization of CRO to 3-buten-2-ol (3B2OL) was found to progress in the reaction of CRO over V2O5-modified SiO2 (V2O5/SiO2) at 200 °C. V2O5/SiO2 showed high 3B2OL yield and stable catalytic activity. The isomerization between CRO and 3B2OL reached an equilibrium without the dehydration to 1,3-butadiene. Poisoning experiments using dimethylpyridines suggested that Lewis acid sites acted as the active centers.
We previously reported a light-sensing system composed of PSI (photosystem I) and graphene-FET (field effect transistor). The photoresponse could be observed only when surfactants and NaASC (sodium l-ascorbate) were added to the electrolyte. To clarify the properties of graphene-FET as a photosensor, the effect and mechanism of action of surfactants were investigated and discussed. Surfactants with longer alkyl chains can suppress undesired shifts in the Dirac point (charge neutrality point) induced by NaASC.
Siloxane-based nanoporous materials have a wide range of applications. In this study, a double-four-ring cage siloxane modified with dimethylsilanol groups at eight vertices was cross-linked via reaction with titanium(IV) tetraethoxide to construct a three-dimensional network with Si–O–Ti bonds, producing a nanoporous material. The product exhibited catalytic activity for the liquid-phase oxidation of cyclohexene with relatively high selectivity. This building block approach opens a new route to nanoporous materials composed of fully inorganic Si–O–Si and Si–O–Ti linkages.
Unusual complex formation of PtBr4 in THF was investigated for phenylazomethine dendrimer templates. The characteristics made it possible to reverse-order assemble platinum salts by changing the solvent composition of the dendrimers. This reverse-order assembly method enabled full-range tuning of metal ratios for hybridization, which was inherently difficult for templates with a typical dendritic structure.
In this work, a simple and energy-saving method for oleylamine (OLA) modified CsPbBr3 was reported and the influence of OLA on the stability and solubility of CsPbBr3 was explored in detail. With the increase of OLA, the solubility of CsPbBr3 increases first and then decreases. However, the stability of CsPbBr3 is proportional to the amount of OLA.
Two new CuII coordination polymers with bis-imidazole ligand, bitrb, were synthesized and characterized. Reaction of CuSO4·5H2O with bitrb in a MeOH-H2O mixed solution produced a 2D coordination polymer, while a similar reaction in a THF-MeOH mixed solution gave a 1D coordination polymer. The former compound converts to the latter in a THF-MeOH mixed solvent, while the reversed reaction proceeds in MeOH-H2O media. Their crystal structures and the reversible transformations depending on the present solvents are described.
In this study, peroxydisulfate (S2O82−) was used as a co-reactant for the first time to generate a highly stable cathodic electrochemiluminescence (ECL) of rhodamine B (RhB) on a glassy carbon electrode. The ECL emission spectrum is almost identical to its photoluminescence spectrum and the intensity is significantly enhanced in the presence of nonionic surfactant TritonX-100.
Molecular dynamics simulations were performed to investigate the interfacial liquid structure at the solid interface of a ethanol-cyclohexane mixture, a typical system with micro-heterogeneity in the liquid bulk. The degree of micro-heterogeneity was decreased, not only when the solid surface was hydrophilic as previously reported, but also when it was hydrophobic. However, the microscopic mechanism was different. The hydrophobic surfaces restricted the molecular orientation of ethanol, and hence, sterically suppressed the clustering of ethanol molecules in the in-plane direction.
Thanks to the binding of various metal ions, metalloprotein plays an essential role in many different biological processes and represents an indispensable protein subgroup. Thus, the knowledge of the incorporated metal site and metal-ligand coordination bond in the protein is invaluable for understanding this critical bio-macromolecule and designing a new one. Over the last decade, atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS) has been used to explore the metalloprotein as an emerging methodology, focusing on measuring metal-ligand bond strength. By stretching the protein molecule along its peptide backbone, AFM-SMFS can unfold the protein secondary structure and break and quantify the metal-ligand bond/metal cluster. Moreover, the very recent development of enzymatic, site-specific protein conjugation and immobilization methods for the SMFS system enables the highly efficient and accurate measurement of the metal-ligand bond strength in proteins. As a result, comparing the strength among different types of metal-ligand bonds in proteins becomes possible, and the trend of their strength is gradually revealed, such as the Fe(III)-ligand bond in iron-binding proteins. Thus, we envision that in the future AFM-SMFS may provide a unique insight to uncover the general principle of how protein selectively binds to metal ion.
Core-shell structured hierarchical SSZ-13 microspheres with mesopore and zeolitic micropore were obtained via combining zeolite crystallization and post-synthesis fluoride etching. Secondary pores in core-shell SSZ-13 crystals were then formed by fluoride-containing chemical etching post-treatment routes. The samples were systematically characterized by XRD, SEM, N2 adsorption/desorption, and NH3-TPD measurements, indicating that the fluoride-treated SSZ-13 samples exhibit core-shell structure, high crystallinity, large specific surface area, and acidity. It is worth mentioning that the core-shell structured hierarchical SSZ-13 catalyst exhibited superior MTO catalytic performance with higher selectivity to ethylene and propylene as well as prolonged catalytic lifetime in comparison to the untreated SSZ-13.
Thermolytic reactions of 9,10-diphenylanthracene endoperoxide (1) and its derivatives having deuterated phenyl groups and phenyl groups with fluorinated substituents were investigated as chemiluminescence (CL) reactions proceeding by heating crystal samples. While heated crystals of 1 showed negligible CL, CL emissions from singlet oxygen (1O2) generated by thermolyses of the derivatives were observable in the heated solid-liquid mixture states, indicating that the modifications for the derivatives were effective to suppress the 1O2 deactivation.
Alkylbenzenes coupled with isocyanates at the benzylic position upon irradiation with visible light in the presence of an iridium photoredox catalyst, a bromide anion, and a nickel catalyst, producing N-substituted α-aryl amides. An analogous carbamoylation reaction of aliphatic C–H bonds of alkanes took place when UV light and a diaryl ketone were used instead of visible light and the iridium complex. The present reaction offers a straightforward and atom-economical method for the synthesis of carboxamides starting from hydrocarbons with one-carbon extension.
The first absolute optical resolution only by circularly polarized light without any chiral compounds has been developed by serially connecting the two enantioselective reactions we developed, that is, the enantiomer-selective helix-sense-selective polymerization and helix-sense-selective decomposition by circularly polarized light. The optical yield was high, 78% ee for menthol.
Herein reported is a photocatalytic cycloaddition reaction of triarylphosphines with alkynes. Phosphonium salts of unique bicyclic structures are synthesized through a radical pathway under mild reaction conditions. The phosphonium salts are subjected to the Wittig olefination reaction to afford structurally interesting phosphine oxides.
We successfully prepared boroxazolidones by the reaction of diarylborinic acids substituted with electron-withdrawing groups and α-amino acids with various substituents under physiological conditions. β-Amino acids and the bioactive compound biocytin also formed related chelate compounds in good yields. Since the reaction proceeded smoothly under moderate conditions in the presence of other functional groups, it could be a powerful tool for the target identification of bioactive molecules.
Trimethylamine N-oxide (TMAO) protects proteins against denaturing stresses. In this study, a vinyl polymer with a TMAO side chain was synthesized and its effects on protein stabilization were evaluated. UV spectroscopy analysis showed that the polymer exhibited protein stabilization characteristics. Furthermore, an enzyme activity assay indicated that the polymer showed a remarkable preservation effect at 4 °C compared to other commonly used additives. Therefore, TMAO-bearing polymer can potentially be used as a stabilizer for biochemical and pharmaceutical applications.
We report a novel type of Pd-BFBAPy-COF (Pd-COF) loaded with Pd-NPs was synthesized for the first time by using “two-in-one” imine covalent organic framework materials as carrier. By using BFBAPy-COF (Py-COF) as the carrier and H2PdCl4 as the palladium source, Py-COF and Pd-NPs were combined by a simple heating and reflux method to successfully prepare Pd-COF. Through X-ray photoelectron spectroscopy (XPS) and other methods, it is proved that the loading of Pd-NPs on Pd-COF is completed by coordination. Finally, the application of Pd-COF as electrode coating material in the detection of Bisphenol A (BPA) by differential pulse voltammetry (DPV) shows that Pd-COF has a good electrochemical induction to BPA. This work provides a cheap and facile synthesis route for the preparation of an electrochemical detection material with practical value.
A novel sandwich N-fused porphyrin rhodium complex (Rh-1-Br) comprising a brominated N-fused porphyrin (1-Br) and an isomerized cyclooctadiene ligand was synthesized and characterized. X-ray crystallographic analysis revealed a 1,5-cyclooctadiene isomerization into allylic C–H activated κ1,η3-C8H12 unit bound to the Rh center. The rotational dynamics of κ1,η3-C8H12 ring in Rh-1-Br was discussed using 1H NMR spectroscopic analysis and DFT calculation.
Real-time observation of an electrochemical reaction at a solid–liquid interface was performed using fluorescence-yield wavelength-dispersive soft X-ray absorption spectroscopy (XAS). A dedicated electrochemical cell was prepared for this study. As a model experiment, an electrochemical oxygen evolution reaction (OER) was observed in alkaline solution (0.1 M NaOH) on the surface of a Pt thin film working electrode. With positive potential shift, the XAS signal at K-edge of oxygen, whose peak position is close to that of gas-phase O2, increased in correlation with the electrode potential. This method has potential as a real-time observation method for time-dependent processes in various fields using electrochemical reactions at the solid–liquid interface, especially electrochemical catalytic reactions.
In the present paper, we report the mechanism of water and oil repellency (both static and dynamic) of methacrylate-based polymers with fluoroalkyl group side chains. Surface rearrangement has the greatest effect on dynamic water repellency, although surface composition mainly affects static water repellency. However, both static and dynamic oil repellences are influenced significantly by the surface composition and the molecular aggregation states.
The dimethyl naphthalene composition is used as an indicator to estimate the source organic matter of crude oil. This study examined the effect of maturation on this indicator. Heating experiments were performed on dimethyl naphthalenes and immature coal. The composition of indicator naphthalenes in terrestrial organic matter decreased with maturation. This study concluded that the dimethyl naphthalene ratio can be used as an indicator of source organic matter at random mean vitrinite reflectance values of up to 1.3%–1.4%.
Hierarchical structure was successfully created in YNU-5 zeolite by a direct base-treatment. Although the unmodified YNU-5 catalyst was significantly deactivated by heavy coking in hexane cracking, the dealuminated catalyst was much less deactivated. Furthermore, the mesopore/micropore hierarchical structure in the YNU-5 zeolite catalyst suppressed deactivation more than the non-hierarchical, dealuminated YNU-5 with a similar Si/Al ratio. An increase in hexane conversion was also observed for the YNU-5 with hierarchical structure.