A concise access to C3-symmetric macrocyclic triimines was developed. When biphenyls having a formyl group on one phenyl group and an NHBoc group on the other phenyl group were treated with an excess amount of concentrated HCl in 1,4-dioxane, the detachment of the Boc group followed by a trimerization reaction via imine formation proceeded smoothly to afford C3-symmetric imine-linked macrocycles in good chemical yields.
Ni(benzimidazole)(2-methylimidazole) with two-dimensional structure is used as a self-template to synthesize carbon-coated Ni0.85Se (Ni0.85Se@C) composites. Ni0.85Se@C composites display a thin nanosheet structure (∼20 nm) with macropores (∼200 nm), which can effectively reduce the volume change. The carbon network can improve the electrical conductivity of the electrode material. When evaluated as anode material for sodium ion batteries (SIBs), Ni0.85Se@C composites deliver an excellent reversible capacity of 405 mA h g−1 at 200 mA g−1 after 100 cycles and a good rate performance with a capacity of 200 mA h g−1 at 3.0 A g−1.
An iron porphyrin complex bearing a hydroquinone moiety at the meso position was newly designed and synthesized. Electrochemical analysis revealed that it catalyzes CO2 reduction at a lower overpotential compared with an iron complex without a hydroquinone moiety. Experimental and theoretical investigation suggested that a hydroquinone moiety at the meso position stabilizes the coordination bond between the metal center and CO2 via a hydrogen bond interaction with the latter in the secondary coordination sphere.
High-performance electrochromic (EC) materials based on earth-abundant materials for EC window applications are crucial for energy conservation. We report a simple and feasible approach for fabricating an iron oxyhydroxide (FeOOH) hierarchical hollow sphere array via templating-assisted electrodeposition. We further examine the corresponding EC characteristics of this hierarchical hollow sphere array. A significant improvement in the switching kinetics and coloration efficiency of the hierarchical hollow sphere arrays is demonstrated, facilitating their promising applications as nanostructured EC materials in EC windows and other diverse electronic and optical nanodevices.
Cyclohexane is selectively oxidized to cyclohexyl hydroperoxide (P) by the reaction with hydrogen peroxide (H2O2) in the presence of a catalytic amount of osmium tetroxide (OsO4). The product is converted to cyclohexanol (A) by the treatment with PPh3. The catalytic reactivity of OsO4 is enhanced by adding a coordinative anion such as benzoate anion. Encouraged by this result, we have developed an OsO4-immobilized heterogeneous catalyst using mesoporous silica (SBA-15) containing carboxylate groups on the surface.
Amphiphilic block polydepsipeptides of AB-type and AB3-type (hydrophilic A block: poly(sarcosine), hydrophobic B block: poly(l-lactic acid)) were prepared, and the N-terminals were arranged by guanidium or guanidino-peptide nucleic acid for loading siRNA in a reverse polymeric micelle. The amphiphilic polymers were successfully dispersed and assembled into reverse micelles in triglyceride or diisopropyl adipate. With loading siRNA into the core of the polymeric micelles, the micelle size was reduced down to a diameter of 25 nm in the case of the guanidino-peptide nucleic acid used as the capturing site. This small-size reverse micelle may be available for a transdermal drug delivery system (DDS) for siRNA.
Liquid organic hydrogen carrier (LOHC) systems have recently gained great importance as a means for hydrogen storage and transportation. Since fast hydrogen storage into H2-lean organic molecules under mild conditions is an urgent issue in LOHC systems, the present review highlights recent advances in hydrogenation catalysts for aromatic and heteroaromatic LOHC compounds. The activity results of supported noble metal (mainly, Ru and Pt) and transition metal (typically, Ni) catalysts are discussed along with key catalyst properties including metal dispersion, H2 and substrate adsorption capacities, and hydrogen spillover by strong metal-support interaction. This contribution will serve as a guide to design and synthesize an efficient and durable hydrogenation catalyst towards practical LOHC systems in the near future.
The electron transport capabilities of helically twisted molecules were theoretically evaluated based on the decay constant of the exchange interaction (βJ) between terminal nitronyl nitroxide radicals using broken-symmetry unrestricted density functional theory (UDFT) calculations. A small βJ value (βJ = 0.16 Å−1) was estimated for a homogeneously π-extended helicene consisting of a helically fused oligo-phenanthrenes, which is less than half that of the original carbohelicene (βJ = 0.39 Å−1) and comparable to that of rylene (βJ = 0.13 Å−1). The excellent electron transport capability suggested by the small βJ of the π-extended helicene can be attributed to the olefinic electronic nature found inside the helical framework.
Donor-π-acceptor type porphyrin-fullerene dyads with an acetylene bridge were designed and synthesized. The dyad was found to produce a charge-separated state with a lifetime of 0.42 µs and a quantum yield of 0.78 in benzonitrile. The p-type dye-sensitized solar cells with the dyad exhibited higher photovoltaic performance than that with the porphyrin reference without the fullerene moiety.
Exfoliated and reduced graphene oxide (MEGO) was fabricated by rapid microwave irradiation. When MEGO was used as the electrode of 17 m NaClO4 “water-in-salt” (WIS) electrolyte-based supercapacitors, the cell exhibited stable double layer capacitant behavior up to 2.5 V, much higher than the electrochemical stable window of water. The MEGO exhibited high energy density of 22 Wh/kg at a power density of 12.5 kW/kg, attributable to fast motion of ion clusters in the large space of exfoliated nanosheets in MEGO.
Literature data based on the water gas shift (WGS) reaction have been analyzed using statistical methods based on machine learning (ML). Our ML approach, which considers elemental features as input representations rather than the catalyst compositions, was successfully applied, and new promising catalyst candidates for future research were proposed.
A continuous selective catalysis of 4-(Trifluoromethoxy)aniline, a key intermediate in the preparation of riluzole, was studied using a micropacked-bed reactor (µPBR) packed with Pt/BAC catalysts. The effects of technological parameters such as solvent types, gas flow rates and liquid flow rates were investigated. It was indicated that the continuous hydrogenation process exhibited higher efficiency, selectivity and safety with less energy consumption compared to the traditional batch reduction process. The newly developed reactor system demonstrated a sustained and stable catalytic performance after 20 h running.
Herein, we report an efficient method using transition metal catalysts for controlling atom-transfer radical cyclization elimination (ATRCE) and atom-transfer radical cyclization (ATRC) in the reaction of α-bromocarbonyls possessing a styrene moiety. An iron salt efficiently catalyzed the ATRCE to produce cyclic compounds possessing a C-C double bond. On the other hand, the copper catalyst produced halogenated cyclic compounds.
Temperature dependency of the 15N CP-MAS NMR spectrum were examined in quasi-one-dimensional bromo-bridged palladium compound [Pd(en)2Br](Suc-C5)2·H2O (Suc-C5 = dipentylsulfosuccinate), which shows mixed-valence (MV) to averaged-valence (AV) phase transition. Single and double peaks were observed at lower and higher temperature sides from the phase transition temperature, reflecting that they are AV and MV states, respectively. Peak-to-peak interval in the spectra steadily decreased upon cooling, showing the charge-density-wave (CDW) amplitude decreased accompanied by approaching the AV state.
Two kinds of cationic spherical polyelectrolyte brushes (SPB), quenched poly(methacryloxyethyltrimethyl ammonium chloride) brush and annealed poly(2-aminoethyl methacrylate hydrochloride) brush with polystyrene cores (PS-PMETAC and PS-PAEMH), were synthesized by photo-emulsion polymerization. The small and uniform gold nanoparticles (AuNPs) were successfully immobilized in these two SPBs. The chain layer extension of the quenched SPB loaded with AuNPs (SPB-Au) was more complete than that of the annealed SPB-Au in alkaline system. Compared the catalysis of the prepared AuNPs onto the two SPBs, it was found that the catalytic activity of AuNPs in quenched SPB is higher than that in annealed SPB.
Dibenzo[h,t]rubicene was synthesized from 1,5-dichloroanthraquinone via an internally dimethoxylated intermediate. In contrast to the planar conformation of rubicene, dibenzo[h,t]rubicene adopted a double-helicene-like structure due to the intramolecular steric repulsion around the fused benzene-rings. Theoretical calculation suggests that the helical inversion occurs frequently with an inversion barrier of 4.8 kcal mol−1. The HOMO–LUMO gap of dibenzo[h,t]rubicene is smaller than that of rubicene, resulting in its red-shifted absorption tailing to 690 nm.
A hybridization behavior of Vis-OFF/UV-ON type photoresponsive DNA tethering p-tert-butyl azobenzene (pDNA) was investigated using fluorescence and absorbance measurement. We found that the partial dissociation of pDNA duplex into single strands occurred during UV irradiation, whereas incubation in dark after UV irradiation induced duplex formation. This feature is commonly considered to be important for an experimental design of photo-controllable system utilizing azobenzene.
Mesoporous LTA-zeolites with a Si/Al molar ratios of 1.1–1.8 were synthesized using a template-free flow microwave heating system. Because the obtained mesoporous zeolites showed relatively lower hydrophilicity at RH < 50% and high CO2/N2 separation performance, it could be expected to provide a direct air capture of carbon dioxide for onsite usage in consumer sections.
The aggregation state of two new covalently bonded dinuclear boron-based dye complexes was controlled to fabricate white-light-emitting materials. The materials exhibit blue and orange emission, with a photoluminescence quantum yield of 16% for one of the complexes in the solid state. This study highlights the importance of molecular engineering through the control of dye aggregation as a fundamental technology for creating novel functional materials with interesting optical properties.
In this study, a high sensitivity bimetallic SERS substrate Au@Ag is introduced with an EF of about 2.03 × 1011 to construct a competitive SERS aptasensor integrated aptamer and magnetic capture for detection of cardiac troponin I (cTnI). The aptasensor shows low quantitative concentration of detection (0.01 ng/mL), great linear relationship (R2 = 0.993) between SERS intensity and Log value of cTnI concentration (0.01 ng/mL–1.00 ng/mL). The proposed method is a rapid and sensitive detection of SERS aptasenor for cardiac troponin I, which has great application potential in clinic detection.
One of the new strategies to treat autoimmune diseases is to target Siglec, a membrane protein receptor with the ability to suppress immune responses. Herein, we synthesized glycopolymers carrying 3′-sialyllactose in various glycounit densities. RAW 264.7 macrophages transfected to express secreted alkaline phosphatase (SEAP) were used to evaluate the immunosuppression ability of the glycopolymers. The inhibition of the signal transmission was dependent on the glycounit densities of the glycopolymers, and was maximized at the moderate density (70%).
We have succeeded in the synthesis of a 2-germaazulene stable in solution, in which the carbon atom at the 2-position of azulene is replaced by a germanium atom, the fourth period element in Group 14. The properties of the obtained 2-germaazulene were verified both experimentally and theoretically, indicating its sufficient aromaticity. In comparison with the parent azulene, significant differences were found in its orbital levels, charge distribution, and the resulting properties.
Binary oxide clusters (BOCs) composed of Cu and Bi atoms were prepared using a macromolecular dendritic template. The oxidized Cu16Bi12Ox exhibited selective styrene bisperoxidation. The catalytic performance and durability were improved by incorporation of Bi into the CuOx clusters.
The synthesis of Pd(II) and Cu(II) 10-azacorroles with a meso-NH group has been achieved through the thermal extrusion of one nitrogen atom from the corresponding diazacorrphycene metal complexes. We also found that oxidation of the Cu(II) 10-azacorrole complex afforded another type of copper 10-azacorrole with an imine moiety. The structural, magnetic, and electrochemical properties of these compounds were investigated to disclose the nature of two types of copper 10-azacorroles.
A stable diareno[a,f]pentalene, dinaphtho[2,1-a:2,3-f]pentalene 6, was synthesized and characterized. The nonsymmetrical dinaphtho-fused structure of 6 highly localized the π-electrons on the pentalene core, creating a quinoidal closed-shell singlet state with a weakened antiaromatic nature. Due to the relatively high HOMO level and the presence of CH–π contacts, the mesityl derivative 6b exhibited a hole mobility of 4.37 × 10−4 cm2 V−1 s−1, as measured by a space-charge-limited current (SCLC) method.
A hybridization chain reaction (HCR) using a serinol nucleic acid (SNA) scaffold was newly designed and optimized. We found that hairpins with 8- or 9-mer loops, toeholds, and stems activated HCR and that the SNA interface accelerated initiation of HCR. Use of nitromethyl red as a quencher on the hairpin enabled detection of target RNA with high sensitivity. This system will be applicable to RNA detection in cell and biopsy, due to the high enzymatic durability of SNA.
A CuO-CuAl2O4 nanocomposite (CuAl NC) synthesized by high temperature calcination of Cu-Al layered double hydroxides (CuAl LDHs) acted as an effective heterogeneous catalyst for acceptorless dehydrogenation of various alcohols. The catalytically active Cu0 species was formed by in situ reduction with alcohol. The catalytic activity strongly depended on the Cu/Al ratio in preparation and calcination temperature. The synthesized catalyst was reusable without loss of its high activity and selectivity.
To obtain the properties of nanopores solids, N2 is usually used as probe molecule, however recently, IUPAC recommends using Ar instead. This study used experimental X-ray diffraction (XRD) analysis, Monte Carlo (MC), and hybrid reverse MC (HRMC) simulations to obtain information on the intermolecular structures of adsorbed N2 and Ar. Our results indicate that the quadrupole interaction between N2 molecules is relatively weak, and the N2 gives fairly good assessments as with Ar for porous carbons with low functional groups.
The hydrogen/deuterium isotope and oxygen/sulfur homologue effects on the absolute nuclear magnetic shielding constants were theoretically analyzed for five 17O-water isotopologues and five hydrogen sulfide isotopologues. Using both ab initio calculations and anharmonic vibrational structure calculations based on vibrational quantum Monte Carlo theory, we confirmed that the changes in the atomic charges are strongly correlated with the enhancements of the absolute nuclear magnetic shielding constants.