THz wave emission from ZnTe nano-colloidal aqueous dispersion flow (the particle size is 5-nm in diameter, the flow thickness is 17 µm) with two different particle densities (1.60 mmol/L and 1.07 mmol/L) was measured by time-domain spectroscopy (TDS) under femtosecond laser irradiation (>35 fs/transform-limited, 800 nm, horizontally-polarized, 0.5 kHz) in air. Intensity increase and peak shift in the TDS signal wave-form if compared with distilled water indicate that THz wave emission is induced in ZnTe nano-particles in the aqueous dispersion.
After thermally curing p-tert-butylcalix[8]arene glycidyl ether with benzoxazine, the thermal, mechanical, and dielectric properties of the copolymer products were evaluated. Incorporation of p-tert-butylcalix[8]arene glycidyl ether into the benzoxazine resin greatly increased both the glass transition and the thermal decomposition temperatures. Conversely, the fracture toughness of the polymer network decreased as the epoxide content increased, and the highest flexural strength was found in the sample with an epoxide/oxazine molar ratio of 10/90.
Conjugates of thermo-responsive poly(N-isopropylacrylamide) with cyclophane monomers and pentamers were synthesized. The conjugates exhibited lowest critical solution temperatures (LCSTs) and each aqueous solution of the conjugates became turbid above their LCSTs upon heating. The conjugates have enough water-solubility below their LCSTs and bound fluorescence guests. Heating of the conjugate-guest solutions followed by centrifugation gave insoluble materials (captured guests and the conjugates). The efficiency of guest-separation from bulk aqueous phase by the pentamers was much higher than those by the monomers.
The ability to control structure and function of metal-organic cages by external stimuli offers many possibilities. For example, preventing product inhibition in catalysis, releasing a drug at a specific site, or altering material properties. This Highlight Review describes the different strategies that have been developed to make light-responsive metal-organic cages able to undergo a structural change in response to a light stimulus and furthermore, major challenges and future perspectives are discussed.
Herein reported is a dehydrative allylation reaction of 2-alkylbenzophenones with allylic alcohols promoted by light and palladium. Photoirradiation of 2-alkylbenzophenones generates nucleophilic species which couple with allylic alcohols. Mechanistically, in-situ generated carboxylic acid is likely to activate allylic alcohols to facilitate the palladium-catalyzed allylation reaction.
One of the challenging targets in materials synthesis is a direct conversion of molecular based crystalline substances into crystalline ordered carbonaceous frameworks (OCFs). Though we have discovered the first example of the direct conversion with Ni-cyclic porphyrin dimer bridged by diacetylene moieties, such dimer requires a multi-step synthesis procedure with low yield and the resulting OCFs are not highly porous. Herein, we report the direct conversion of Ni-porphyrin monomer with ethynyl groups into OCF with developed microporosity. Upon heat-treatment, Ni-porphyrin monomer is thermally polymerized via ethynyl groups and the resulting polymer is successively converted into OCF at 873 K. Thus, ordered microporous material with conductive carbonaceous framework is obtained. The porphyrin Ni-N4 coordination structure is well retained after the carbonization and the microporous OCF exhibits specific electrocatalysis for CO2 conversion into CO with high selectivity.
Recent developments in controlling polymer assemblies using metal–organic frameworks (MOFs) are covered in this highlight review. The characteristic features of MOFs are their highly tailorable and well-defined nanoporous structures that can be utilized for specific polymer nanoconfinement. This methodology allows us to regulate assembly structures of polymers for the fundamental study of polymer properties, as well as construction of functional MOF–polymer nanohybrids.
A practical, metal-free carbonyl C(sp2)–H oxidative alkynylation of aldehydes with hypervalent alkynyliodine reagents without the use of any catalysts is described for the synthesis of various α,β-alkynyl ketones. Here, two different methods have been developed where limiting reagents or substrates can be switched, and adopted according to the valuableness of aldehyde substrates or hypervalent alkynyliodine reagents. These reactions proceed with a broad substrate scope and high functional-group compatibility.
A copper-catalyzed regioselective hydrodefluorination of 1-trifluoromethylalkenes with hydrosilanes has been developed. The copper catalysis is compatible with several functional groups, including alkyl chloride, ether, ester, nitrile, and imide moieties, to form the corresponding gem-difluoroalkenes in good yields. Additionally, asymmetric induction is also possible by using the chiral DTBM-SEGPHOS ligand, and gem-difluoroalkene with point chirality at the allylic position is obtained with high enantioselectivity.
We employed two modes of atomic force microscopy to characterize the nanophase-separated structure of a block copolymer thin film from poly(2-methacryloyloxyethyl phosphorylcholine) and poly(3-(methacryloyloxy) propyl-tris(trimethylsilyloxy) silane) in aqueous solution. The force-spectroscopic mapping mode clearly revealed a mismatch between nanophase arrangement and topography. This mode resolved the nanophase arrangement better than the amplitude-modulated scanning mode, whose phase-delay images were more common in visualizing the chemical distribution. Nevertheless, characterization with both modes allowed us to deduce the three-dimensional structure of the copolymeric films.
We demonstrated a ruthenium-catalyzed regioselective allylic amination of tertiary allylic esters with various amines using [Cp*Ru(CH3CN)3][PF6]/5,5′-dimethyl-2,2′-bipyridine (5,5′-diMe-2,2′-bpy) and related ruthenium catalytic systems, and successfully obtained a diverse range of α-tertiary amines as single regioisomers. The present ruthenium catalytic system was effective for reactions with various types of amines.
Herein we report the mass-production of Cl-doped graphene nanodots through the implementation of pulsed plasma on graphite rod in CHCl3 medium. The Cl-doped graphene shows the band gap, which is assigned as p-type semiconductor by kelvin probe force microscopy (KPFM) measurement. The current findings revealed not only the semiconducting nano graphene with significant Cl insertion through pulsed plasma method but also opened a facile route for mass production of elemental doped 2-D layer materials using a wide range of organic solvent.
To achieve high energy-efficiency and to tailor product distribution, pyrolysis followed by CO2 gasification (with the CO2 conversion up to 85%–98%) was proposed for preparation of pine sawdust derived carbons. Effects of the gasification conditions were investigated on properties of the as-prepared carbons. Hierarchically porous carbons can be obtained with some heteroatoms (O and Cl) and thus showing a good capacitive performance (with the capacitance up to 225 F/g at 1 A/g).
Gold nanoparticles (AuNPs) were in situ electrodeposited on n-type GaN (n-GaN) electrode via cyclic voltammetry for electrochemical sensing of hydrogen peroxide (H2O2). Detection results revealed the H2O2 detection range was from 40 µM to 1 mM, and the detection limit was 10 µM, moreover, AuNPs/n-GaN electrode showed quick response (less than 1 s) and high sensitivity (164.0 µA mM−1) toward H2O2 detection. Furthermore, AuNPs/n-GaN electrode exhibited good selectivity, and excellent mechanical and storage stability. In addition, AuNPs/n-GaN electrode showed accurate responses toward diluted human serum samples with 50 µM H2O2, which indicated AuNPs/n-GaN electrode has potential for biomedical study.
Metal–organic polyhedra (MOPs) are discrete porous materials which feature intriguing structures, well-defined cavities, and emergent functions. Among them, the recently developed Rh(II)-based MOPs represent a class of novel assemblies with robust structures, facile processabilities, and versatile functions thanks to the strong Rh–Rh bonds in the paddle-wheel units and the rich chemistries of the unsaturated Rh sites. These distinct characteristics make Rh(II)-based MOPs a prominent platform for the construction of functional materials with integrated discrete porosities. Therefore, in this mini-review, we highlight recent development and advances of Rh(II)-based MOPs as well as their applications from modular entities to supramolecular soft matter.
C(sp2)–H iodination of m-xylene promoted by a rhodium(III) complex supported by a redox-active ligand, (nBu4N)[RhIIIL3−(MeCN)Cl] (1Cl), is reported. The iodination reaction involves an electrophilic C(sp2)–H metalation of m-xylene and successive iodine atom insertion into the rhodium(III)-carbon bond. The organometallic complex intermediate has been characterized as (nBu4N)[RhIIIL3−(κ-C-C6H4-3,5-Me2)(H2O)] (2Ar) by various spectroscopic techniques as well as crystal structure analysis. The production of 3,5-dimethyliodobenzene from 2Ar accompanies conversion of 2Ar to the diiodido complex, (nBu4N)[RhIIIL•2−(I)2] (3), in which one-electron oxidized dianionic radical ligand L•2− is involved. Based on these results, mechanism for the C(sp2)–H iodination is discussed.
The combination of 4-phenyl substituted pyrazolate ligand, LEt(Ph)H (4-phenyl-3,5-diethyl-1-pyrazole) with coinage metal(I) salts gave cyclic structures, [CuLEt(Ph)]3, {[AgLEt(Ph)]3}2, and [AuLEt(Ph)]3. Both [CuLEt(Ph)]3 and [AuLEt(Ph)]3 were trinuclear, while {[AgLEt(Ph)]3}2 was hexanuclear with two intermolecular argentophilic interactions. {[AgLEt(Ph)]3}2 formed arene-sandwiched, π acid/base complexes, {[AgLEt(Ph)]3}2(mesitylene) and {[AgLEt(Ph)]3}2(toluene). Photoluminescent spectra of the Cu(I) and Ag(I) complexes were dominated by closed shell d10-d10 M•••M interactions, whereas those of the Au(I) complex exhibited ligand-based emissions.
Molecular pyrene, 1-hydroxylpyrene, and 2-hydroxypyrene in chloroform and embedded in poly(methyl methacrylate) film reveal mirror-image magnetic circularly polarized luminescence (MCPL) when south (S)-up or north (N)-up direction of the longitudinal external magnetic field of 1.6 T to unpolarized incident light (Faraday geometry) is employed. The |gMCPL| magnitude is on the order of 10−3 T−1 in 374–416 nm. The sign of MCPL is controlled by the S-up and N-up geometry and by the position (1- or 2-) of the hydroxy group.
Hollow N-doped carbon/metal phosphate (HNC/MP) structure is prepared via the reaction of ZIF-8@ZIF-67 with NH4H2PO4, and ultra-small nanoparticles (metal phosphate, etc) are evenly embedded in amorphous carbon walls. Evaluating for a Li-S battery, HNC/MP composites with 62 wt % sulfur exhibits a large initial capacity of 921 mA h g−1 at 800 mA g−1, an impressive cyclability of 580 mA h g−1 after 200 cycles and good rate performance of 637.1 mA h g−1 at 1600 mA g−1, which are chalked up to phosphorization and hollow structure.
A novel inhibition assay by capillary electrophoresis/dynamic frontal analysis (CE/DFA) is proposed. When substrate p-nitrophenyl phosphate and inhibitor theophylline were tandemly introduced into a capillary containing alkaline phosphatase enzyme, two plateau signals were detected in the electropherogram. A higher plateau is based on the CE/DFA without inhibition, and a suppressed plateau is formed while the substrate zone passes through the inhibitor zone. Inhibition constant was successfully determined through the two plateau heights.
A triarylamine bearing three benzofuran rings was designed and successfully prepared in 64% yield. It exhibited absorption at 385 nm, and blue emission at around 440 nm with a fluorescence quantum yield of 0.57. This compound showed high heat resistance and reversible one-electron oxidation. Upon one-electron chemical oxidation, a near-infrared absorption was revealed due to a persistent radical cation species. DFT calculations also supported the experimental data.
A site-selective direct C–H arylation protocol for the triptycene skeleton is developed using copper catalyst and diaryliodonium reagents. With the aid of directing groups, C3-symmetric trisubstituted triptycenes are selectively synthesized, and the structure was determined by X-ray diffraction analysis. Further derivatization of the installed bromo functionalities is also described.
Due to the increasing resistance of pathogens to antibiotics, novel antibacterial nanocomposite materials have been attracting increasing research interest. Herein, we report a facile synthetic method for a novel highly antibacterial nanocomposite based on graphene oxide (GO) nanosheets decorated with cuprous oxide by a two-step method. The as-prepared nanocomposites were comprehensively characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX) spectroscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nanocomposite was investigated for antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using the medium dilution method and the disc diffusion method. The results showed that the synthesized Cu2O-GO has good antibacterial activities. At the nanocomposites concentration of 100 µg/mL, the inhibition rate against E. coli reached 68%, while the inhibition rate against. S. aureus reached 32%.
Metal/metalloid complexes have been commonly used in medicine as either therapeutic or diagnostic agents. Understanding the molecular mechanisms of action of metallodrugs is crucial for the development of more effective metallodrugs. Metalloproteomics serve as important tools for systematic analysis of metal-bound proteins within a cell or tissue type. Inductively coupled plasma mass spectrometry (ICP-MS), has been widely employed by metalloproteomic approaches. We summarize the latest progress of ICP-MS-based metalloproteomic approaches for the identification of putative protein targets of anticancer and antibacterial metallodrugs with the purpose of exploring their molecular mechanisms of action. The approach can also play a role in systems biology and precision medicine.
This study reports a facile strategy to prepare IrOx nanoparticle films on FTO substrates through simple spin-coating, annealing, and plasma treatment, which act as efficient electrocatalysts towards oxygen evolution reaction (OER). Typical amorphous IrOx nanoparticle film obtained by annealing at 300 °C and air-plasma treatment exhibits excellent OER performance in acidic electrolyte with a low overpotential of 290 mV at 10 mA cm−2, a Tafel slope of 55.4 mV dec−1, and an ultrahigh mass activity of 993 A g−1 at 1.55 V, which is among the best compared to the results reported in the literature.
An efficient synthesis of morpholine derivatives has been developed using indium(III)-catalyzed intramolecular reductive etherification reaction. This method allows the construction of various 2-substituted, and 2,3-, 2,5-, 2,6-disubstituted morpholines with good to excellent yields and high diastereoselectivity. In addition, this method demonstrates good compatibility with a broad range of functional groups.
In this paper, magnetic substrate, molecular imprinting technology (MIT) and surface-enhanced Raman scattering (SERS) technology were combined to prepare core-shell magnetic molecularly imprinted polymer Fe3O4@SiO2@Ag-MIPs for quantitative detection of ofloxacin. The results showed that the concentration of ofloxacin within the range of 10−3–10−8 mol/L showed a good linear relationship with the Raman peak intensity at 1416 cm−1. The prepared molecularly imprinted polymer had excellent uniformity and dispersibility. Raman testing of commercially available ofloxacin eye drops showed good recovery, indicated that it can be used for the quantitative detection of actual samples.
Inorganic nanosheets obtained by exfoliation of layered crystals of hexaniobate in water form colloidal liquid crystals. We found that they develop various structural colors by moderating nanosheet concentration and ionic atmosphere.
Reaction of dianionic diborane(4) with [Rh(cod)Cl] afforded a dinuclear Rh(I)−/Rh(I)+ complex through C–H bond cleavage. The resulting complex was characterized by NMR spectroscopy and X-ray analysis. The UV-Vis spectrum of the resulting complex exhibited an absorption at 580 nm, which can be assigned as MMCT transition between electron-rich and -poor Rh centers.
Five new ternary iron(III) complexes with phenolate-based ligands of general molecular formula, [Fe(L1)B] and [Fe(L2)B], where L1 = 2-(bis(2-hydroxybenzyl)amino)acetic acid, L2 = 2-bis[3,5-di(tert-butyl)-2-hydroxybenzyl]aminoacetic acid, B = phen (1,10-phenanthroline), ip (1H-imidazo[4,5-f][1,10]phenanthroline) and pyip (2-(pyren-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) were synthesized and probed for visible light-induced cytotoxicity in human cervical carcinoma (HeLa) cells. The complexes in generating hydroxyl radicals from molecular oxygen on visible light-induced phenolate(O)→Fe(III) or carboxylate(O)→Fe(III) charge transfer prompted apoptosis in HeLa cells with IC50 values in the range of 4.6–24.3 µM while remaining non-toxic in dark.
We investigated clay-catalyzed thermal isomerization of methylated naphthalenes. Methylated naphthalenes were heated with montmorillonite, kaolinite, sericite, and CaCO3. Immature coal was heated with and without montmorillonite. Our experiments showed that montmorillonite and kaolinite promoted isomerization of methylated naphthalenes. The high protonation ability and large specific surface area of montmorillonite may have controlled the isomerization rate. The results suggest that coexisting clay minerals will affect the maturation of sedimentary organic matter in the natural environment.
Annulation of α,β-unsaturated amides with electron-deficient 1,3-dienes gave 5,6-dihydropyridin-2(1H)-ones in the presence of a hydroxoiridium catalyst. The reaction proceeded via direct C–H alkylation of acrylamides with conjugated dienes, followed by intramolecular aza-Michael addition, thus giving dihydropyridinones stereoselectively in good yields.
A liquid arylazopyrazole derivative is newly synthesized as molecular solar thermal fuel. It shows efficient trans-to-cis photoisomerization in the neat liquid state, with the cis-isomer having a significantly longer thermal half-life (t1/2 = 3,069 h, at 25 °C). It overcomes the limited thermal stability of the corresponding liquid cis-azobenzene derivative (t1/2 = 16 h) and marked a gravimetric energy density of 41 kJ·mol−1, which meets the requirement for thermophysical heat storage applications.
Monoclinic WO3 is considered to be a promising photoanode due to high theoretical photocurrent density and quantum efficiency. However, the practical photoelectrochemical (PEC) performance is considerably inferior to the theoretical value because of severe surface charge recombination. Herein, an Ag nanoparticle (NP) modified WO3 composite photoanode was prepared via in situ cathodic reduction to boost the surface charge separation. The various PEC performance indicators such as the photocurrent, incident photon-to-current efficiency, and applied bias photon-to-current efficiency have been improved to varying degrees upon the modifications of the Ag NPs. Electrochemical impedance spectroscopy and Mott-Schottky analysis demonstrate that the Ag NPs greatly enhance the surface charge separation efficiency of WO3, thus improving the PEC performance.
We have theoretically analyzed the geometrical H/D isotope effect of HNO•••XH2NH2 (X = B or Al) and HNO•••BH3NH3 systems with the aid of multicomponent quantum mechanics (MC_QM) method, which can directly include the nuclear quantum effect of hydrogen nuclei. We demonstrate that deuterium substitution of positively charged hydrogen in blue-shifting dihydrogen-bonded clusters leads to elongation of the dihydrogen-bonded distance, whereas the substitution of negatively charged hydrogen leads to contraction, as is the case in red-shifting dihydrogen-bonded clusters.