Copper(II) porphyrin-catalyzed coupling of alkyl tosylates and alkyl Grignard reagents afforded substituted alkanes. The role of the copper(II) porphyrin complex was examined using EPR and in-situ synchrotron-based X-ray absorption fine structure measurements. These studies suggested that neither Cu redox nor substitution via in-situ generated cuprate was involved in catalysis. The results supported a reaction mechanism involving single electron transfer from copper(II) porphyrin to tosylate to facilitate the nucleophilic addition of Grignard reagents.
An operationally simple one-pot protocol for the synthesis of a variety of trichloromethylated tertiary amines from anthranilic acid, imines, and chloroform was achieved. This reaction proceeds via in situ imine formation followed by the addition of benzyne prepared from anthranilic acid with concomitant proton abstraction from chloroform. By employing this method, a series of β-trichloromethylated anilines were synthesized in moderate to good yields in gram scale. Basic hydrolysis of trichloromethylated dihydoquinoline gave dichloromethylene-1-phenylquinoline in quantitative yield.
This is the first demonstration to utilize mesoporous zeolite as a composite bi-functional adsorbent, where the adsorption site is located in the micropore, and a phase-change material (PCM) is installed in the mesopore to absorb the heat of adsorption, to realize an ideal, isothermal-adiabatic adsorption process.
We assessed foam stability in ethanol/water mixtures in the presence of an anionic surfactant, sodium dodecyl sulfate, with long-chain alcohols. The foam stability was significantly improved by the coaddition of the long-chain alcohols. We found that adding the long-chain alcohols increased the surface viscosity, by forming a mixed adsorption film at the air/solution interface.
Methoxy-(7a), bromo-(7b), CF3-(7c) and hydroxyl-(7d) substituted bridged triarylamine helicenes were synthesized under mild conditions in 65–98% yield. Their luminescence red-shifted with π-donating substituents and blue-shifted with the electron-withdrawing CF3-substituent. The absorption and emission of the hydroxyl-substituted derivative (7d) was found to be pH-dependent, particularly under alkaline conditions. Moreover, all derivatives of 7 showed additional reversible negative redox potential, and may be useful as charge transfer materials.
Sheaf-like and layered CeO2 with micro/nanocomposite structure were synthesized by a simple and friendly hydrothermal method and used in lean methane combustion. The relationship between the CeO2 structure and catalytic performance in lean methane combustion has been studied by the means of XRD, SEM, TEM&HRTEM, H2-TPR, BET and XPS. According to the H2-TPR results, the reducibility of sheaf-like CeO2 is higher compared with layered CeO2. XPS results reveal that oxygen vacancies are more easily formed on the surface of sheaf-like CeO2 than that on layered CeO2 surface. The catalytic activity of CeO2 in lean methane combustion is strongly related to its morphology; the obtained sheaf-like CeO2 with better reducibility and larger content of Ce3+ exhibits much higher catalytic activity in lean methane combustion compared with the layered CeO2.
We have developed the synthesis of 1,3,6,8-tetramethoxy-2,7-diazapyrene through reductive aromatization of naphthalene diimide. The methoxy groups were readily converted to a variety of alkyl groups through Ni-catalyzed cross-coupling reaction with alkyl Grignard reagents. The peripheral substituents significantly influenced the packing structures of 2,7-diazapyrenes in the solid state.
Plasmonic photothermal conversion on metal nanostructures has attracted much attention because of its quick response and its local effects. In this work, we built an in-situ two-dimensional temperature measuring system with high resolution and wide temperature range to quantitatively evaluate the photothermal conversion. We analyzed carbon, Au, and Ti nanostructures. The results suggested that the photothermal conversion efficiency per unit volume was higher for plasmon resonance than that of conventional dye absorption.
A new thieno[2,3-b]thiophene-based fluorescent probe (L1) was synthesized and characterized for selective detection of Zn2+ ion at physiological pH. The probe exhibited remarkable “TURN-ON” emission in the presence of mobile Zn2+ ion. Q-TOF ESI mass spectral analysis and Job’s plot confirm 1:1 complex formation with the binding constant, Kb = 1.9 × 104 M−1. Later the 1:1 complex aggregated into a complex structure which was evident from a remarkable enhancement of fluorescence of the probe in the presence of excess of Zn2+ ions. Disodium salt of ethylenediaminetetraacetic acid (Na2H2EDTA) resulted in the TURN-OFF fluorescence of L1:Zn2+ aggregate which led us to formulate a logic-gate circuit for potential biological and material sensing.
Degradation of 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (1), a model compound for lignin β-O-4 linkage was examined with iron, ruthenium, rhodium and iridium complexes bearing cyclopentadienone ligand. Cyclopentadienone iron complex gave only a small amount of degraded product with reduced molecular weight. Cyclopentadienone ruthenium complex, so called Shvo’s catalyst, afforded 3,4-dimethoxybenzaldehyde (a3) in 14.3% yield after Cα–Cβ bond cleavage. On the other hand, cyclopentadienone group-9 metal complexes catalyzed Cβ–O bond cleavage to afford guaiacol (b1) as a main product in up to 74.9% yield.
An in situ spectroelectrochemical technique was applied to MnO2 oxygen evolution electrocatalysts with different crystal structures (α-MnO2 and β-MnO2) to monitor the Mn3+ intermediate in the presence of pyridine. Upon the addition of pyridine to the electrolyte, the UV-vis signal of Mn3+ disappeared on β-MnO2 while remaining on α-MnO2. Electrochemical and spectroscopic analysis confirmed that pyridine accelerated interfacial charge transfer between the electrolyte and the MnO2 surface by coordinating to the MnO6 octahedra, triggering more activity enhancement than α-MnO2.
Mixed valency is a well-known phenomenon in which charge distributions can change via intervalence charge transfer. In addition, there are many other ubiquitous phenomena for charges such as proton transfer, zwitterionization, charge separation, and some supramolecular interactions. However, a basic understanding of the interface between mixed valency and other charge-involved phenomena remains poor. Recent progress is described in creating mixed-valence subspecies by introducing stimuli-responsiveness to conventional mixed-valence frameworks and interplay between mobile charges and charges introduced via light and ions.
A cyclodextrin derivative 1 possessing multiple p-nitrophenylamide groups, which is a strong hydrogen-bond donor, encapsulates phosphodiester anions in two recognition modes. One is the ‘threading’ mode, in which the phosphodiester passes through the cyclodextrin cavity. The other is the ‘folding’ mode, in which the included phosphodiester is bent inside the cyclodextrin cavity. The tendency between the two recognition modes depends on the substituents on the phosphodiesters.
Benzophenone imine and its derivatives are useful ammonia equivalents for synthesizing primary amines, readily achieving the selective formation of primary amines and obtaining easily deprotectable imines as the product. These advantages have led to the development of various C–N bond-forming reactions in recent years. In this Highlight Review, we summarize the progress related to their reaction patterns.
By the thermal reaction of tetrakis(acetylacetonato)zirconium in 1,4-butanediol at 300 °C for 2 h, spherical zirconia particles with large surface areas and large pore volumes both in the meso and macro pore regions were directly obtained. The thermal reactions at lower temperatures afforded intermediate compounds having a layered-structure, attributed to the formation of the unique pore system of the products obtained in 1,4-butanediol.
The structural relaxation process has been studied for polystyrene samples by conducting physical ageing experiments. The energy barrier of the conformational transition in the isolated chain was determined to characterise the structural relaxation through the rotational potential barrier of the styrene tetramer sequence by the molecular orbital program of Gaussian, and the size of cooperative rearranging region was discussed.
Herein we report high-valency ruthenium (Ru) species as a new class of electrocatalyst for glycerol oxidation. In this study, Ru-modified covalent triazine framework (Ru-CTF) and ruthenium oxide supported on carbon (RuO2/C) were used as model materials with high-valency Ru species. The results of this work show that the deep oxidation reactions of glycerol involving C-C bond cleavage can be effectively suppressed by increasing the glycerol concentration relative to the number of active Ru atoms for both catalysts.
NiII-2,18-dibromo-20-chloroporphyrin was fused with N1,N3,N5-triaryl-1,3,5-benzenetriamine via t-BuONa-promoted one-pot reaction to give a helically twisted nitrogen-doped fused porphyrin dimer with high selectivity instead of a trimeric porphyrin. The dimer shows a red-shifted and broad electronic absorption spectrum and negatively shifted multi-stage oxidation behavior owing to the significant electronic effect of the embedded amine-type nitrogen atoms and inter-porphyrinic interaction. Bis-NiII-dimer was successfully converted to the corresponding bis-ZnII-complex, which exhibits fluorescence at around 650–700 nm.
TiO2 nanoparticles composed of rutile nanothorns and anatase nanoparticles deposited on the base of the nanothorns are obtained via a low-temperature (<100 °C) one-pot aqueous route. Heating of anatase microcapsules with rutile nanothorns which are transformed from initially formed amorphous microparticles leads disaggregation of the shell of the microcapsules in water, resulting in formation of anatase-rutile coupled TiO2. The TiO2 composite nanoparticles show functional abilities on photocatalytic reaction and soft ionization mass spectrometry.
An efficient and practical method for the synthesis of 4-aminoquinoline derivatives has been developed via copper-catalyzed cascade cyclization of 2-aminobenzonitrile and nitroolefins. This reaction proceeds through a consecutive Michael addition/cyclization/oxidization protocol, providing 4-aminoquinolines with moderate to excellent yields under mild conditions. This method features readily available materials, one-pot one-step operation, and proceeds without bases.
An anionic phthalocyanine derivative, 2,9(10),16(17),23(24)-tetrakis(carboxyl)phthalocyanine copper(II) complex (CuTCPc), exhibited G-quadruplex DNA specific binding. CuTCPc binds selectively to the 3′-terminal G-quartet, i.e., G6 G-quartet, of the all parallel-stranded tetrameric G-quadruplex of d(TTAGGG), and the specific binding of CuTCPc to the G6 G-quartet is inhibited by the addition of an extra T at the 3′-terminal of the constituent sequence, i.e., d(TTAGGGT).
Here we report SiO2@PDA@AgNP core-shell-satellite nanostructure as a new SERS substrate. This is prepared by in situ deposition of silver nanoparticles (AgNP) on the surface of polydopamine (PDA) coated silica nanoparticles (SiO2) with different sizes. The characterization of the samples along with normalization of the SERS spectra revealed a quantitative correlation between the enhancement effect of SERS and the mean diameters of the SiO2 nanoparticles. These results may provide a potential correlation between surface distribution of AgNP nanoparticles and SERS enhancement property.
The juvenile hormone (JH) is a key hormone of insects. In this study, the first structure determination of JH of Rhodnius prolixus (Heteroptera; Reduviidae) known historically as the insect for which the juvenile hormone was discovered, is reported. This species is also known as a medically important pest associated with Chagas disease. The relative and absolute stereochemistry was unambiguously determined to be methyl (2R,3S)-3-((E)-6-((R)-3,3-dimethyloxiran-2-yl)-4-methylhex-3-en-1-yl)-3-methyloxirane-2-carboxylate (JHSB3) by highly sensitive UPLC MS/MS method.
Macroscopic carbon fiber (CF) sponges were synthesized using a one-step chemical vapor deposition (CVD) method at 230 °C. The CF sponges can grow large in a single run and the yield reaches up to 2854% in 1 h without any additive. The CF sponges were self-assembled into a porous three-dimensional framework and the length of a single fiber is more than 10 µm.
Binary solvent dispersive liquid-liquid microextraction (BS-DLLME) was combined with liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS/MS) for the simultaneous determination of selected drug active compounds with high accuracy and precision. Optimization studies for the extraction parameters were carried out to lower the detection limits of seven drug active compounds. Under the optimum experimental conditions, the limits of detection (LOD) and quantitation (LOQ) values were calculated in the range of 0.01–6.1 and 0.05–20 ng mL−1, respectively. Recovery studies were also carried out with wastewater matrix to check the applicability of the developed method. The percent recovery values ranged between 95–105 and 90–116% for 75 and 125 ng mL−1 spiked samples, respectively. The recovery results obtained established the applicability of the developed method for the quantification of all analytes in the selected matrix. Thus, the developed method can be used for the simultaneous determination of analytes with high accuracy and precision.
Optically active (S)-(+)- and (R)-(−)-10,10′-spirobi[10H-phenoxasilin]-1,1′-diols were synthesized by the transesterification of their optically active di-p-toluoyl derivatives resolved by chiral HPLC. The absolute configurations of the optically active spirosilanes were elucidated by single-crystal X-ray structural analysis. Phosphoramidite derivatives of the optically active diols were applied to Pd-catalyzed asymmetric allylic amination using 1,3-diphenylallyl acetate and benzylamine with moderate enantioselectivity.
This paper reviews the rate constant matrix contraction (RCMC) method, a kinetics-based graph clustering approach developed for the network of paths of chemical reaction elementary steps. First, fundamentals of the transition state theory and the concept and algorithm of the RCMC method are introduced. Next, the RCMC method is explained for kinetic simulation and kinetics-based navigation of automated reaction path search. The RCMC-based kinetic simulation enables quick evaluation of population of chemical species involved at a specific time without explicit time-evolution of the rate equations. The kinetics-based navigation combined with the single component artificial force induced reaction (SC-AFIR) method dramatically reduces the cost of SC-AFIR searches by restricting the search areas to those that are kinetically accessible from the initial structure under a given reaction temperature and timescale. These approaches are presented together with some example applications.
Several fabrication technologies for molecular level ultra-thin films, from organic to organic–inorganic hybrids, are introduced using the surface imaging technology of scanning probe microscopy (SPM). Electrochemical scanning tunneling microscopy (EC-STM), atomic force microscopy (AFM) and related techniques enable the observation of the surface of 2D materials in near real-time and in real-space. The combination of 2D materials and SPM technology opens up a new avenue of surface and material science, despite its many restrictions.
Head-to-tail dipole-dipole arrays of isoxazole rings lead to supramolecular helical assemblies where the assembly and disassembly are regulable based on temperature and solvent properties. The cooperative supramolecular polymerization characterized by a two-step polymerization consisting of nucleation and elongation is driven by the multiple dipole array as well as the induced dipoles in the supramolecular organization. The helical supramolecular assemblies are fabricated with the aid of multiple dipole–dipole interactions. The chiroptical properties, such as CD and CPL, are determined by the right-handed and left-handed helicities of the supramolecular organizations, which are directed by the stereogenic side chains. The AIE and AIEE are established in the supramolecular assemblies. The AIE feature of the platinum complex is inherent in the supramolecular assemblies, which results in luminogenic micelles. Emissive supramolecular micelles are fabricated. In this review, these aspects are briefly described, emphasizing the importance of the intermolecular dipole-dipole interactions in supramolecular chemistry.
This study reports a facile and green preparation of heteroatom-doped porous carbon nanosheets derived from deep eutectic solvents (DES). N-doped or N, S-co-doped carbon porous nanosheets are produced by varying the composition of glucose-based DES followed by a simple KOH activation, which show highly improved capacitances. Besides, micro-supercapacitors based on N-doped carbon nanosheets exhibit a specific capacitance of 23.2 mF cm−2 at 0.2 mA cm−2, which is among the best compared to the results reported in the literature.
Conjugated bisbutatrienes 1a–f with an acenaphthene backbone were synthesized and characterized. The conjugated cumulene moiety worked well as a starting point for the construction of polycyclic conjugated hydrocarbons. The cycloisomerization of 1 catalyzed by Ga(III) and In(III) salts directly gave the diareno[a,f]pentalene framework 6.
Novel synthetic methods for phenoxathiins and phenothiazines by aryne reactions are disclosed. We found that phenoxathiins were efficiently prepared by the reaction between aryne intermediates and S-(2-hydroxyaryl) 4-toluenethiosulfonates. A synthetic method for phenothiazines was also developed by the reaction of arynes with S-(2-aminoaryl) 4-toluenethiosulfonates.