Latest ArticlesThe cascade reactions of alkyl α-diazoesters and ynones using Al(OTf)3 as the catalyst are described. A series of 4-substituted pyrazoles were obtained via [3 + 2] cycloaddition, 1, 5-ester shift, 1, 3-H shift, and N—H insertion process. Deuterium labelling experiments, kinetic studies and control experiments were carried out for the rationalization of the mechanism.
Traditional matrix does not allow matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) to analyze volatile compounds, because volatile analytes may vaporize during the sample preparation process or in the high vacuum circumstance of ion source. Herein, we reported a Co and N doped porous carbon material (Co-NC) which were synthesized by pyrolysis of a Schiff base coordination compound. Co-NC could simultaneously act as adsorbent of volatile compounds and as matrix of MALDI MS, to provide the capability of MALDI MS to analyze volatile compounds. As adsorbent, Co-NC could strongly adsorb and enrich the volatile compounds in perfume and herbs, and hold them even in the high vacuum circumstance. On the other hand, Co-NC could absorb the energy of the laser, and then transfer the energy to the analyte for desorption and ionization of analyte in both negative and positive ionization modes. Additionally, the background interferences were avoided in the low-mass region (< 500 Da) when using Co-NC as matrix, overcoming the challenges of MALDI MS analysis of small molecule compounds. In summary, Co-NC as matrix tremendously extended the application of MALDI MS.
A wide variety of molecular probes have been developed for real-time analysis, but most of organic fluorophores possess small Stokes shifts and self-absorption or inner filter effect that could not be avoided. In this study, a new dicyanoisophorone-based derivative (E)-O-(4-(2-(3-(dicyanomethylene)-5, 5-dimethylcyclohex-1-en-1-yl)vinyl)phenyl)diphenylphosphinothioate (λex = 405 nm, λem = 551 nm, denoted as ICM-S) with strong push-pull electron effect has been afforded and it exhibits red shift for absorption from 407 nm to 426 nm with distinct color change from pale yellow to deep yellow upon exposure to Hg2+. Moreover, an easily distinguishable fluorescence color change follows the route from green, yellow to red in the presence of Hg2+ over the range of 0-90 μmol/L (detection limit = 137 nmol/L) can be observed by the naked eye under a UV lamp irradiation. Chlorodiphenylphosphine and sublimed-sulfur are incorporated as responsive sites and P-O bond has been cleaved upon the addition of mercury ions. During the recognition process, such dicyanoisophorone dye (ICM-S) has been evolved to 2-(3-(4-hydroxystyryl)-5, 5-dimethylcyclohex-2-enylidene) malononitrile (ICM OH). Clear evidences in the chemical processes can be identified via single crystal X-ray diffraction, spectroscopic analysis, photophysical studies and titration experiments. With the aim of exploring its potential in biological systems, its in vitro responses to Hg2+ have been evaluated in 293 Tcells and the effectiveness in zebrafish model has also been verified.
A simple method to synthesize luminescent λ5-phosphanaphthalenes and zwitterionic nido-carborane fused six-membered phosphacycles was developed from the reaction of ortho-phosphinobenzoalde-hydes or ortho-phosphinocarboranylaldehydes with an electron-deficient alkyne, respectively. Similar results were obtained with the imino analogues.
SnO2 is considered a promising anode material for sodium-ion batteries due to its high theoretical capacity and low cost. However, the poor electrical conductivity and dramatic volume variation during charge/discharge cycling is a major limitation in its practical applicability. Here we propose a simple one-pot spray pyrolysis process to construct unique pomegranate-like SnO2/rGO/Se spheres. The ideal structural configuration of these architectures was effective in alleviating the large volume variation of SnO2, besides facilitating rapid electron transfer, allowing the devised anode to exhibit superior sodium storage performances in terms of capacity (506.7 mAh/g at 30 mA/g), cycle performance (397 mAh/g after 100 cycles at 50 mA/g) and rate capability (188.9 mAh/g at an ultrahigh current density of 10 A/g). The experimental evidence confirms the practical workability of p-SnO2/rGO/Se spheres in SIBs.
Density functional theory calculations have been performed to investigate the copper-catalyzed borocyanation of 1-aryl-1,3-butadienes. The computations show that the regio- and enantioselectivity is determined by the borocupration step. The π-electron withdrawing aryl group at the C1 atom makes the C4 atom more electrophilic than the other carbon atoms, which together with the steric repulsion around the forming C—B bond, results in the experimentally observed exclusive 4,3-regioselectivity. The origins of the enantioselectivity were attributed to the steric effect and π-π stacking interaction between the butadiene moiety and the ligand.
Smart materials, such as stimuli-responsive luminescence, have attracted much attentions due to their potential application in semiconductorfiled. In this context, platinumcomplexes of (dfppy-DC)Pt(acac) and (dfppy-O-DC)Pt(acac) were prepared and characterized, in which (2-(4', 6'-difluorophenyl)pyridinato-N, C2')(2,4-pentanedionato-O, O)Pt(Ⅱ) was used as the planar emission core and 9-(4-(phenylsulfonyl) phenyl)-9H-carbazole (DC) was regard as the bent pendent. Both platinum complexes showed bright emission in solution and solid state, concomitant with charming external-stimuli-responsive emission under mechanical grinding, organic solvent vapors and pressure. The change emission color spanned from yellow to near-infrared region. Using the platinum complexes as the dopant, solution processable organic light-emitting diodes (OLEDs) were fabricated and a maximum external quantum efficiency of ~18% was achieved, which is the highest value among the reported solution-processable OLEDs based on external-stimuli-responsive luminescence.This research demonstrated that platinum complex can show promising stimuli responsive emission via ingenious molecular design, indicating a novel way for developing the smart materials in semiconductor filed.
Curcurbit[n]uril (Q[n])-based supramolecular frameworks (QSFs) constructed from the outer surface interaction of Q[n]s (OSIQ) have the characteristic of simplicity, diversity and modulability. Their simplicity is reflected in their simple composition and preparation methods used for QSFs. The diversity of supramolecular organic frameworks (SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs, as well as the variety of structural directing agents and basic building blocks used to prepare QSFs. The modulability is reflected by the controllable channel size in the QSFs, which can be adjusted using different sizes of Q[n]s. In this work, the first reported cucurbituril Q[6] was selected as the basic building block and three Q[6]-based supramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl4]2- respectively. The OSIQs are the main driving forces for the formation of these frameworks. This study shows the diversity of the QSFs.
Flat and crystalline materials with exceptional nonlinear optical (NLO) properties are highly desirable for their potential applications in integrated NLO photonic devices. Graphdiyne (GD), a new two-dimensional (2D) carbon allotrope, has recently evoked burgeoning research attention by virtue of its tunable bandgap along with a high carrier mobility and extended π-conjugation compared with most conventional optical materials. Here, we experimentally probe the third-order nonlinear optical response of GD dispersed in several common solvents (alcohols) using a femtosecond Z-scan technique. The measured nonlinear optical refractive index is in the order of ~10-8 cm2/W, which is approximately one order of magnitude higher than that of most 2D materials. In particular, we find that different NLO responses can be observed from GD when dispersed in different solvents, with the strongest NLO response when dispersed in 1-propanol. It is proposed that some intrinsic properties of the solvents, such as the polarity and viscosity, could influence the NLO response of GD materials. Our experimental results confirm the assumptions on the NLO behavior in GD and demonstrate its great potential for future generations of Kerr-effect-based NLO materials and devices.
RuPt/AC bimetallic catalysts were prepared by two-step incipient impregnation method and evaluated in the hydrogenation of phthalates. According to the characterization results, well dispersed RuPt bimetallic nanoparticles were formed on the catalyst, and the strong interaction between the two metals resulted in the formation of RuPt alloy. It was found that Ru can donate electrons to Pt on RuPt alloy nanoparticles, leading to the formation of electron-deficient Ru which significantly promotes the hydrogenation rate of dioctyl phthalate and improves the selectivity of dioctyl di-2-ethylhexylcyclohexane-1, 4-dicarboxylate by accelerating the further hydrogenation of intermediate products. The bimetallic RuPt catalyst also presented excellent stability and versatility in the hydrogenation of phthalates, demonstrating its prospective future in the hydrogenation of aromatic ring contained compounds.
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