Latest ArticlesTwo isostructural Ni(Ⅱ)/Co(Ⅱ)-based metal-organic frameworks (MOFs), namely {[M3(L)2(bpb)3(H2O)4]·2DMF·2H2O}n [M = Ni (HL-5, HL is short for Hui-Ling Liu); M = Co (HL-6); H3L = 2', 6'-dimethyl-[1, 1'-biphenyl]-3, 4', 5-tricarboxylic acid; bpb = 1, 4-bis(pyrid-4-yl)benzene], have been hydrothermally syn-thesized and structurally characterized. Both HL-5 and HL-6, which have the same three-interpenetrated 3D pillared-layer framework with sqc306 type topology, present good selective methyl orange (MO) adsorption over rhodamine B (RhB). Moreover, the catalytic CO2 cycloaddition properties with epoxides of the two MOFs have also been studied at ambient pressure and temperature.
Both racemate and enantiomer of a novel double helix, binaphthylcyclooctaterthiophene (BN—COTh), which is a DNA-like molecule constructed by two single helices intertwined with each other via covalent bonds, have been synthesized with two building blocks, cycloocta-tetrathiophene (COTh) and cyclooctadinaphthyldithiophene (CONT) fused together via Negishi coupling reaction. Another homologue, dinaphthylcyclooctaterthiophene (DN-COTh) has been employed together as a model compound. Besides the synthetic work, BN—COTh and DN-COTh have been investigated by studying their crystal structures, spectroscopic behaviors, chiral resolution and chiral characteristics, including circular dichroism (CD) spectra and optical rotations. In addition, the novel crystal of enantiomer of (R, R, R)-BN—COTh has been explored. The enantiomer molecules packing along b-axis to form a larger and extended assembly packing due to intermolecular interactions between the enantiomer molecules and chloroform molecules in crystal.
We studied the cascade nucleophilic addition reactions of 1,2,3-triazines with activated acetonitriles or ketones, which were used to construct highly substituted pyridines that are not easily accessed by conventional methods. The strategy addressed some structural diversity issues currently facing medicinal chemistry, and the resulting pyridines could be used as convenient precursors for the synthesis of related pharmaceuticals. In particular, our method was applied to the syntheses of the marketed drug etoricoxib and several biologically important molecules in a few steps.
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.
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.
Graphene nanosheets are widely used in anti-corrosion polymeric coating as filler, owing to the excellent electrochemical inertness and barrier property. However, as the arrangement of graphene nanosheets is difficult to form a perfect layered structure, polymeric coating with graphene nanosheets usually needs micron-scale thickness to ensure the enhancement of corrosion protection. In this work, layer-by-layer stacked graphene nanocoatings were fabricated on stainless steel by self-assembly based on Marangoni effect. The anti-corrosion property of graphene coatings were studied through Tafel polarization curves, electrochemical impedance spectroscopy and accelerated corrosion test with extra applied voltage. The self corrosion current density of optimized three-layered graphene coated sample was one quarter of that of bare stainless steel. And the self corrosion potential of optimized sample is increased to -0.045 V. According to the results, graphene nanocoatings composed of layered nanosheets exhibits good anti-corrosion property. Besides, the self-assembly method provide a promising approach to make layered-structure coating for other researches about 2D material nanosheets.
In this communication, a new supramolecualr amphiphile was successfully constructed based on water soluble pillar[5]arene and a unique guest which contain a CO2 responsive tertiary amine unit and a UV responsive coumarin group. When guest molecule 1 dispersed in water, it self-assembled into sheet-like structures. Upon bubbling CO2, 1 transformed into 1H due to the tertiary amine unit was protonated, accompany the nano-sheets transformed into vesicles. Further irradiation of 1H with 365 nm light for 3 h, the coumarin group reacted with each other to form bola-type amphiphie 2H. In this case, vesicles collapsed and re-assembled into nano-tubes. However, when addition of WP5 into the solution of 1H, the vesicles transformed into micelles, this is due to the formation of supramolecular amphiphile WP5&1H. Upon irradiation of WP5&1H with 365 nm light for 3 h, nano-ribbons observed instead of micelles in the solution. Notably, nanotubes from 2H could also transform into nano-ribbons after adding WP5. The self-assembly process and the resultant assemblies were characterized by TEM, SEM, DLS, SAXS and NMR technologies. Due to both CO2 and light are pgreenq for living organisms, we anticipated our system can offer the possibilities in pon demandq drug absorption and release.
A metal-organic photoinduced electron transfer (PET) supramolecular nanoarchitecture comprised of Ru(Ⅱ) bis(terpyridine)-modified pillar[5]arene (electron acceptor) and triazole triphenylamine amyl cyanide (electron donor) has been designed and constructed. Through the comparison of diverse solvents and acceptors, the two conditions, i.e., modification of pillar[5]arene to donor and weak polar solvent are benefit for the occurrence of "efficient PET" because of shorter D-A distance in the presence of pillar[5]arene. Crucially, the fluorescence and PET process of the supramolecular assembly could be further modulated by solvent conversion and another competitive guest. The study provides a supramolecular method to design and construct tunable PET systems and PET-based smart materials.
A pyrene-tiaraed pillar[5]arene derivative was synthesized, which showed a concentration-independent intensive excimer emission. Photolysis of the pyrene-tiaraed pillar[5]arene led to a switch from excimer to monomer emission, applicable to photo-writing.
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