Search

The tail of imidazole regulated the assembly of fascinating 2D sql topology and 3D 2-fold interpenetrated lvt structure polyoxotungstate-based open frameworks with efficient visible-white-light-driven aerobic catalytic oxidation of sulfides.

A robust and porous Ti-MOF, LCU-402, shows permanent porosity for CO2, CH4, C2H2, C2H4, and C2H6 gas adsorption, and can smoothly convert CO2 into organic carbonate molecules by cycloaddition of epoxides with CO2 in simulated flue gas.

Three imidazole-modified Ag-polyoxovanadates frameworks (APFs) with a controllable molar ratio of Ag+ to polyoxovanadates (POVs) [Ag(IM)2]2V4O12∙2Ag(IM)2 (APF-1), [Ag2(1-eIM)4]2[Ag(1-eIM)2]3∙2Ag(1-eIM)2∙3(1-HeIM)[V10O28]2 (APF-2) and [Ag(1-pIM)2]3[HV10O28]∙2Ag(1-pIM)2∙2H2O (APF-3) (IM = imidazole; 1-eIM = 1-ethylimidazole and 1-pIM = 1-propylimidazole) have been successfully achieved by self-assembly of POVs, Ag+ cations, and three different imidazole derivatives. Interestingly, the molar ratios of Ag+ to POVs vary from 4:1, 4.5:1 to 5:1 by changing the vanadium resources and imidazole derivatives. Notably, the coordination environment of Ag+ cations and the structure of POVs in the APFs are also different. Specifically, for APF-1, the four Ag atoms adopt three-coordinated and four-coordinated geometries, respectively, and Ag-imidazole complexes and [V4O12]4− cluster form the one-dimensional polymeric chains. While Ag atoms in APF-2 and APF-3 exhibit two-, four- and five-coordinated geometries for APF-2, four-, five- and six-coordinated geometries for APF-3, respectively. These Ag+ cations and decavanadate clusters are assembled into the 2D supramolecular structure through the Ag-O bonds and Ag…Ag argentophilic interaction. Remarkably, thus-obtained APF-2 can serve as powerful efficient heterogeneous catalyst for construction of C-N bond and detoxification of simulant sulfur mustard (yields up to 99%), which enable successful recycling for three cycles with remained catalytic activities and structure stability.

A family of microporous and acid–base Ln-MOFs (1-Ln, Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) has been synthesized from the H3NTB ligand. 1-Ln can efficiently catalyze both cycloaddition of epoxides with CO2 and one-pot cascade deacetalization–Knoevenagel reactions.

A facile one-step ball-milling strategy to prepare gram-scale Mg3Al-LDH-Nb6 has been demonstrated and the thus-obtained catalyst exhibited efficient selective catalytic activities in the synthesis of biologically active organic molecules in water.

The selective oxidation of amines into imines is a priority research topic in organic synthesis and has attracted much attention over the past few decades. However, the oxidation of amines generally suffers from the drawback of transition-metal, even noble-metal catalysts. Thus, the strategy of metal- and oxidant-free selective synthesis of imines is highly desirable yet largely unmet. This paper unravels a metal-free and external oxidant-free electrochemical strategy for the oxidative coupling methodology of amines. This general transformation is compatible with various functional amines and led to functionalized imines in moderate to satisfactory yields.

A condition-controlled strategy for selectively synthesis of 2-acylbenzothiazoles and bibenzo[b][1,4]thiazines from aryl methyl ketones and disulfanediyldianilines was realized using I2/DMSO or I2/MeCN systems, respectively. The desired products were synthesized in only 15 min with moderate to excellent yields (50%-90%) under microwave-assisted, metal-free conditions. The strategy provides a great advantage for selective synthetic applications in the efficient synthesis of benzothiazoles and bibenzothiazines heterocycle compounds.

Four transition-metal lacunary polyoxometalates (TM-LPOMs, TM = Cu, Co, Ni, and Mn) are prepared and fabricated into ultralow density LPOM-based foams (LPOMs@CMC) for the efficient flowing catalytic production of sulfenamide additives.

Guided by a second-sphere interaction strategy, we fabricated a Tb(III)-based metal-organic framework (MMCF-4) for turn-on sensing of methyl amine with ultra-low detection limit and high turn-on efficiency. MMCF-4 features lanthanide nodes shielded in a nonacoordinate geometry along with secondary coordination spheres that are densely populated with H-bond interacting sites. Nonradiative routes were inhibited by binding-induced rigidification of the ligand on the second coordination sphere, resulting in luminescence amplification. Such remote interacting mechanism involved in the turn-on sensing event was confirmed by single-crystal X-ray diffraction and molecular dynamic simulation studies. The design of both primary and secondary coordination spheres of Tb(III) enabled the first turn-on sensing of organic amines in aqueous conditions. Our work suggests a promising strategy for high-performance turn-on sensing for Ln-MOFs and luminous materials driven by other metal chromophores.

At present, shield tunneling often needs to pass through a large number of bridge pile foundations. However, there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage. Based on Winkler model, the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived. Meanwhile, full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement, ground surface settlement trough, vertical and horizontal displacement of the pile and pile stress under three calculation conditions, i.e., not considering groundwater effect, considering stable groundwater effect and fluid-soil interaction. The results show that the calculated value is small when the effect of groundwater is not considered; the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction, and after the shield passing, the groundwater on both sides shows a flow trend of “U” shape on the ground surface supplying to the upper part of the tunnel; the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel, the upper pile body settles, and the lower pile body deforms upward. The horizontal displacement of pile body presents a continuous “S” shape distribution, causing stress concentration near the tunnel. The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.

A family of microporous and robust Ln(iii)-based metal-organic frameworks (1-Ln, Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) have been obtained using 4,4',4''-nitrilotribenzoic acid (H

Two concise strategies to synthesize oxazolidin-2-imines by cascade nucleophilic attack/addition cyclization reactions of (

Simple reaction conditions and recyclable reagents are crucial for environmentally friendly industrial applications. An environment-friendly, recyclable and economic strategy was developed to synthesize diaryl chalcogenides by the CuCl2-catalyzed C–S bond-formation reaction via iodobenzenes and benzenethiols/1,2-diphenyldisulfanes using N,N′-dimethylethane-1,2-diamine (DMEDA) as ligand, base, and solvent. For these reactions, especially the reactions of diiodobenzenes and aminobenzenethiols/disulfanediyldianilines, a range of substrates are compatible and give the corresponding products in good to excellent yields. Both of the reagents in the catalytic system (CuCl2/DMEDA) are inexpensive, conveniently separable, and recyclable for more than five cycles.

Summary γ-butyrolactone (γ-BL), serving as the monomer of biocompatible and recyclable poly(γ-butyrolactone) plastic, faces a giant challenge in ring-opening polymerization (ROP) due to its low strain energy. The ROP of γ-BL is generally achieved under harsh conditions (e.g., high-pressure or gas-protected atmosphere) and is mostly based on homogeneous systems. Here, we synthesize a series of lanthanum metal-organic framework-based porous nanospheres and successfully apply them as heterogeneous catalysts in efficient ROP of γ-BL under mild conditions. Specifically, NNU-mIM-3 presents a yield of 24.6% with low polydispersity distribution centered at 3.6 kDa and the obtained PγBL can be completely and quantitatively recycled into monomers by simple heat treatment. Besides, the ROP catalysis systems have been intensively explored with various imine-based additives, proven to exhibit largely improved performance with PγBL yield of ~50% and Mw of ~8 kDa. This work paves a new way to explore novel heterogeneous catalysts in producing biocompatible and degradable plastics.

By introducing 4-amino-1,2,4-triazole (4-NH2-trz), three new polyoxovanadate-based metal-organic frameworks (PMOFs) [Ni3(4-NH2-trz)6][V6O18]·3H2O (1), [Co3(4-NH2-trz)6][V6O18]·3H2O (2) and [Cu3OH(4-NH2-trz)3H2O][VO3]5·H2O (3) have been synthesized and thoroughly characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis and elemental analysis (EA). Among them, PMOFs 1 and 2 had similar structures containing [V6O18]6- clusters; however, PMOF 3 was isolated as a structure containing a [VO3]55- cluster when the amount of the 4-NH2-trz ligand was reduced to half with the other synthesis conditions being the same as those of PMOFs 1 and 2 except for the transition-metal chlorides. Furthermore, the negative charges of polyoxovanadate [V6O18]6- and [VO3]55- anions were balanced by trinuclear complex cations [Ni3(4-NH2-trz)6]6- for 1, [Co3(4-NH2-trz)6]6- for 2 and [Cu3OH(4-NH2-trz)3H2O]5- for 3, respectively. PMOFs 1-3 were further used as heterogeneous catalysts in the Knoevenagel condensation under solvent-free conditions and showed high catalytic activity. PMOF 1 showed moderate catalytic activities in the oxidation of various aromatic alcohols using H2O2 as an oxidant. Moreover, PMOF 1 could be reused at least three times without losing its activity.

An addition of H-phosphonates to aryl alkynes was realized under solvent- and metal-free conditions, affording Markovnikov-selective α-vinylphosphonates in moderate to good yields. A wide range of aryl alkynes could be applied for the reaction. A tentative mechanism of addition–substitution was proposed based on in situ 31P {1H} NMR studies.

A method for the synthesis of fused chromeno quinolines by the palladium/copper cocatalyzed C-H bond activation and C-C bond cleavage reaction has been developed. A variety of fused chromeno quinoline derivatives could be synthesized by coumarin derivatives and anilines through the C-C bond cleavage/C-H functionalization/C-C bond formation process. The MTT assay was used to evaluate the chromeno quinolines against the human cervix tumor cells (HeLa), 3c and 9c without coordination metals showed good inhibition effect.

Polyoxometalates (POMs) is a kind of metal-oxygen clusters with well-defined structures, controllable composition, and excellent properties including acidity, redox properties, etc . In recent years, POMs have shown potential application in the field of catalysis, materials, energy conversion and pharmaceuticals and become a hot interdisciplinary research area. This review focuses on the recent progress in the structure design of POMs and their catalytic properties, mainly including POM structure chemistry, acid-base catalysis, redox catalysis, photocatalysis, the catalytic conversion of CO2 and toxic molecules. In addition, the future development of POMs-based catalysis is prospected.

Ti3C2 belongs to MXenes family, which is a new two-dimensional material and has been applied in many fields. With simple method of hydrothermal and high temperature calcination, nanostructured Ni/Ti3C2Tx hybrid was synthesized. The stable layer structure of Ti3C2 MXene providing high surface area as well as excellent electronic conductivity are beneficial for deposition and decomposition of discharge product Li2O2. Furthermore, possessing special catalytic activity, Ni nanoparticles with size of about 20 nm could accelerate Li2O2 breaking down. Taking advantage of two kinds of materials, Ni/Ti3C2Tx hybrid as cathode of Li-O2 battery can achieve a maximal specific capacity of 20,264 mAh/g in 100 mA/g and 10,699 mAh/g in 500 mA/g at the first cycle. This work confirms that the prepared Ni/Ti3C2Tx hybrid exhibiting better cycling stability points out a new guideline to improve the electrochemical performance of lithium-oxygen batteries.

Two-dimensional MXene with high conductivity has metastable Ti atoms and inert functional groups on the surface, greatly limiting application in surface-related electrocatalytic reactions. A surface-functionalized nitrogen-doped two-dimensional TiO

A series of microporous Ln(III)-based metal–organic frameworks (1-Ln) have been hydrothermally synthesized using 4,4′,4′′-nitrilotribenzoic acid (H3NTB). Single crystal X-ray diffraction analyses show that 1-Ln are isostructural and have 3D porous frameworks with remarkable stability and permanent porosity for Ar and CO2 adsorption. In addition, 1-Ln exhibit diverse photoluminescence emissions depending on the nature of lanthanide ions. More importantly, 1-Ln are further studied in the Knoevenagel reactions of benzaldehyde derivatives and malononitrile under solvent-free conditions, and it is found that 1-Tb shows the best catalytic activities (yields up to 99%), providing a unique example to differentiate the roles of Ln ions within the frameworks in catalyzing Knoevenagel reactions.

We reported an economic and practical ball-milling method for the synthesis of tetrahydroquinoline derivatives via a ‘one-pot’ three-component Diels-Alder reaction of anilines, aldehydes and alkenes catalyzed by phosphotungstic acid at room temperature. For this reaction, a simple “one-pot” ball-milling operation was conducted, readily available starting materials were employed, ‘one-pot’ conditions were applied, and the most important was to use inexpensive and environmentally friendly catalyst phosphotungstic acid. Various tetrahydroquinolines, which might be potentially applicable in the pharmaceutical and biochemical areas, were conveniently synthesized in moderate to excellent yields.

One bonded- and one discreted-Lindqvist hexatungstate-based copper hybrids (Cu-POMs) ([Cu2(O)OH(phen)2]2[W6O19]·6H2O (1) and [Cu2(phen)4Cl] [HW6O19]·2H2O (2) (phen = 1,10-phenanthroline)) were controllably synthesized and routinely characterized. Cu-POMs 1–2 consisted of identical [W6O19] unit and similar copper–phen complexes, the two units are bonded via four Cu–O chemical bonds in compound 1; however, compound 2 is discreted and stabilized by intermolecular electrostatic interactions. Importantly, these Cu-POMs catalysts were first applied in the novel reaction for the preparation of 2-phenylquinoxalines via the one-pot coupling and oxidation reactions of 2-haloanilines with vinyl azides or 3-phenyl-2H-azirines under mild conditions, and Cu-POMs 1 showed higher catalytic performance in good yields (79–84%). The reactions exhibit some functional group tolerance and allow for the preparation of a number of 2-phenylquinoxalines.

By rationally controlling hydrothermal conditions, three new inorganic–organic hybrid polyoxovanadates (POVs) [Ni2(1-vIM)7H2O][V4O12]·H2O (1), [Cu2(1-vIM)8][V4O12]·H2O (2) and [Co(1-vIM)H2O][VO3]2 (3) (1-vIM = 1-vinylimidazole) have been synthesized and thoroughly characterized by single X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR), and elemental analyses (EA). Interestingly, complexes 1 and 2 have similar structures including [V4O12]4− clusters; complex 3, however, was isolated as a structure by including the [VO3]22− cluster under a different synthetic condition compared with those of 1 and 2. Both complexes 1 and 2 display an interesting 3D supramolecular structure, and complex 3 shows a 2D two parallel networks supramolecular structure linked by a [Co2O2] unit due to the different coordination environments of the central metals. Three inorganic–organic hybrid POVs as heterogeneous catalysts are active in the selective oxidation of sulfides to produce sulfoxides or sulfones with high conversion and high selectivity (up to 99.5% for sulfoxides and 98.5% for sulfones respectively catalyzed by 1). Complex 1 is also used as catalyst in the oxidative CEES (2-chloroethyl ethyl sulfide, a sulfur mustard simulant) abatement with high activity and selectivity toward the corresponding sulfoxide. Moreover, complex 1 can be reused at least three times in sulfoxidation reactions without losing its activity.

Polyester plastics such as poly(ethylene terephthalate) (PET) are utilized commonly in everyday life, yet only a small portion of these plastics are recycled, and typically, the recycling procedure...

The synthesis of two sulfur-decorated perylene diimides, the five-membered S-heterocyclic annulated perylene diimide (1) and 1-propanethiol- N,N′-dicyclohexylperylene-3,4,9,10-tetracarboxylic diimide (2), and a novel sulfoxide-containing perylene diimide, 1-propyl sulfoxide- N,N′-dicyclohexylperylene-3,4,9,10-tetracarboxylic diimide (3), are reported. The photophysical, electrochemical, aggregation, and thermal properties of these compounds are investigated by ultraviolet visible absorption, fluorescence, cyclic voltammetric, X-ray diffraction, and thermogravimetric analysis techniques. The geometries of the compounds are optimized at the 6-31G* level of theory using density functional theory, and their potentials are correlated with molecular orbitals. The prepared perylene diimide derivatives exhibit narrow the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals band gaps, and they have quite different absorptions and emissions in dichloromethane solutions, which are in agreement with the density functional theory–calculated results.

A sulfur-decorated perylene derivative, 1-propanethiol-N,N′-dicyclohexyl perylene-3,4,9,10 tetracarboxylic diimide (PTPDI), was synthesized and fully characterized by 1H NMR, 13C NMR, FTIR, HRMS, UV–vis absorption, fluorescence, fluorescence lifetime, fluorescence quantum yield, cyclic voltammetry, and thermogravimetric techniques. The optical, fluorescence, and scanning electron microscopies were employed to study its self-assembly process. The photophysical properties were affected strongly by modifying the propanethiol unit linking to the perylene core. Furthermore, the chromophore showed two irreversible oxidations and two quasi-reversible reductions in dichloromethane at modest potential. The optical properties of PTPDI in various conditions and complementary density functional theory calculations were reported. Due to steric hindrance of the bulky n-propyl mercaptan substituent, PTPDI molecules are arranged in slipped face-to-face fashion to form J-aggregates. Thus, the intermolecular π–π actions of the molecule are weak, causing its high luminescence efficiency. In the meantime, the space between perylene cores is very short (3.45 Å), which is favorable for the hopping transportation of charge carrier from one molecule to an adjacent one. PTPDI could be a candidate material for acquiring a well-defined organic nanostructure with excellent charge-transporting and light-emitting capabilities.

Four new mixed-valence manganese complexes, [Mn(II)Mn(III)2(S-L1)2(OAc)4]·2H2O(1), [Mn(II)Mn(III)2(R-L1)2(OAc)4]·2H2O (2), [Mn(II)Mn(III)2(2H2O)(S-L2)2(OAc)4] (3), [Mn(II)Mn(III)2(2H2O)(R-L2)2(OAc)4] (4) [H2L1 derived from (R)/(S)-2-amino-1-butanol and 2-hydroxy-5-chlorobenzaldehyde, H2L2 derived from (R)/(S)-2-amino-3-phenyl-1-propanol and 2-hydroxy-4-methoxybenzaldehyde], were synthesized and fully characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. Complexes 1–4 are mixed-valence trinuclear manganese compounds with six-coordinated. The linear MnIII–MnII–MnIII cores are triply bridged by acetate, phenolate and alkoxy groups. The vitro cytotoxicity test revealed that all complexes have substantial cytotoxic activity against three cancer cell lines (HepG2, MDA-MB-231 and A549). DNA-binding properties of 1–4 were investigated by UV–Vis, fluorescence spectroscopy, viscosity and thermal denaturation. All complexes bound to calf thymus DNA (CT-DNA) via an intercalative mode, and that derived from (S)-Schiff base ligands exhibited stronger interaction with DNA than (R)-isomers. Furthermore, the interactions of 1–4 with bovine serum albumins (BSA) in a static mode were also studied using absorption emission spectral techniques and molecular docking analysis. The chirality and structure of ligands showed to a large influence on the DNA/BSA binding ability and cytotoxicity of manganese complexes. The geometry optimization results are in agreement with experimental observations.

LaSrNiO nanoparticles with different doping amount of strontium are synthesized through sol-gel method accompanied by high-temperature calcination. With the increase of Sr content, the crystal structure of samples changes from perovskite to spinel phase that promote both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) property. As a cathode catalyst for Li-O2 battery, LaSrNiO nanoparticles show a capacity performance of 9000 mAh·g−1 and significantly enhanced cyclability. The improved battery performance with Sr-doped nanoparticles can be ascribed to the high surface area of Sr-doped LaSrNiO nanoparticles combined with mixed spinel and perovskite phased structure which facilitate specific capacity and OER performance obviously. This research work is believed to shed light on a new thought to boost the performance of Li-O2 battery.

Guided by a second-sphere interaction strategy, we fabricated a Tb(III)-based metal-organic framework (MMCF-4) for turn-on sensing of methyl amine with ultra-low detection limit and high turn-on efficiency. MMCF-4 features lanthanide nodes shielded in a nonacoordinate geometry along with secondary coordination spheres that are densely populated with H-bond interacting sites. Nonradiative routes were inhibited by binding-induced rigidification of the ligand on the second coordination sphere, resulting in luminescence amplification. Such remote interacting mechanism involved in the turn-on sensing event was confirmed by single-crystal X-ray diffraction and molecular dynamic simulation studies. The design of both primary and secondary coordination spheres of Tb(III) enabled the first turn-on sensing of organic amines in aqueous conditions. Our work suggests a promising strategy for high-performance turn-on sensing for Ln-MOFs and luminous materials driven by other metal chromophores.

Isolation piles are widely used to control the influence of shield tunnelling on adjacent buildings as an effective protective measure. However, the restraint effect of isolation pile on surface settlement trough is rarely explored from the internal mechanism. Firstly, the restraint mechanism of isolation piles is investigated from the pile-soil-tunnel interaction mechanism. Secondly, based on the Melan solution and the Loganathan formula, the analytical solution of surface settlement trough under the influence of adjacent isolation piles is derived. Thirdly, in order to satisfy the engineering analysis scale and reflect the friction characteristics between isolation pile and soil particles simultaneously, the FDM-DEM coupling technique is introduced to establish a numerical model including discrete medium and continuum medium. Finally, the applicability and reliability of the analytical solution and the FDM-DEM coupling numerical solution are verified by comparing field measured data. The results indicate that the surface settlement trough under the influence of isolation piles will have an asymmetric distribution. Surface settlement tends to develop more to the opposite side of the tunnel when isolation piles are pre-installed on one side. The findings of the study have substantial theoretical significance and engineering reference value.

A highly efficient and reusable catalyst QA-HPMV was successfully prepared by the reaction of quinoline-2-formic acid (QA) with molybdovanadophosphoric heteropolyacid (H4PMo11VO40, HPMV) for the nitration of benzene. The physical and chemical properties of the sample was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis and thermogravimetric analysis (TG). The characterization results showed that the formed QA-HPMV retained the Keggin structure of HPMV. As a catalyst for benzene nitration, QA-HPMV showed good catalytic performance and the yield of nitrobenzene was 82.5% under the optimized reaction conditions. As a heterogeneous catalyst, QA-HPMV can be easily recycled from the reaction medium by filtering and remained highly catalytic performance even after five runs of recycling.

One bonded- and one discreted-Lindqvist hexatungstate-based copper hybrids (Cu-POMs) ([Cu2(O)OH(phen)2]2[W6O19]·6H2O (1) and [Cu2(phen)4Cl] [HW6O19]·2H2O (2) (phen = 1,10-phenanthroline)) were controllably synthesized and routinely characterized. Cu-POMs 1-2 consisted of identical [W6O19] unit and similar copper-phen complexes, the two units are bonded via four Cu-O chemical bonds in compound 1; however, compound 2 is discreted and stabilized by intermolecular electrostatic interactions. Importantly, these Cu-POMs catalysts were first applied in the novel reaction for the preparation of 2-phenylquinoxalines via the one-pot coupling and oxidation reactions of 2-haloanilines with vinyl azides or 3-phenyl-2H-azirines under mild conditions, and Cu-POMs 1 showed higher catalytic performance in good yields (79-84%). The reactions exhibit some functional group tolerance and allow for the preparation of a number of 2-phenylquinoxalines.