Yanfeng Tang

Yolk–shell ZnWO4 microspheres: one-pot synthesis, characterization and photocatalytic properties

Novel yolk–shell ZnWO4 microspheres have been fabricated via a one-pot hydrothermal process in the presence of L-aspartic acid (L-Asp). The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption experimentation and UV-vis absorption spectroscopy. The effects of the reaction conditions on the morphology and crystallinity of the products were studied, as well as the amount of L-Asp, reaction time and reaction temperature. As the chelating agent and shape modifier, L-Asp plays a key role in the crystal growth of the yolk–shell ZnWO4 microspheres. A possible formation mechanism for the yolk–shell microspheres is proposed. The photocatalytic properties of the yolk–shell ZnWO4 microspheres were investigated by the decomposition of Rhodamine B (RhB) and methylene blue (MB) under UV light irradiation and the results show that they have excellent photocatalytic activities. Furthermore, the obtained yolk–shell ZnWO4 microspheres are chemically stable and the efficiency remained almost the same after being recycled five times, suggesting that the yolk–shell ZnWO4 microspheres are promising photocatalysts for practical applications.

A new Co-nitroimidazolate–dicarboxylate pillared-layer network with various types of channels and ultra-large cages for gas uptake

A novel porous coordination polymer based on a Co-nitroimidazolate–dicarboxylate pillared-layer network, namely, [Co7(bdc)6(nIm)2(H2O)6]·3H2O·3DMF, (1, H2bdc = 1,4-benzenedicarboxylic acid, nIm = 2-nitroimidazole), has been synthesized by a solvothermal reaction. The microporous layers of 1 consisted of two kinds of SBUs, six-connected Co3(O2CR)6 and three-connected [Co2(O2CR)3]+, forming unprecedented Co3-Co2-bdc-based layers with three types of diamonded grids in the bc plane. The layers are further linked by bidentate-bridging nIm ligands as pillars into a 3-D metal–organic framework with two kinds of rectangular channels parallel to the c axis. It is worth mentioning that compound 1 also exhibits uniquely polyhedral cages with a maximum diagonal dimension of up to 31.019 A, which has fallen in the scope of mesoporous (2–50 nm). To systematically evaluate the channels and special cages, the adsorption ability of 1 was measured by N2, H2 and CO2 sorption experiments. Topological analysis indicates that compound 1 adopts a new topological structure with a point symbol of {412·614·82}{46}2. Moreover, thermal gravimetric analysis (TGA) of as-synthesized 1 reveals a stability range up to 311 °C.

Synthesis, structure and characterization of Fe6 molecular clusters with peripheral sulfur atom-capped silver nanoparticles

There are rare reports of high-nuclear transition metal clusters with thiol groups in their periphery. In this work, a novel cluster, [Fe6O2(OH)2(O2CC6H4SCH3)10(hep)2]·CH3CN·CH2Cl2 (Fe6) has been constructed by coordinating an octahedral Fe(III) ion with 4-mercaptobenzoate and hepH (hepH = 2-(2-hydroxyethyl) pyridine). The functionalized thiomethyl groups around the periphery of the Fe6 cluster may provide binding sites for the surfaces of some specific materials, such as noble metals. Therefore, silver nanoparticle coated Fe6 (Ag@Fe6) complexes have been prepared by spontaneous self-assembly reactions. Transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) images show that the Fe6 cluster layer is formed on the surface of the silver nanoparticles and the diameter of the Fe6 cluster is about 2 nm. In addition, powder X-ray diffraction (XRD), UV-vis spectroscopy, surface enhanced Raman spectroscopy (SERS), and cyclic voltammetry of the Fe6 and Ag@Fe6 complexes were also investigated.

Synthesis, structures, and luminescence of two 2-D microporous metal-organic frameworks in the zinc (cadmium)-dicarboxylate-imidazolate system

Abstract Two 2-D microporous metal–organic frameworks, [Zn(BDC)(MbIm)]·2DMF (1) and [Cd3(BDC)3(MbIm)2(DMF)2]·2DMF (2), have been synthesized by solvothermal reaction of 1,4-benzenecarboxylic acid (H2BDC) and 2-methylbenzimidazole (MbIm) with zinc/cadmium nitrate. Single-crystal X-ray diffraction analysis indicates that 1 consists of the well-known zinc paddle-wheel motif which is linked by bridging dicarboxylates to form 2-D square grids. The 2-D layers stack offset due to the effect of the spatial structure of MbIm ligand and hydrogen-bonding interaction between MbIm and guest molecules. Similarly, 2 is constructed by six-connected Cd3(μ-O2CR)6(MbIm)2 units and bridging carboxylates, resulting in a 2-D layer structure with triangular grids. Topology analysis reveals that 1 exhibits a 2-D tetragonal plane network with {44·62} topology symbol, while 2 possesses a six-connected {36·46·53} topological network. Analysis of the luminescence spectra demonstrates that the complexes have good luminescent intensities with greater red-shift (82 nm for 1 and 69 nm for 2) corresponding to free MbIm. Elemental analyses, infrared spectra, powder X-ray diffraction, and thermogravimetric analyses of 1 and 2 have been investigated.

Nanoplate-assembled hierarchical cake-like ZnO microstructures: solvothermal synthesis, characterization and photocatalytic properties

Employing NH4BF4 as a fluoride source, novel hierarchical cake-like ZnO microstructures have been fabricated by a simple, template-free, environmentally-friendly DMF (N,N-dimethylformamide)-mediated solvothermal route. The products were characterized by XRD, SEM, TEM and nitrogen adsorption–desorption and PL. The SEM and TEM results indicated that the hierarchical cake-like ZnO were assembled from numerous tiny nanoplates. DMF acted as solvent and structure-directing agent to guide the formation of ZnO nuclei and the self-assembled preferential growth from smaller building units (nanoplates) to larger cake-like ZnO microstructures. The as-prepared samples, ZnO or ZnOHF could be regulated by altering the two major reaction parameters (the amount of DMF and fluoride source). Time-dependent morphological evolution results revealed that self-assembly and Ostwald ripening were the main formation mechanism for the hierarchical ZnO microstructure. Furthermore, the photocatalytic activity of the as-prepared ZnO samples was evaluated by the degradation of Rhodamine B (RhB) under UV light irradiation. Such hierarchical cake-like ZnO microstructures showed an excellent photocatalytic activity. Additionally, the cake-like ZnO microstructures were chemically stable, and the efficiency remained almost the same after being recycled five times.

A novel glycopolymeric ultraviolet absorber covering UV-A and UV-B ranges

In this communication, a novel biocompatible polymeric ultraviolet absorber (UVA), poly(HAB-co-OAG-co-AMC) (PHOA), covering UV-A and UV-B ranges was designed and prepared. The photo-antioxidant tests indicate that there is a synergism between UV-A and UV-B monomers. The cytotoxic experiments demonstrate that PHOA has good biocompatibility.

Penta­carbonyl-1κ2C,2κ3C-(ferrocenyl­diphenyl­phosphine-1κP)[μ-2-(4-methyl­phen­yl)-2-aza­propane-1,3-dithiol­ato-1:2κ4S,S′:S,S′]diiron(I)(Fe—Fe)

The title compound, [Fe2(C9H11NS2){Fe(C5H5)(C17H14P)}(CO)5], was prepared as an azadithiolato–iron model for the iron-only hydrogenase active site. The Fe2S2 unit exhibits a butterfly conformation and the ferrocenyldiphenylphosphine ligand is trans to the Fe—Fe bond. The Fe—Fe distance of 2.5160 (8) Å is longer than found in related model structures. Intramolecular C—H⋯S and intermolecular C—H⋯O hydrogen bonds are observed.

Controlled synthesis of CeVO4 hierarchical hollow microspheres with tunable hollowness and their efficient photocatalytic activity

Well-dispersed hollow CeVO4 microspheres with tunable hollowness and porosity have been synthesized via a simple hydrothermal method using L-aspartic acid (L-Asp) as the capping agent. The products were characterized by XRD, SEM, TEM and DRS. The XRD results showed that the as-prepared samples were tetragonal phase CeVO4 with high crystallinity. SEM and TEM observations indicated that the hierarchical hollow microspheres with different hollowness were constructed from nanoparticles, cubes or nanoflakes. N2 adsorption–desorption measurements revealed that the BET specific surface area of the typical CeVO4 hollow microspheres was up to 106.54 m2 g−1. During the synthesis, the amount of L-Asp and the reaction time were found to play important roles in determining the growth process and final morphologies of the CeVO4 products. Time-dependent experiments clearly revealed that the CeVO4 hierarchical hollow microspheres were governed by the self-assembly and Ostwald ripening process. Rhodamine B (RhB) was used as the dye pollutant for evaluating the photocatalytic properties of the products under UV radiation. The CeVO4 hierarchical hollow microspheres exhibited excellent photocatalytic activity and good stability even after five repeated cycles of use, indicating that the CeVO4 hierarchical hollow microspheres can be good candidates for photocatalytic degradation of organic pollutants.

Rational design and synthesis of an amino-functionalized hydrogen-bonded network with an ACO zeolite-like topology for gas storage

Based upon the typically hydrogen-bonded network, metal–organic cubes, the amino functional group was first introduced onto the surface of the cube to raise the polarizability of the framework by in situ hydrolysis of the precursor 2-amino-4,5-dicyanoimidazole (ADCIm) with octahedral In3+ ions under solvothermal conditions, resulting in a supramolecular network with very high CO2 (135.8 cm3 g−1 at 273 K/1 atm) and H2 (2.03 wt% at 77 K/1 atm) adsorption capacities and an exceptional thermostability range up to 416 °C.

Synthesis and characterization of a novel polymeric ultraviolet absorber and its properties

A novel polymeric ultraviolet absorber (UVA) poly (HAB-co-AMC-co-AA) (PHHA) has been prepared by solution copolymerization from 2-hydroxy-4-acryloy benzophenone (HAB), p-acryloy-methyl cinnamate (AMC) and acrylic acid and analyzed using FT-IR, UV–Vis, 1H NMR and GPC. The results revealed two PHHA absorption peaks in UV-A and UV-B. Polymerizable monomer HAB was synthesized by the reaction of 2,4-dihydroxybenzophenone (UV-0) and acryloyl chloride (AC). Another monomer, AMC, was prepared from p-hydroxy-methyl cinnamate and AC. The results showed that HAB and AMC have high UV-absorbing performance in UV-A and UV-B, respectively. The photoantioxidant ability tests indicated that PHHA is an effective polymeric UVA that covers UV-A and UV-B ranges, and a synergism between the two monomers was observed.