Highly sensitive WO3 hollow-sphere gas sensors

In this paper, we describe how WO(3) hollow spheres have been synthesized in solution phase by the controlled hydrolysis of WCl(6) using novel carbon microspheres as the templates. All of the products were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), and transmission electron microscopy (TEM). The as-synthesized spheres had large diameters of about 400 nm and thin shells of about 30 nm composed of numerous small nanocrystals. Prompted by the porous structure and small crystal size of the shell wall, we constructed WO(3) hollow-sphere gas sensors and found that these sensors had good sensitivity to alcohol, acetone, CS(2), and other organic gases.     

Asymmetric syntheses of protected (2S,3S,4S)-3-hydroxy-4-methylproline and 4′-tert-butoxyamido-2′-deoxythymidine

Described herein is a versatile approach to (i) (2S,3S,4S)-3-hydroxy-4-methylproline 3, a constituent of echinocandins and related oligopeptide antibiotics; (ii) (2S,3S)-3-hydroxyproline 1; (iii) (2R,3S)-3-hydroxyprolinol 5, and (iv) 4′-tert-butoxyamido-2′-deoxythymidine 6b. The method features a stepwise regio- and diastereoselective reductive furylation of the protected (3S,4S)-4-methylmalimide 10, (S)-malimide 9, and a chemoselective oxidative transformation of the furyl group to the carboxyl group as the key steps.     

Syntheses and Crystal Structures of Complexes [Cu（C14H8S3O4Br）] （C4H9NO） and[Ni（C14H9N2O3Br）]（C4H9NO）

The title compounds, Cu（L1）（C4H8NHO） and Ni（L2）（C4H8NHO） （H2L1 = 5-bromosalicylaldehyde-p-nitrobenzoylhydrazone, H2L2 = 5-bromosalicylaldehyde-p-hydroxybenzoylhydrazone）, have been obtained and characterized by single-crystal X-ray diffraction. Complex 1 belongs to the triclinic system, space group P1 with a = 8.6960（2）, b = 9.957（2）, c = 11.878（2）A, α = 73.36（3）, β = 78.25（3）, γ = 82.64（3）°, V = 962.1（3） A^3, Mr= 512.81, Z = 2, F（000） = 514, Dc = 1.770 g/cm^3,μ（MoKα） = 3.251, R = 0.0337 and wR = 0.0846. Complex 2 is of monoclinic, space group P21/c with a = 13.313（2）, b = 8.2096（1）, c = 21.890（3） A,β = 125.737（3）°, V = 1941.9（4） A^3, Mr= 478.97, Z = 4, F（000） = 968, Dc = 1.638 g/cm^3,μ（MoKα） = 3.085, R = 0.0356 and wR = 0.0817. The ligands form a satisfactory N2O2 square plane around the metal centers in two compounds. Different patterns of hydrogen bonds are observed owing to the presence of different substituents on aromatic ring of the acylhydrazone Schiff bases. In complex 1, square-planar copper（Ⅱ） complexes are linked by intermolecular hydrogen bonds leading to zigzag infinite chains. In complex 2, the metal complexes are linked via hydrogen bonds to form corrugated sheets in a staggered fashion; 3D channels along the b axis are constructed through other non-covalent interactions between the neighboring layers.     

溶剂对柔性配体1,3,5-三(三氮唑-1-甲基)-2,4,6-三甲苯的银配合物的影响

通过在不同溶剂中硝酸银与1,3,5-三（1,2,4-三氮唑-1-甲基）-2,4,6-三甲苯（ttmb）的反应,合成了2种新型的银配合物：{[Ag（ttmb）（H₂O）]NO₃}_n（1）、{[Ag（ttmb）]NO₃·H₂O）}_n（2）。研究了室温条件下,2个配合物与相关ttmb配体的固态荧光性质。通过元素分析、粉末和单晶X射线衍射分析、红外光谱分析等对其结构进行表征,结果表明化合物1包含一个高度起伏的二维网状结构,化合物2具有一个二维的（6,3）网状结构。     

A New Approach to the Asymmetric Synthesis of 3-Methylpyrrolidine Alkaloids

3-Methylpyrrolidine alkaloids 1-5,isolated from the poison gland of several species of ants Leptothoracini (Myrmicinae), have been found to be pheromones and chemical weapons of them^[1,2].Since these alkaloids are only available at nanogram scale, the development of asymmetric synthesis is of importance, in particular for evaluating their bioactivities.     

Syntheses, Structures, and Some Properties of Three Vanadium Selenites

Three novel vanadium selenites with the formulae [（VO2）（1,10-phenanthtoline）（SeO3H）]2 1, [（VO2）（2,2′-bipyridine）]2（SeO3） 2 and [（VO）（H2O）（SeO3）2]2（HaEDD） 3 （EDD = N1,N1′-（ethane-1,2-diyl）diethane-1,2-diamine） were hydrothermally synthesized, and characterized with elemental analysis, FT-IR spectrum, Raman spectrum, TG-DTA analysis, EPR spectra, and single-crystal X-ray diffraction analysis. Compound I belongs to the triclinic system, space group P1^- with a = 7.7527（5）, b = 9.5345（10）, c = 9.8192（8） A^°, α = 92.712（3）, β = 105.540（3）, γ = 108.154（4）°, V = 657.66（1） A^°^3, Mr = 782.22, Z = 1, F（000） = 384,μ（MoKa） = 3.544 mm^-1, R = 0.0432 and wR = 0.1142; Compound 2 is of orthorhombic system, space group F212121 with a = 7.6574（15）, b = 14.916（3）, c = 19.085（4） A, V = 2179.8（8） Aa, Mr = 605.21, Z = 4, F（000） = 1200, μ（MoKa） = 2.579 mm^-1, R = 0.0338 and wR = 0.0658; Compound 3 belongs to the triclinic system, space group P1^- with a = 9.247（2）, b = 9.659（2）, c = 7.2651（19） A^°, α = 98.171（7）, β = 103.709（5）, γ = 114.712（13）°, V = 550.9（2） A^°^3, Mr = 828.03, Z = 1, F（000） = 400, μ（MoKa） = 7.537 mm^-1, R = 0.0641 and wR = 0.2118. Compound 1 is constructed from alternating corner-shared [VO4N2] octahedra and SeO3H units, forming a dimeric vanadium unit. These assemblies are further linked into an infinite chain via hydrogen bonds along the a axis. In the structure of 2, two distinct V centers form centrosymmetric [V2O6N4] clusters through edge-sharing, and the SeO3 unit serves as a capping unit to fix the oxovanadate cluster. In the structure of 3, each [VO6] octahedron shares four oxygen atoms with adjacent Se atoms, while every SeO3 unit shares two oxygen atoms with neighboring V atoms. This connectivity of alternating VO6 and SeO3 units results in a joint-like chain. Based on the TGA analysis, these three compounds are thermally stable under 200℃ .     

Synthesis of indoles through Rh(III)-catalyzed C–H cross-coupling with allyl carbonates

A practical Rh-catalyzed reaction was developed to achieve 2-alkyl-substituted indole synthesis. The reaction can tolerate a variety of synthetically important functional groups. The indole products can also be transformed into other important skeletons. Two bioactive compounds, that is indomethacin and pravadoline were prepared using the new method.     

Dissipation of Nonlinear Wave in Inhomogeneous Dust Plasma Crystal

A Korteweg-de Vires-type （KdV-type） equation and a modified Nonlinear Schrodinger equation （NLSE） for the dust lattice wave （DLW） are derived in a weakly inhomogeneous dust plasma crystal. It seems that the amplitude and the velocity of the dust lattice solitary waves decay exponentiaJly with increasing time in a dust lattice. The modulational instability of this dust lattice envelope waves is investigated as well. It is found that the waves are modulational stable under certain conditions. On the other hand, the waves are modulationaJ unstable if the conditions are not satisfied.     

Reference Section Method for Mixed State Geometric Phase in Nonunitary Evolution

We propose the reference section method to obtain a geometric phase for the mixed states in nonunitary evolution. The reference connection on density operator space is defined. That the parallel transport method and reference section method are essentially two aspects of in phase concept is pointed out.     

Flexible Gradient Poly(ether-ester) from the Copolymerization of Epoxides and ε-Caprolactone Mediated by a Hetero-bimetallic Complex

Copolymerization is a commonly employed method for optimizing the properties of polymer materials. Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether, and to develop more high-performance, multi-purpose polymer materials. Herein, the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-Al complex in the presence of PPNCl for the copolymerization of epoxides and ε-caprolactone(CL). Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL, affording copolymers with a gradient sequence structure. The dynamic thermomechanical analysis(DMA) study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio. This study provides a theoretical basis for the preparation of high-performance polymer materials.