排序方式: 共有64条查询结果,搜索用时 15 毫秒
31.
Two compounds, namely, [Cu(bbi)](2)[Cu(2)(bbi)(2)(delta-Mo(8)O(26))0.5][alpha-Mo(8)O(26)]0.5 (1) and [Cu(bbi)][Cu(bbi)(theta-Mo(8)O(26))0.5] (2), where bbi is 1,1'-(1,4-butanediyl)bis(imidazole), were synthesized under hydrothermal conditions at different pH values. Their crystal structures were determined by X-ray diffraction. Compounds 1 and 2 are supramolecular isomers with a polythreaded topology based on octamolybdate building blocks. 相似文献
32.
Considering the atmospheric extinction and turbulence effects,we investigate the propagation performances of supercontinuum laser sources in atmospheric turbulence statistically by using the numerical simulation method,and the differences in propagation properties between the super-continuum(SC)laser and its pump laser are also analyzed.It is found that the propagation characteristics of super-continuum laser are almost similar to those of the pump laser.The degradation of source coherence degree may cause the relative beam spreading and scintillation indexes to decrease at different propagation distances or different turbulence strengths.The root-mean-square value of beam wandering is insensitive to the variation of source correlation length,and less aperture averaging occurs when the laser source becomes less coherent.Additionally,from the point of view of beam wandering,the SC laser has no advantage over the pump laser.Although the pump laser can bring about a bigger aperture average,the SC laser has a lower scintillation which may be due to the multiple wavelength homogenization effects on intensity fluctuations.This would be the most important virtue of the SC laser that can be utilized to improve the performance of laser engineering. 相似文献
33.
Long-Zhang Dong Lei Zhang Dr. Jiang Liu Qing Huang Meng Lu Dr. Wen-Xin Ji Prof. Ya-Qian Lan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2681-2685
A series of stable heterometallic Fe2M cluster-based MOFs ( NNU-31-M , M=Co, Ni, Zn) photocatalysts are presented. They can achieve the overall conversion of CO2 and H2O into HCOOH and O2 without the assistance of additional sacrificial agent and photosensitizer. The heterometallic cluster units and photosensitive ligands excited by visible light generate separated electrons and holes. Then, low-valent metal M accepts electrons to reduce CO2, and high-valent Fe uses holes to oxidize H2O. This is the first MOF photocatalyst system to finish artificial photosynthetic full reaction. It is noted that NNU-31-Zn exhibits the highest HCOOH yield of 26.3 μmol g−1 h−1 (selectivity of ca. 100 %). Furthermore, the DFT calculations based on crystal structures demonstrate the photocatalytic reaction mechanism. This work proposes a new strategy for how to design crystalline photocatalyst to realize artificial photosynthetic overall reaction. 相似文献
34.
Mi Zhang Meng Lu Dr. Zhong-Ling Lang Dr. Jiang Liu Ming Liu Jia-Nan Chang Le-Yan Li Lin-Jie Shang Min Wang Prof. Shun-Li Li Prof. Ya-Qian Lan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6562-6568
A strategy to covalently connect crystalline covalent organic frameworks (COFs) with semiconductors to create stable organic–inorganic Z-scheme heterojunctions for artificial photosynthesis is presented. A series of COF–semiconductor Z-scheme photocatalysts combining water-oxidation semiconductors (TiO2, Bi2WO6, and α-Fe2O3) with CO2 reduction COFs (COF-316/318) was synthesized and exhibited high photocatalytic CO2-to-CO conversion efficiencies (up to 69.67 μmol g−1 h−1), with H2O as the electron donor in the gas–solid CO2 reduction, without additional photosensitizers and sacrificial agents. This is the first report of covalently bonded COF/inorganic-semiconductor systems utilizing the Z-scheme applied for artificial photosynthesis. Experiments and calculations confirmed efficient semiconductor-to-COF electron transfer by covalent coupling, resulting in electron accumulation in the cyano/pyridine moieties of the COF for CO2 reduction and holes in the semiconductor for H2O oxidation, thus mimicking natural photosynthesis. 相似文献
35.
36.
Yu-Xia Kong You-Ying Di Ya-Qian Zhang Wei-Wei Yang Zhi-Cheng Tan 《Thermochimica Acta》2009,495(1-2):33-37
Crystal structure of 1-dodecylamine hydrochloride (C12H28NCl)(s) has been determined by an X-ray crystallography. Lattice potential energy and the molar volumes of the solid compound and its cation were respectively obtained. The enthalpy of dissolution of the compound was measured by an isoperibol solution-reaction calorimeter at 298.15 K. The molar enthalpy of dissolution at infinite dilution was determined to be , and relative apparent molar enthalpies (ΦL), relative partial molar enthalpies (L2) of the compound and relative partial molar enthalpies (L1) of the solvent (double distilled water) at different concentrations m (mol kg−1) were obtained through fitted multiple regression equation by means of Pitzer's theory. Finally, hydration enthalpies of the substance and its cation were calculated by designing a thermochemical cycle in accordance with lattice potential energy and the molar enthalpy of dissolution at infinite dilution . 相似文献
37.
Yong-Ming Lu Ya-Qian Lan Yan-Hong Xu Zhong-Min Su Shun-Li Li Hong-Ying Zang Guang-Juan Xu 《Journal of solid state chemistry》2009,182(11):3105-3112
To investigate the relationship between topological types and molecular building blocks (MBBs), we have designed and synthesized a series of three-dimensional (3D) interpenetrating metal-organic frameworks based on different polygons or polyhedra under hydrothermal conditions, namely [Cd(bpib)0.5(L1)] (1), [Cd(bpib)0.5(L2)]·H2O (2), [Cd(bpib)0.5(L3)] (3) and [Cd(bib)0.5(L1)] (4), where bpib=1,4-bis(2-(pyridin-2-yl)-1H-imidazol-1-yl)butane, bib=1,4-bis(1H-imidazol-1-yl)butane, H2L1=4-(4-carboxybenzyloxy)benzoic acid, H2L2=4,4′-(ethane-1,2-diylbis(oxy))dibenzoic acid and H2L3=4,4′-(1,4-phenylenebis(methylene))bis(oxy)dibenzoic acid, respectively. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Compounds 1–3 display α-Po topological nets with different degrees of interpenetration based on the similar octahedral [Cd2(–COO)4] building blocks. Compound 4 is a six-fold interpenetrating diamondoid net based on tetrahedral MBBs. By careful inspection of these structures, we find that various carboxylic ligands and N-donor ligands with different coordination modes and conformations, and metal centers with different geometries are important for the formation of the different MBBs. It is believed that different topological types lie on different MBBs with various polygons or polyhedra. Such as four- and six-connected topologies are formed by tetrahedral and octahedral building blocks. In addition, with the increase of carboxylic ligands’ length, the degrees of interpenetration have been changed in the α-Po topological nets. And the luminescent properties of these compounds have been investigated in detail. 相似文献
38.
In this paper, we investigate a modified differential-difference KP equation which is shown to have a continuum limit into the mKP equation. It is also shown that the solution of the modified differential-difference KP equation is related to the solution of the differential-difference KP equation through a Miura transformation. We first present the Grammian solution to the modified differential-difference KP equation, and then produce a coupled modified differential-difference KP system by applying the source generation procedure. The explicit N-soliton solution of the resulting coupled modified differential-difference system is expressed in compact forms by using the Grammian determinant and Casorati determinant. We also construct and solve another form of the self-consistent sources extension of the modified differential-difference KP equation, which constitutes a Bäcklund transformation for the differential-difference KP equation with self-consistent sources. 相似文献
39.
Synthesis and crystal structure of polymer cobalt(II) complex, 1,2,4,5-benzenetetracarboxylate hexaimidazole tetraaqua cobalt (II) tetrahydrate 总被引:1,自引:0,他引:1
The crystal structure of the title complex {[Co(TCB)2/2-(IMI)2(H2O)2][Co(IMI)4(H2O)2] } (H2O)4 (where TCB = 1,2,4,5-benzenetetracarboxylic anion; IMI = imidazole) has been determined by X-ray diffraction method. Crystal data for {[Co(TCB)2/2(IMI)2(H2O)2][Co(IMI)4(H2O)2]}-(H2O)4: triclinic, space group P 1, a = 1.0647(2) nm, b = 1.1165(1)nm,c = 1.00361(1)nm,α = 91.56(1)°,β = 111.34(1)°, γ = 115.642(10)°, V = 0.9772(3) nm5, Z = 1. The polymer cobalt (II) complex has a novel three-dimension network structure. Co(1) atom and Co(2) atom both are coordinated in an octahedral arrangement and located in the center of the coordination anion and the center of the coordination cation, respectively. Moreover four carboxyl groups of TCB are divided into two types, two para-carboxyl groups bridge Co(1) atom in monodentate fashion and other two para-carboxyl groups are in free. 相似文献
40.
Hao XR Wang XL Qin C Su ZM Wang EB Lan YQ Shao KZ 《Chemical communications (Cambridge, England)》2007,(44):4620-4622
A 3D chiral nanoporous coordination framework consisting of homochiral nanotubes assembled from octuple helices with a 19.4 A by 22.4 A aperture is formed by the parallel alignment of eight infinite helical chains. 相似文献