Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigati...Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.展开更多
Two new Mn(Ⅱ)coordination polymers,namely{[Mn_(2)(HL)(phen)_(3)(H_(2)O)_(2)]·7.5H_(2)O}_n(1)and[Mn_(4)(HL)_(2)(1,4-bib)_(3)(H_(2)O)_(2)]_n(2),were synthesized under hydrothermal conditions by using Mn(Ⅱ)ions an...Two new Mn(Ⅱ)coordination polymers,namely{[Mn_(2)(HL)(phen)_(3)(H_(2)O)_(2)]·7.5H_(2)O}_n(1)and[Mn_(4)(HL)_(2)(1,4-bib)_(3)(H_(2)O)_(2)]_n(2),were synthesized under hydrothermal conditions by using Mn(Ⅱ)ions and 6-(3',4'-dicarboxylphenoxy)-1,2,4-benzenetricarboxylic acid(H_(5)L)in the presence of N-auxiliary ligands 1,10-phenanthroline(phen)and1,4-bis(1H-imidazol-1-yl)benzene(1,4-bib).The structures of coordination polymers 1 and 2 were characterized by infrared spectroscopy,single-crystal X-ray diffraction,thermogravimetric analysis,and powder X-ray diffraction.Single-crystal X-ray diffraction reveals that 1 has a 1D chain structure based on binuclear Mn(Ⅱ)units,while 2 features a(3,8)-connected 3D network structure based on tetranuclear Mn(Ⅱ)units.Magnetic studies show that 1 and 2exhibit antiferromagnetic interactions between manganese ions.2 shows stronger antiferromagnetic interactions due to the shorter Mn…Mn distances within the tetranuclear manganese units.CCDC:2357601,1;2357602,2.展开更多
Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfull...Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2.展开更多
Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and m...Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.展开更多
The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge d...The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge distribution of the traditional M-N_(4)active site,the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is difficult to reach the optimal value,which seriously limits the catalytic efficiency.The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N_(4)site,which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure.In this paper,we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C:metal site regulation,coordination number engineering,non-metal atom doping,and carbon support regulation.Through an in-depth analysis of the structure-activity relationship between the coordination configuration and catalytic performance,the core challenges faced by current research are pointed out,and future research directions are envisioned.This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.展开更多
Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy.Nevertheless,one significant constraint on the perfo...Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy.Nevertheless,one significant constraint on the performance of fuel cells is the oxygen reduction reaction(ORR).It is meaningful to progress the development of representative ORR electrocatalysts.In recent times,there has been an intensified focus on single-atom catalysts(SACs)due to the advantages of homogeneous distribution and high atom utilization efficiency.In particular,the coordination structure of metal sites plays an important role in the electrochemical performance of SACs.However,the relationship between coordination structures and catalytic performance remains unclear.In this review,we summarized the research progress on SACs in electrocatalytic ORR in recent years.Then the structure-activity relationship in the symmetric and asymmetric coordination structures of SACs was clarified.We further proposed rational design principles for regulating the coordination structure of SACs.Finally,the opportunities and challenges were discussed.展开更多
The coordinated polymer [Ni（pda）（H2O）3]n 1 （pda = pyridine-2,3-dicarboxylate） with one-dimensional chain structure has been obtained by hydrothermal method. Its structure was determined by X-ray crystallography ...The coordinated polymer [Ni（pda）（H2O）3]n 1 （pda = pyridine-2,3-dicarboxylate） with one-dimensional chain structure has been obtained by hydrothermal method. Its structure was determined by X-ray crystallography with the following data： monoclinic, space group P21/c, a = 6.4153（4）, b = 21.6454（14）, c = 7.3783（5） A, β = 113.079（1）°, V = 942.56（11） A^3, Z = 4, C7H9NNiO7, Mr = 27.7.86, Dc = 1.958 g/cm^3,F（000） = 568 and μ（MoKa） = 2.081 mm^-1. The final R = 0.0194 and wR = 0.0515 for 1511 observed reflections with I 〉 2σ（I）. The title complex presents an infinite 1-D polymeric chain structure consisting of repeated basic units [Ni（pda）（H2O）3]n. The center Ni（Ⅱ） ions are coordinated by one nitrogen atom and three oxygen atoms from pda ligand as well as three H2O molecules in a slightly distorted octahedral environment. The intermolecular hydrogen bonds link the 1 D chains to form a 2D layered architecture.展开更多
Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four plan...Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.展开更多
Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by us...Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by using monthly horizontal wind field from NCEP/NCAR reanalysis data from 1948—2011. The following major conclusions are drawn: First, the double-layer structure of the HC is an objective fact, and it constantly exists in April,May, June, October and November in the Southern Hemisphere. Second, the double-layer structure is more obvious in the Southern than in the Northern Hemisphere. Since the double-layer structure is sloped in the vertical direction, it should be taken into consideration when analyzing the variations of the strength and location of the center of the HC.Third, the strength of the double-layer structure of the HC in the Southern Hemisphere consistently exhibits decadal variations with a strong, weak and strong pattern in all five months(April, May, June, October, and November), with cycles of 20-30 a and 40-60 a. Fourth, the center of the HC(mean position of the double-layer structure) in the Southern Hemisphere consistently and remarkably shifts southward in all the five months. The net poleward shifts over the 64 years are 5.18°, 2.11°, 2.50°, 1.79° and 5.76° for the five respective months, with a mean shift of 3.47°.展开更多
Four new five-coordinated anionic tin(Ⅳ) complexes with a form of [R_ n NH_ 4- n ][PhSn( μ 2-SCH_2COO)_2] were synthesized via the reaction of mercaptoacetic acid with phenyltin trichloride in the presence of dif...Four new five-coordinated anionic tin(Ⅳ) complexes with a form of [R_ n NH_ 4- n ][PhSn( μ 2-SCH_2COO)_2] were synthesized via the reaction of mercaptoacetic acid with phenyltin trichloride in the presence of different organic bases and characterized by means of IR, 1H NMR and MS spectroscopies. The crystal structure of [( i -Pr)_2NH_2] [PhSn( μ 2-SCH_2COO)_2] was determined by X-ray diffraction. In the crystal structure,the tin atom is five-coordinated and exists in trigonal bipyramid geometry with cell parameters a =1.1766(11) nm, b =1.3144(14) nm, c =1.3336(15) nm,β =90° and Z =4.展开更多
A coordination polymer \\-\%n\%(H\-2IDA=\%N\%\|iminodiacetic acid) was synthesized and characterized by single crystal X\|ray diffraction. The crystal belongs to the tetragonal system,the space group is \%P\|42\-1C\% ...A coordination polymer \\-\%n\%(H\-2IDA=\%N\%\|iminodiacetic acid) was synthesized and characterized by single crystal X\|ray diffraction. The crystal belongs to the tetragonal system,the space group is \%P\|42\-1C\% with the crystal cell parameters \%a\%=0\^81120(8) nm,\%b\%=0\^81120(8) nm,\%c\%=0\^96196(4) nm,\%V\%=0\^6330(1) nm\+3,\%M\%\-r=355\^17,\%R\%=0\^0224,\%wR\%=0\^061. The four carboxylic oxygen atoms of the different \%N\%\|iminodiacetic acid ligands and two water molecules coordinate to the manganese atom. The manganese atom is in an approximates octahedral coordination sphere. Each carboxylic acid ligand bridges two manganese atoms,forming two zig\|zag supramolecular chains. The twisted chains construct a two\|dimension layer structure with regularly arranged X\|shaped window cavity. The three\|dimension supramolecular network is formed by coordination bonds and hydrogen bonds.展开更多
A novel nitro-coordinated potassium compound [K(Htdc)(H_2O)]_n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an inf...A novel nitro-coordinated potassium compound [K(Htdc)(H_2O)]_n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an infinite K-O ladder-shaped chain, which is connected through carboxyl and unusual nitro-coordination of Htdc– anion. Then the 2D layers are further extended by intermolecular hydrogen-bonding to form a three-dimensional(3D) supramoleculalr network. Variable temperature powder X-ray diffractions, thermogravimetric analysis and nuclear magnetic resonance studies exhibit that the compound has a thermal-induced decarboxylative behavior.展开更多
A novel complex ZnTPPL1·3DMF 1（TPP = tetraphenylporphyrin,L1 = N-（4-（9-carbazolyl） phenyl）-N,N-di（4-pyridyl）amine） was prepared by a hydrothermal method and characterized by elemental analysis,IR,and sing...A novel complex ZnTPPL1·3DMF 1（TPP = tetraphenylporphyrin,L1 = N-（4-（9-carbazolyl） phenyl）-N,N-di（4-pyridyl）amine） was prepared by a hydrothermal method and characterized by elemental analysis,IR,and single-crystal X-ray diffraction analysis.Compound 1 crystallizes in triclinic,space group P1 with a = 13.3082（2）,b = 14.3276（2）,c = 18.6120（3） ,α = 109.853（1）,β = 95.054（1）,γ = 98.832（1）°,V = 3260.57（9） 3,Z = 2,Dc = 1.334 g/cm3,C81H69N11O3Zn,Mr = 1309.84,μ（MoKα） = 0.438 mm-1,F（000） = 1372,GOF = 1.159,the final R = 0.0482 and wR = 0.1479 for 12091 observed reflections（Ⅰ 〉 2σ（Ⅰ））.Crystal structure analyses revealed that L1 utilizes one pyridyl N atom to bind Zn via axial coordination,affording a 1：1 complex.The binding constant was estimated to be 1.74（7） × 10^4 M^-1 from electronic spectra measurements.展开更多
Lanthanum complex （phenH）2[La（NO3）5（phen）]·CH3OH （1, phen=phenanthroline） was synthesized and characterized by single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, s...Lanthanum complex （phenH）2[La（NO3）5（phen）]·CH3OH （1, phen=phenanthroline） was synthesized and characterized by single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/c with a=20.3040（3）, b=10.7091（1）, c=19.0771（2）, β=102.090（1）°, V=4056.07（8）3, Z=4, Dc=1.676 g/cm3, μ= 1.142 mm-1, F（000）=2056, the final R=0.0346 and wR=0.0793 for 9981 （Rint=0.0358） independent reflections. The mononuclear complex 1 consists of four parts： two phenH＋ cations formed by the protonation of phen, one complex anion [La（NO3）5（phen）]2-, and one solvent methanol molecule. The complex anion contains one phen and five nitrate ligands which both chelate the center La（III） ion, adopting a distorted twelve-coordinated icosahedral geometry. The cations, anion and solvent molecule are linked together by hydrogen bonds. One of the protonated phenanthrolines （phenH＋） acting as cation connects to the anion via N–H…O hydrogen bond directly, and the other one links to the anion through an intermediate solvent CH3OH via N–H…O and O–H…O hydrogen bonds. By the plentiful additional weak C–H…O intermolecular hydrogen bonds, the compound molecules construct a two-dimensional layer structure.展开更多
In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engin...In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.展开更多
A new copper（II） complex 3, Cu（C17H13F3O3）2·C5H5N, has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group C2/c with a = 17.8511（7）, b = 17.413...A new copper（II） complex 3, Cu（C17H13F3O3）2·C5H5N, has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group C2/c with a = 17.8511（7）, b = 17.4136（7）, c = 13.9425（7） A, β = 124.4830（10）°, V = 3572.5（3） A^3, Z = 4, C39H29CuF6NO6, Mr = 785.17,/7（000） = 1604, T = 292（2） K, Dc = 1.460 g/cm^3 and p = 0.691 mm^-1. The structure was refined to R = 0.0477 and wR = 0.1110 for 2935 observed reflections with I 〉 2σ（I）. For the title compound, X-ray analysis reveals that the copper（II） is penta-coordinated by four oxygen atoms from the corresponding 1-（4-（benzyloxy）phenyl）-4,4,4-trifluorobutane-1,3-dione ligands and one nitrogen atom of pyridine, forming a distorted square pyramidal geometry. It is found that the trifluoromethyl group, F（1）/F（1＇）, F（2）/F（2＇） and F（3）/F（3＇））, is disordered over two orientations in an approximate 3：1 ratio.展开更多
A metal-organic coordination polymer [Cd（tdc）（bimb）（μ2-H2O）]n （H2tdc = thiophe-ne-2,5-dicarboxylic acid, bimb = 1,4-bis（imidazol-l-yl）-butane） 1 has been hydrothermally synthe- sized and characterized by el...A metal-organic coordination polymer [Cd（tdc）（bimb）（μ2-H2O）]n （H2tdc = thiophe-ne-2,5-dicarboxylic acid, bimb = 1,4-bis（imidazol-l-yl）-butane） 1 has been hydrothermally synthe- sized and characterized by elemental analysis, IR, TG, luminescence spectrum and single-crystal X-ray diffraction. Colorless crystals crystallize in the triclinic system, space group P^-1 with a = 5.8945（3）, b = 10.3129（5）, c = 11.2226（5） A, a = 95.1430（10）,β = 97.9020（10）, γ = 90.5910（10）°, V = 672.84（6） A^3, C11H11CdN2O5S, Mr= 395.68, De = 1.953 g/cm^3, μ（MoKa） = 1.797 mm^-1, F（000） = 390, Z = 2, the final R = 0.0209 and wR = 0.0508 for 2514 observed reflections （I 〉 2σ（I））. The structure of 1 exhibits a two-dimensional layer-like structure.展开更多
A new coordination polymer, [Mn（L）（1,4-bdc）] （L = 11-fluoro-dipyrido[3,2- a：2＂,3 ＂- c]phenazine, 1,4-bdc - benzene-1,4-dicarboxylate）, has been synthesized through the hydrothermal method and characterized by...A new coordination polymer, [Mn（L）（1,4-bdc）] （L = 11-fluoro-dipyrido[3,2- a：2＂,3 ＂- c]phenazine, 1,4-bdc - benzene-1,4-dicarboxylate）, has been synthesized through the hydrothermal method and characterized by elemental analysis, IR and single-crystal X-ray diffraction. It crystallizes in triclinic, space group P1 with a = 9.7544（9）, b = 10.8254（10）, c = 11.5288（10） A, a = 114.1300（10）, β = 96.6110（10）, y = 105.0390（10）°, V= 1038.62（16）/k3, Z= 2, C26H13FMnN404, Mr = 519.34, Dc = 1.661 g/cm3, F（000） = 526, ,u（MoKa） = 0.691 mm^-, R = 0.0405 and wR = 0.0977. The 1,4-bdc dianions link the neighboring Mn（II） atoms to yield a two-dimensional layer structure. The L ligands are attached on both sides of the layer. The π-π interactions between the L ligands of neighboring layers result in a three-dimensional supramolecular architecture.展开更多
A new 2D coordination polymer, [Cd（tpim）（1,5-nds）]n （1）, was constructed from 1,5-naphthalenedi- sulfonate （1,5-nds）. 2.4,5-tri（4-pyridyl）-imidazole （tpim） and Cd（CH3COO）2.2H2O, which can be subsequently...A new 2D coordination polymer, [Cd（tpim）（1,5-nds）]n （1）, was constructed from 1,5-naphthalenedi- sulfonate （1,5-nds）. 2.4,5-tri（4-pyridyl）-imidazole （tpim） and Cd（CH3COO）2.2H2O, which can be subsequently used to promote the epoxide ring-opening reaction of epoxides and amines with remarkable catalytic activity. In addition, the thermal and luminescent properties of I in the solid state were also investigated.展开更多
A new Cd（Ⅱ） coordination polymer, namely, [Cd（1,3-bip）（3,5-pdc）]n （1,3-bip = 1,3-bis（imidazol）propane and 3,5-pdc = pyridine-3,5-dicarboxylic acid） has been synthesized under hydrothermal conditions. Compou...A new Cd（Ⅱ） coordination polymer, namely, [Cd（1,3-bip）（3,5-pdc）]n （1,3-bip = 1,3-bis（imidazol）propane and 3,5-pdc = pyridine-3,5-dicarboxylic acid） has been synthesized under hydrothermal conditions. Compound 1 was characterized by infrared spectrum, elemental analysis, powder X-ray diffraction （PXRD） and single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/c with a = 1.40178（7）, b = 1.72502（12）, c = 1.41635（6） ran, β = 92.653（4）°, V = 3.4212（3） nm3, Z = 4, C16HIsCdNsO4, Mr = 453.73, Dc = 1.762 g/cm3, F（000） = 1808,μ = 1.310 mm1, R = 0.0899 and wR = 0.1945. In compound 1, each 3,5-pdc ligand links three Cd（lI） ions and each Cd（Ⅱ） attaches to bip ligands to form a complicated 2D double-layer structure. In addition, the thermal stability and luminescent property of 1 have been studied in the solid state at room temperature.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074213 and 11574108)the National Key R&D Program of China(Grant No.2022YFA1403103)+2 种基金the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province(Grant No.ZR2023MA082)the Project of Introduction and Cultivation for Young Innovative Talents in Colleges and Universities of Shandong Province。
文摘Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.
文摘Two new Mn(Ⅱ)coordination polymers,namely{[Mn_(2)(HL)(phen)_(3)(H_(2)O)_(2)]·7.5H_(2)O}_n(1)and[Mn_(4)(HL)_(2)(1,4-bib)_(3)(H_(2)O)_(2)]_n(2),were synthesized under hydrothermal conditions by using Mn(Ⅱ)ions and 6-(3',4'-dicarboxylphenoxy)-1,2,4-benzenetricarboxylic acid(H_(5)L)in the presence of N-auxiliary ligands 1,10-phenanthroline(phen)and1,4-bis(1H-imidazol-1-yl)benzene(1,4-bib).The structures of coordination polymers 1 and 2 were characterized by infrared spectroscopy,single-crystal X-ray diffraction,thermogravimetric analysis,and powder X-ray diffraction.Single-crystal X-ray diffraction reveals that 1 has a 1D chain structure based on binuclear Mn(Ⅱ)units,while 2 features a(3,8)-connected 3D network structure based on tetranuclear Mn(Ⅱ)units.Magnetic studies show that 1 and 2exhibit antiferromagnetic interactions between manganese ions.2 shows stronger antiferromagnetic interactions due to the shorter Mn…Mn distances within the tetranuclear manganese units.CCDC:2357601,1;2357602,2.
文摘Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2.
基金Project supported by Guizhou Provincial Basic Research Program (Natural Science)(Qian Ke He Basic-ZK 2024 General 626)National Natural Science Foundation of China (52164018)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (13210025)。
文摘Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.
基金supported by the Natural Science Foundation of Hebei Province(no.E2024501010)the National Natural Science Foundation of China(no.52374301)+1 种基金the Shijiazhuang Basic Research Project(no.241790667A)the Performance Subsidy Fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(no.22567627H)。
文摘The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge distribution of the traditional M-N_(4)active site,the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is difficult to reach the optimal value,which seriously limits the catalytic efficiency.The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N_(4)site,which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure.In this paper,we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C:metal site regulation,coordination number engineering,non-metal atom doping,and carbon support regulation.Through an in-depth analysis of the structure-activity relationship between the coordination configuration and catalytic performance,the core challenges faced by current research are pointed out,and future research directions are envisioned.This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.
基金supported the National Natural Science Foundation of China(Nos.22108306 and 22478432)Taishan Scholars Program of Shandong Province(No.tsqn201909065)the Natural Science Foundation of Shandong Province(Nos.ZR2024JQ004 and ZR2021YQ15).
文摘Proton exchange membrane fuel cells have been identified as a potentially valuable technology for the efficient conversion of hydrogen energy into electrical energy.Nevertheless,one significant constraint on the performance of fuel cells is the oxygen reduction reaction(ORR).It is meaningful to progress the development of representative ORR electrocatalysts.In recent times,there has been an intensified focus on single-atom catalysts(SACs)due to the advantages of homogeneous distribution and high atom utilization efficiency.In particular,the coordination structure of metal sites plays an important role in the electrochemical performance of SACs.However,the relationship between coordination structures and catalytic performance remains unclear.In this review,we summarized the research progress on SACs in electrocatalytic ORR in recent years.Then the structure-activity relationship in the symmetric and asymmetric coordination structures of SACs was clarified.We further proposed rational design principles for regulating the coordination structure of SACs.Finally,the opportunities and challenges were discussed.
文摘The coordinated polymer [Ni（pda）（H2O）3]n 1 （pda = pyridine-2,3-dicarboxylate） with one-dimensional chain structure has been obtained by hydrothermal method. Its structure was determined by X-ray crystallography with the following data： monoclinic, space group P21/c, a = 6.4153（4）, b = 21.6454（14）, c = 7.3783（5） A, β = 113.079（1）°, V = 942.56（11） A^3, Z = 4, C7H9NNiO7, Mr = 27.7.86, Dc = 1.958 g/cm^3,F（000） = 568 and μ（MoKa） = 2.081 mm^-1. The final R = 0.0194 and wR = 0.0515 for 1511 observed reflections with I 〉 2σ（I）. The title complex presents an infinite 1-D polymeric chain structure consisting of repeated basic units [Ni（pda）（H2O）3]n. The center Ni（Ⅱ） ions are coordinated by one nitrogen atom and three oxygen atoms from pda ligand as well as three H2O molecules in a slightly distorted octahedral environment. The intermolecular hydrogen bonds link the 1 D chains to form a 2D layered architecture.
文摘Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.
基金National Natural Science Foundation of China(41475068,40805034)Special Scientific Research Project for Public Interest(GYHY201206009)Fundamental Research Funds for the Central Universities of China(lzujbky-2014-203)
文摘Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by using monthly horizontal wind field from NCEP/NCAR reanalysis data from 1948—2011. The following major conclusions are drawn: First, the double-layer structure of the HC is an objective fact, and it constantly exists in April,May, June, October and November in the Southern Hemisphere. Second, the double-layer structure is more obvious in the Southern than in the Northern Hemisphere. Since the double-layer structure is sloped in the vertical direction, it should be taken into consideration when analyzing the variations of the strength and location of the center of the HC.Third, the strength of the double-layer structure of the HC in the Southern Hemisphere consistently exhibits decadal variations with a strong, weak and strong pattern in all five months(April, May, June, October, and November), with cycles of 20-30 a and 40-60 a. Fourth, the center of the HC(mean position of the double-layer structure) in the Southern Hemisphere consistently and remarkably shifts southward in all the five months. The net poleward shifts over the 64 years are 5.18°, 2.11°, 2.50°, 1.79° and 5.76° for the five respective months, with a mean shift of 3.47°.
文摘Four new five-coordinated anionic tin(Ⅳ) complexes with a form of [R_ n NH_ 4- n ][PhSn( μ 2-SCH_2COO)_2] were synthesized via the reaction of mercaptoacetic acid with phenyltin trichloride in the presence of different organic bases and characterized by means of IR, 1H NMR and MS spectroscopies. The crystal structure of [( i -Pr)_2NH_2] [PhSn( μ 2-SCH_2COO)_2] was determined by X-ray diffraction. In the crystal structure,the tin atom is five-coordinated and exists in trigonal bipyramid geometry with cell parameters a =1.1766(11) nm, b =1.3144(14) nm, c =1.3336(15) nm,β =90° and Z =4.
文摘A coordination polymer \\-\%n\%(H\-2IDA=\%N\%\|iminodiacetic acid) was synthesized and characterized by single crystal X\|ray diffraction. The crystal belongs to the tetragonal system,the space group is \%P\|42\-1C\% with the crystal cell parameters \%a\%=0\^81120(8) nm,\%b\%=0\^81120(8) nm,\%c\%=0\^96196(4) nm,\%V\%=0\^6330(1) nm\+3,\%M\%\-r=355\^17,\%R\%=0\^0224,\%wR\%=0\^061. The four carboxylic oxygen atoms of the different \%N\%\|iminodiacetic acid ligands and two water molecules coordinate to the manganese atom. The manganese atom is in an approximates octahedral coordination sphere. Each carboxylic acid ligand bridges two manganese atoms,forming two zig\|zag supramolecular chains. The twisted chains construct a two\|dimension layer structure with regularly arranged X\|shaped window cavity. The three\|dimension supramolecular network is formed by coordination bonds and hydrogen bonds.
基金supported by the Natural Science Foundation of Henan Province(172102210410 and 172102310476)
文摘A novel nitro-coordinated potassium compound [K(Htdc)(H_2O)]_n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an infinite K-O ladder-shaped chain, which is connected through carboxyl and unusual nitro-coordination of Htdc– anion. Then the 2D layers are further extended by intermolecular hydrogen-bonding to form a three-dimensional(3D) supramoleculalr network. Variable temperature powder X-ray diffractions, thermogravimetric analysis and nuclear magnetic resonance studies exhibit that the compound has a thermal-induced decarboxylative behavior.
基金Supported by the Shanghai Pujiang Program (08PJ14037),NNSFC,SRF for ROCS,and SEM
文摘A novel complex ZnTPPL1·3DMF 1（TPP = tetraphenylporphyrin,L1 = N-（4-（9-carbazolyl） phenyl）-N,N-di（4-pyridyl）amine） was prepared by a hydrothermal method and characterized by elemental analysis,IR,and single-crystal X-ray diffraction analysis.Compound 1 crystallizes in triclinic,space group P1 with a = 13.3082（2）,b = 14.3276（2）,c = 18.6120（3） ,α = 109.853（1）,β = 95.054（1）,γ = 98.832（1）°,V = 3260.57（9） 3,Z = 2,Dc = 1.334 g/cm3,C81H69N11O3Zn,Mr = 1309.84,μ（MoKα） = 0.438 mm-1,F（000） = 1372,GOF = 1.159,the final R = 0.0482 and wR = 0.1479 for 12091 observed reflections（Ⅰ 〉 2σ（Ⅰ））.Crystal structure analyses revealed that L1 utilizes one pyridyl N atom to bind Zn via axial coordination,affording a 1：1 complex.The binding constant was estimated to be 1.74（7） × 10^4 M^-1 from electronic spectra measurements.
基金supported by the Scientific Research Common Program of Beijing Municipal Commission of Education (KM201010028008)
文摘Lanthanum complex （phenH）2[La（NO3）5（phen）]·CH3OH （1, phen=phenanthroline） was synthesized and characterized by single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/c with a=20.3040（3）, b=10.7091（1）, c=19.0771（2）, β=102.090（1）°, V=4056.07（8）3, Z=4, Dc=1.676 g/cm3, μ= 1.142 mm-1, F（000）=2056, the final R=0.0346 and wR=0.0793 for 9981 （Rint=0.0358） independent reflections. The mononuclear complex 1 consists of four parts： two phenH＋ cations formed by the protonation of phen, one complex anion [La（NO3）5（phen）]2-, and one solvent methanol molecule. The complex anion contains one phen and five nitrate ligands which both chelate the center La（III） ion, adopting a distorted twelve-coordinated icosahedral geometry. The cations, anion and solvent molecule are linked together by hydrogen bonds. One of the protonated phenanthrolines （phenH＋） acting as cation connects to the anion via N–H…O hydrogen bond directly, and the other one links to the anion through an intermediate solvent CH3OH via N–H…O and O–H…O hydrogen bonds. By the plentiful additional weak C–H…O intermolecular hydrogen bonds, the compound molecules construct a two-dimensional layer structure.
文摘In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.
基金supported by the Natural Science Foundation of the Educational Commission of Hubei Province (No. Q20082202)
文摘A new copper（II） complex 3, Cu（C17H13F3O3）2·C5H5N, has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group C2/c with a = 17.8511（7）, b = 17.4136（7）, c = 13.9425（7） A, β = 124.4830（10）°, V = 3572.5（3） A^3, Z = 4, C39H29CuF6NO6, Mr = 785.17,/7（000） = 1604, T = 292（2） K, Dc = 1.460 g/cm^3 and p = 0.691 mm^-1. The structure was refined to R = 0.0477 and wR = 0.1110 for 2935 observed reflections with I 〉 2σ（I）. For the title compound, X-ray analysis reveals that the copper（II） is penta-coordinated by four oxygen atoms from the corresponding 1-（4-（benzyloxy）phenyl）-4,4,4-trifluorobutane-1,3-dione ligands and one nitrogen atom of pyridine, forming a distorted square pyramidal geometry. It is found that the trifluoromethyl group, F（1）/F（1＇）, F（2）/F（2＇） and F（3）/F（3＇））, is disordered over two orientations in an approximate 3：1 ratio.
基金supported by the Science and Technology Research Projects of the Education Department of Jilin Province (No. 2012.479)
文摘A metal-organic coordination polymer [Cd（tdc）（bimb）（μ2-H2O）]n （H2tdc = thiophe-ne-2,5-dicarboxylic acid, bimb = 1,4-bis（imidazol-l-yl）-butane） 1 has been hydrothermally synthe- sized and characterized by elemental analysis, IR, TG, luminescence spectrum and single-crystal X-ray diffraction. Colorless crystals crystallize in the triclinic system, space group P^-1 with a = 5.8945（3）, b = 10.3129（5）, c = 11.2226（5） A, a = 95.1430（10）,β = 97.9020（10）, γ = 90.5910（10）°, V = 672.84（6） A^3, C11H11CdN2O5S, Mr= 395.68, De = 1.953 g/cm^3, μ（MoKa） = 1.797 mm^-1, F（000） = 390, Z = 2, the final R = 0.0209 and wR = 0.0508 for 2514 observed reflections （I 〉 2σ（I））. The structure of 1 exhibits a two-dimensional layer-like structure.
基金Supported by the Institute Foundation of Siping City (No.2009011)
文摘A new coordination polymer, [Mn（L）（1,4-bdc）] （L = 11-fluoro-dipyrido[3,2- a：2＂,3 ＂- c]phenazine, 1,4-bdc - benzene-1,4-dicarboxylate）, has been synthesized through the hydrothermal method and characterized by elemental analysis, IR and single-crystal X-ray diffraction. It crystallizes in triclinic, space group P1 with a = 9.7544（9）, b = 10.8254（10）, c = 11.5288（10） A, a = 114.1300（10）, β = 96.6110（10）, y = 105.0390（10）°, V= 1038.62（16）/k3, Z= 2, C26H13FMnN404, Mr = 519.34, Dc = 1.661 g/cm3, F（000） = 526, ,u（MoKa） = 0.691 mm^-, R = 0.0405 and wR = 0.0977. The 1,4-bdc dianions link the neighboring Mn（II） atoms to yield a two-dimensional layer structure. The L ligands are attached on both sides of the layer. The π-π interactions between the L ligands of neighboring layers result in a three-dimensional supramolecular architecture.
基金financial support from the National Natural Science Foundation of China(No.21272109)the Natural Science Foundation of Henan Province (No.112300410138)+1 种基金the Foundation of the Education Department of Henan Province(No.2011B150021)Luoyang Science and Technology Fund
文摘A new 2D coordination polymer, [Cd（tpim）（1,5-nds）]n （1）, was constructed from 1,5-naphthalenedi- sulfonate （1,5-nds）. 2.4,5-tri（4-pyridyl）-imidazole （tpim） and Cd（CH3COO）2.2H2O, which can be subsequently used to promote the epoxide ring-opening reaction of epoxides and amines with remarkable catalytic activity. In addition, the thermal and luminescent properties of I in the solid state were also investigated.
基金Supported by the National Natural Science Foundation of China(No.21373132)the Science Foundation of Education Department of Shaanxi Provincial Government(No.12JK0637)
文摘A new Cd（Ⅱ） coordination polymer, namely, [Cd（1,3-bip）（3,5-pdc）]n （1,3-bip = 1,3-bis（imidazol）propane and 3,5-pdc = pyridine-3,5-dicarboxylic acid） has been synthesized under hydrothermal conditions. Compound 1 was characterized by infrared spectrum, elemental analysis, powder X-ray diffraction （PXRD） and single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/c with a = 1.40178（7）, b = 1.72502（12）, c = 1.41635（6） ran, β = 92.653（4）°, V = 3.4212（3） nm3, Z = 4, C16HIsCdNsO4, Mr = 453.73, Dc = 1.762 g/cm3, F（000） = 1808,μ = 1.310 mm1, R = 0.0899 and wR = 0.1945. In compound 1, each 3,5-pdc ligand links three Cd（lI） ions and each Cd（Ⅱ） attaches to bip ligands to form a complicated 2D double-layer structure. In addition, the thermal stability and luminescent property of 1 have been studied in the solid state at room temperature.
