The research of cluster supply chains is a new direction and a hotspot of the industrial cluster theory. On the condition of the coordination game, the enterprises may be stuck on the non-efficient equilibrium status,...The research of cluster supply chains is a new direction and a hotspot of the industrial cluster theory. On the condition of the coordination game, the enterprises may be stuck on the non-efficient equilibrium status, which becomes an important problem that must be considered on cluster supply chains. A symmetrical coordination game model is constituted to describe the competition and cooperation relationship of the same-quality manufacturers on cluster supply chains. The methods of the non-cooperation game theory and the evolutionary game theory are respectively used to analyze the model, whose parameters＇ influences under each method are then compared. It can be concluded that the analysis of the evolutionary game theory is more realistic and practical. Finally, three approaches are considered to break away from being path-dependence locked-in non-efficient status during this coordination game evolutionary process, which provide the development of cluster supply chains with an effective forecasting and Pareto optimizing method.展开更多
The creation of a porous magnet is a long-sought academic goal since magnetism and porosity are hostile to one another. While long-range magnetic ordering needs spin carriers of short separation through short bridges,...The creation of a porous magnet is a long-sought academic goal since magnetism and porosity are hostile to one another. While long-range magnetic ordering needs spin carriers of short separation through short bridges, porosity relies on the use of extended connecting ligands. Here, we will give a survey of the cluster-based magnetic porous coordination polymers, i.e., 0-D MPCPs, according to their functional subunits： （1） nanoporous spin crossover materials with single metal nodes; （2） metal-radical approach with rigid organic radical ligands and single metal nodes; （C） PCPs with rigid organic ligands and metal oligomer nodes; （D） PCPs with metal complex linkers and polymetal cluster nodes; （E） PCPs with organo-polymetal cluster linkers and single metal nodes. The assembly from clusters can provide a reasonable route to resolve the hostility between magnetism and porosity. This assembly’s merits are obvious： the pore benefits from the big cluster according to ＂Scale Chemistry＂, and the functional framework inherits interesting physical properties from the clusters with a large ground spin S.展开更多
The coordination polymer, [Mn3（bpta）2（bip）2], （H3bpta = biphenyl-3,3＇,5-tricar- boxylic acid, bip = 2,6-bis（imidazole-1-yl）pyridine）, has been synthesized under hydrothermal con- ditions and characterized by ...The coordination polymer, [Mn3（bpta）2（bip）2], （H3bpta = biphenyl-3,3＇,5-tricar- boxylic acid, bip = 2,6-bis（imidazole-1-yl）pyridine）, has been synthesized under hydrothermal con- ditions and characterized by elemental analysis, FT-IR, XRD, TGA and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 14.919（3）, b = 9.780（2）, c = 20.352（7） A, V = 2344.4（10） A3, Z= 2, C52H32Mn3N10012, Mr = 1153.70, Dc = 1.634 g/cm3, p（MoKa） = 0.876 mm-1, F（000） = 1170, the finalR = 0.0605 and wR = 0.1177. The complex forms a 2D layer with trinuclear Mn（II） units and further assembles into a 3D supramolecular network structure through C-H..＇O hydrogen bonding and C-H...π interactions. Moreover, the negative J value indicates the presence of antiferromagnetic coupling between the Mn（II） ions within a trinuclear unit.展开更多
A novel Dy^（3＋） coordination compound,（H_2pipz）（H_3O）[Dy（pydc）_3]·11H_2O（1,pipz = piperazine and H_2pydc = pyridine-2,6-dicarboxylic acid）,has been hydrothermally synthesized and characterized by X-ray...A novel Dy^（3＋） coordination compound,（H_2pipz）（H_3O）[Dy（pydc）_3]·11H_2O（1,pipz = piperazine and H_2pydc = pyridine-2,6-dicarboxylic acid）,has been hydrothermally synthesized and characterized by X-ray single-crystal diffraction,elemental analysis. It is interesting that the packing structure of compound 1 contains 22-core water clusters. Compound 1 is extended into a threedimensional supramolecular structure via O···H···O hydrogen bonding interactions. Furthermore,the luminescent property of compound 1 was also investigated.展开更多
The coordination polymer,[Mn3（L） 2（adip） 3]·2H2O（L = 2-（4-fluorophenyl） -1H-imidazo[4,5-f] [1,10]phenanthroline and H2adip = adipic acid） ,has been synthesized under hydro-thermal conditions and character...The coordination polymer,[Mn3（L） 2（adip） 3]·2H2O（L = 2-（4-fluorophenyl） -1H-imidazo[4,5-f] [1,10]phenanthroline and H2adip = adipic acid） ,has been synthesized under hydro-thermal conditions and characterized by elemental analysis,IR and single-crystal X-ray diffraction. It crystallizes in triclinic,space group P1^- with a = 8.4085（11） ,b = 11.1273（14） ,c = 14.5758（18） ,α = 78.528（2） ,β = 75.425（2） ,γ = 78.143（2） °,V = 1276.0（3） A^3,Z = 1,C56H50F2Mn3N8O14,Mr = 1261.86,Dc = 1.642 g/cm^3,F（000） = 647,μ（MoKa） = 0.819 mm^-1,R = 0.0446 and wR = 0.1008. The backbones of the two types of adip dianions link the neighboring trinuclear Mn（Ⅱ） clusters to yield a two-dimensional layer structure. The large conjugated L ligands are located on both sides of the two-dimensional layers. Additionally,the O-H···O,O-H···N and N-H···O hydrogen bonds further stabilize the structure.展开更多
In wireless sensor networks(WSNs) with single sink,the nodes close to the sink consume their energy too fast due to transferring a large number of data packages,resulting in the "energy hole" problem.Deployi...In wireless sensor networks(WSNs) with single sink,the nodes close to the sink consume their energy too fast due to transferring a large number of data packages,resulting in the "energy hole" problem.Deploying multiple sink nodes in WSNs is an effective strategy to solve this problem.A multi-sink deployment strategy based on improved particle swarm clustering optimization(IPSCO) algorithm for WSNs is proposed in this paper.The IPSCO algorithm is a combination of the improved particle swarm optimization(PSO) algorithm and K-means clustering algorithm.According to the sink nodes number K,the IPSCO algorithm divides the sensor nodes in the whole network area into K clusters based on the distance between them,making the total within-class scatter to minimum,and outputs the center of each cluster.Then,multiple sink nodes in the center of each cluster can be deployed,to achieve the effects of partition network reasonably and deploy multi-sink nodes optimally.The simulation results show that the deployment strategy can prolong the network lifetime.展开更多
The Coordinate Descent Method for K-means(CDKM)is an improved algorithm of K-means.It identifies better locally optimal solutions than the original K-means algorithm.That is,it achieves solutions that yield smaller ob...The Coordinate Descent Method for K-means(CDKM)is an improved algorithm of K-means.It identifies better locally optimal solutions than the original K-means algorithm.That is,it achieves solutions that yield smaller objective function values than the K-means algorithm.However,CDKM is sensitive to initialization,which makes the K-means objective function values not small enough.Since selecting suitable initial centers is not always possible,this paper proposes a novel algorithm by modifying the process of CDKM.The proposed algorithm first obtains the partition matrix by CDKM and then optimizes the partition matrix by designing the split-merge criterion to reduce the objective function value further.The split-merge criterion can minimize the objective function value as much as possible while ensuring that the number of clusters remains unchanged.The algorithm avoids the distance calculation in the traditional K-means algorithm because all the operations are completed only using the partition matrix.Experiments on ten UCI datasets show that the solution accuracy of the proposed algorithm,measured by the E value,is improved by 11.29%compared with CDKM and retains its efficiency advantage for the high dimensional datasets.The proposed algorithm can find a better locally optimal solution in comparison to other tested K-means improved algorithms in less run time.展开更多
A new compound,[Cu（mal）（tmdpy）（H2O）]·4H2O（1,H2mal = malonic acid,tmdpy = 4,4＇-trimethylenedipyridine） has been synthesized by the hydrothermal synthesis and structurally characterized by X-ray crystallog...A new compound,[Cu（mal）（tmdpy）（H2O）]·4H2O（1,H2mal = malonic acid,tmdpy = 4,4＇-trimethylenedipyridine） has been synthesized by the hydrothermal synthesis and structurally characterized by X-ray crystallography. It crystallizes in triclinic,space group P1^- with a = 9.1662（6）,b = 10.6266（7）,c = 11.3056（7）A,α = 84.6390（10）,β = 72.1030（10）,γ = 73.0420（10） o,V = 1002.37（11）A^3,C16H26CuN2O9,Mr = 453.93,Z = 2,Dc = 1.504 g/cm^3,μ = 1.140 mm^-1,F（000） = 474,R = 0.0375 and wR = 0.0975 for 3187 observed reflections（I 〉 2σ（I）） . In the structure of 1,the tmdpy ligands link the [Cu（mal）（H2O） ] units into an infinite chain,and the water molecules and carboxylate oxygen donors（O（2） and O（4）） from the mal ligands cooperatively built an interesting hydrogen bonding network with unprecedented pseudo water tape substructures.展开更多
The title Mn（Ⅱ） coordination polymer,poly{[heptaaqua-（μ4-bi-phenyl-3,3？,5,5？-tetracarboxylate）-bimanganese（Ⅱ）] pentahydrate},[Mn_2（bpta）（H_2O）_7]_n·5n H_2O（I）,is crystallized from a mixture of bi...The title Mn（Ⅱ） coordination polymer,poly{[heptaaqua-（μ4-bi-phenyl-3,3？,5,5？-tetracarboxylate）-bimanganese（Ⅱ）] pentahydrate},[Mn_2（bpta）（H_2O）_7]_n·5n H_2O（I）,is crystallized from a mixture of biphenyl-3,3？,5,5？-tetracarboxylic acid（H_4bpta） and MnCl_2·4H_2O in waterethanol under room temperature. Its asymmetric unit consists of one and two halves of crystallographically independent Mn（Ⅱ） cations,one fully deprotonated H4 bpta ligand,seven coordinated water molecules and five solvent water as vip molecules. In I,each Mn（Ⅱ） atom is octahedrally coordinated by six oxygen atoms from bpta^（4-） anions and coordinated water molecules. In the Mn（Ⅱ） cations,one half Mn（Ⅱ） ion of them located at a 2-fold axis generating a trinuclear [Mn_3（H_2O）_2（RCOO）_2] linker by μ1,1-O（water） and μ1,3-O,O？（carboxylate） bridges and another half Mn（Ⅱ） ion with an inversion is a mononuclear linker. These neighbouring trinuclear and mononuclear Mn（Ⅱ） cations are linked together by biphenyl-3,3？,5,5？-tetracarboxylates to form a three-dimensional framework with a（42.84） topology of a（4,4）-connected net,in which the positions of the trinuclear [Mn_3（H_2O）_2（R-COO）_2] linker as a 4-connector linking four bpta^（4-） ligands in I reproduce an eagle-shaped arrangement. The polymeric structure exhibits a water channel with an accessible void of 797.1 ？~3,amounting to 15.7% of the total unit-cell volume. Each of the cavities in the network is occupied by solvent water molecules.展开更多
Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low price.In this work,a series o...Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low price.In this work,a series of well-dispersed nitrogen-coordinated Ru-clusters on carbon black(Ru_(x)N_(y)/C)were prepared by pyrolyzing different Ru-containing sandwich compounds as the Ru sources.The higher thermal stability of these complexed sandwich precursors(bis(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)monomer,dichloro(p-cymene)Ru(II)dimer,and chloro(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)tetramer)affords the control of coordinated state for the resulting Ru-clusters,in comparison of that derived from ruthenium chlorides.After the pyrolysis treatment,the Ru coordinated state in Ru_(x)N_(y)/C,with the Ru–N and Ru–Ru bonds,still showed the structural inheritance from the Ru(II)monomer,dimer,and tetramer,but using ruthenium chlorides as the Ru source resulted in the nanoscale Ru agglomerations.The ORR testing exhibited that the Ru_(x)N_(y)/C sample derived from the Ru(II)tetramer(Ru_(x)N_(y)/C-T)presents the higher catalytic activity than the other obtained samples in either alkaline or acidic electrolytes.Even in the acidic electrolyte,Ru_(x)N_(y)/C-T shows the comparable ORR activity to that of Pt/C catalysts,and it shows the superior tolerance against methanol and CO.The X-ray absorption spectroscopy and density functional theory calculations demonstrate that these tetra-nuclear Ru-clusters could be the most active site due to their broadened d-orbital bands and lower energy d-band center than those of other subnano species and nanocrystals,and their favorable Yeager-type adsorption of O_(2)-molecules is also contributed to promoting O–O bond cleavage and accelerating the ORR process.展开更多
OBJECTIVE To explore a novel pH-sensitive fluorescent probe for in vivo tumor imaging.METHODS Zn5 were obtained in 140℃ after mixed with Me OH,water,Zn(NO_3)2·6 H_2O,H4L and trimethylamine.The fluorescence spect...OBJECTIVE To explore a novel pH-sensitive fluorescent probe for in vivo tumor imaging.METHODS Zn5 were obtained in 140℃ after mixed with Me OH,water,Zn(NO_3)2·6 H_2O,H4L and trimethylamine.The fluorescence spectra of Zn5 with the same concentration in different pH aqueous solutions were detected.And the stability of Zn5 was investigated by time dependent fluorescence emission spectra of Zn5 in BSA aqueous solution and 5.0% serum solution.Then,the cytotoxicity of Zn5 was detected by MTT assays.To clarify whether a similar fluorescence response occurs in biological organisms,He La cells were pretreated with probe Zn5(0.5 μmol·L^(-1)) and fluorescence imaging were collected for targeting lysosomes in living cells because of lysosomes′ acidic microenvironment.The A375 tumor-bearing mice were used to assess the imaging ability of Zn5 in vivo.Mouse tumor xenografts were established by injection of A375 cells with 2×10~6 cells per flank.Probe(1 μg·g^(-1)) was administered to mice by injection.Images were obtained using IVIS Spectrum CT Imaging System.RESULTS There is a 11-fold intensity increasing as the pH values changing from 8 to 2.The almost unchanged emission intensities suggest Zn5 is stable in both BSA and serum.Zn5 has negligible cytotoxicity for He La,293 T and CHO-K1 cells.Zn5 can selectively display lysosomes in living cells.Both the 2D and 3D images in vivo distinguish the tumor from other tissues with good fluorescence contrast.CONCLUSION The high chemical stability,emission in the Vis/NIR range,pH sensitivity,a pKa located in the tumor pH range,and low toxicity make Zn5 is suitable for application as a pH-sensitive fluorescent probe for bio-imaging.展开更多
基金the National Natural Science Foundation of China (60374023)the Natural ScienceFoundation of Guangdong Province (011629).
文摘The research of cluster supply chains is a new direction and a hotspot of the industrial cluster theory. On the condition of the coordination game, the enterprises may be stuck on the non-efficient equilibrium status, which becomes an important problem that must be considered on cluster supply chains. A symmetrical coordination game model is constituted to describe the competition and cooperation relationship of the same-quality manufacturers on cluster supply chains. The methods of the non-cooperation game theory and the evolutionary game theory are respectively used to analyze the model, whose parameters＇ influences under each method are then compared. It can be concluded that the analysis of the evolutionary game theory is more realistic and practical. Finally, three approaches are considered to break away from being path-dependence locked-in non-efficient status during this coordination game evolutionary process, which provide the development of cluster supply chains with an effective forecasting and Pareto optimizing method.
基金supported by the State Key Laboratory of Structural Chemistry, NNSFC (20733003)Chinese Academy of Sciences (KJCX2-YW-M05)+1 种基金973 Program (2007CB815301, 2006CB932900)the NSF of Fujian Province (2006L2005, 2006J0014)
文摘The creation of a porous magnet is a long-sought academic goal since magnetism and porosity are hostile to one another. While long-range magnetic ordering needs spin carriers of short separation through short bridges, porosity relies on the use of extended connecting ligands. Here, we will give a survey of the cluster-based magnetic porous coordination polymers, i.e., 0-D MPCPs, according to their functional subunits： （1） nanoporous spin crossover materials with single metal nodes; （2） metal-radical approach with rigid organic radical ligands and single metal nodes; （C） PCPs with rigid organic ligands and metal oligomer nodes; （D） PCPs with metal complex linkers and polymetal cluster nodes; （E） PCPs with organo-polymetal cluster linkers and single metal nodes. The assembly from clusters can provide a reasonable route to resolve the hostility between magnetism and porosity. This assembly’s merits are obvious： the pore benefits from the big cluster according to ＂Scale Chemistry＂, and the functional framework inherits interesting physical properties from the clusters with a large ground spin S.
基金conducted in the framework of a project sponsored by the National Natural Science Foundation of China(No.21071100)Liaoning Baiqianwan Talents Program and the LNET(LJQ2011038)
文摘The coordination polymer, [Mn3（bpta）2（bip）2], （H3bpta = biphenyl-3,3＇,5-tricar- boxylic acid, bip = 2,6-bis（imidazole-1-yl）pyridine）, has been synthesized under hydrothermal con- ditions and characterized by elemental analysis, FT-IR, XRD, TGA and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 14.919（3）, b = 9.780（2）, c = 20.352（7） A, V = 2344.4（10） A3, Z= 2, C52H32Mn3N10012, Mr = 1153.70, Dc = 1.634 g/cm3, p（MoKa） = 0.876 mm-1, F（000） = 1170, the finalR = 0.0605 and wR = 0.1177. The complex forms a 2D layer with trinuclear Mn（II） units and further assembles into a 3D supramolecular network structure through C-H..＇O hydrogen bonding and C-H...π interactions. Moreover, the negative J value indicates the presence of antiferromagnetic coupling between the Mn（II） ions within a trinuclear unit.
基金financially supported by the Foundation of Fujian Educational Committee(JA14348)
文摘A novel Dy^（3＋） coordination compound,（H_2pipz）（H_3O）[Dy（pydc）_3]·11H_2O（1,pipz = piperazine and H_2pydc = pyridine-2,6-dicarboxylic acid）,has been hydrothermally synthesized and characterized by X-ray single-crystal diffraction,elemental analysis. It is interesting that the packing structure of compound 1 contains 22-core water clusters. Compound 1 is extended into a threedimensional supramolecular structure via O···H···O hydrogen bonding interactions. Furthermore,the luminescent property of compound 1 was also investigated.
基金Supported by the Institute Foundation of Siping City (No.2009011)
文摘The coordination polymer,[Mn3（L） 2（adip） 3]·2H2O（L = 2-（4-fluorophenyl） -1H-imidazo[4,5-f] [1,10]phenanthroline and H2adip = adipic acid） ,has been synthesized under hydro-thermal conditions and characterized by elemental analysis,IR and single-crystal X-ray diffraction. It crystallizes in triclinic,space group P1^- with a = 8.4085（11） ,b = 11.1273（14） ,c = 14.5758（18） ,α = 78.528（2） ,β = 75.425（2） ,γ = 78.143（2） °,V = 1276.0（3） A^3,Z = 1,C56H50F2Mn3N8O14,Mr = 1261.86,Dc = 1.642 g/cm^3,F（000） = 647,μ（MoKa） = 0.819 mm^-1,R = 0.0446 and wR = 0.1008. The backbones of the two types of adip dianions link the neighboring trinuclear Mn（Ⅱ） clusters to yield a two-dimensional layer structure. The large conjugated L ligands are located on both sides of the two-dimensional layers. Additionally,the O-H···O,O-H···N and N-H···O hydrogen bonds further stabilize the structure.
基金the Key Project of the National Natural Science Foundation of China(No.61134009)National Natural Science Foundations of China(Nos.61473077,61473078)+4 种基金Program for Changjiang Scholars from the Ministry of Education,ChinaSpecialized Research Fund for Shanghai Leading Talents,ChinaProject of the Shanghai Committee of Science and Technology,China(No.13JC1407500)Innovation Program of Shanghai Municipal Education Commission,China(No.14ZZ067)the Fundamental Research Funds for the Central Universities,China(No.15D110423)
文摘In wireless sensor networks(WSNs) with single sink,the nodes close to the sink consume their energy too fast due to transferring a large number of data packages,resulting in the "energy hole" problem.Deploying multiple sink nodes in WSNs is an effective strategy to solve this problem.A multi-sink deployment strategy based on improved particle swarm clustering optimization(IPSCO) algorithm for WSNs is proposed in this paper.The IPSCO algorithm is a combination of the improved particle swarm optimization(PSO) algorithm and K-means clustering algorithm.According to the sink nodes number K,the IPSCO algorithm divides the sensor nodes in the whole network area into K clusters based on the distance between them,making the total within-class scatter to minimum,and outputs the center of each cluster.Then,multiple sink nodes in the center of each cluster can be deployed,to achieve the effects of partition network reasonably and deploy multi-sink nodes optimally.The simulation results show that the deployment strategy can prolong the network lifetime.
基金funded by National Defense Basic Research Program,grant number JCKY2019411B001funded by National Key Research and Development Program,grant number 2022YFC3601305funded by Key R&D Projects of Jilin Provincial Science and Technology Department,grant number 20210203218SF.
文摘The Coordinate Descent Method for K-means(CDKM)is an improved algorithm of K-means.It identifies better locally optimal solutions than the original K-means algorithm.That is,it achieves solutions that yield smaller objective function values than the K-means algorithm.However,CDKM is sensitive to initialization,which makes the K-means objective function values not small enough.Since selecting suitable initial centers is not always possible,this paper proposes a novel algorithm by modifying the process of CDKM.The proposed algorithm first obtains the partition matrix by CDKM and then optimizes the partition matrix by designing the split-merge criterion to reduce the objective function value further.The split-merge criterion can minimize the objective function value as much as possible while ensuring that the number of clusters remains unchanged.The algorithm avoids the distance calculation in the traditional K-means algorithm because all the operations are completed only using the partition matrix.Experiments on ten UCI datasets show that the solution accuracy of the proposed algorithm,measured by the E value,is improved by 11.29%compared with CDKM and retains its efficiency advantage for the high dimensional datasets.The proposed algorithm can find a better locally optimal solution in comparison to other tested K-means improved algorithms in less run time.
基金supported by the Natural Science Foundation of Fujian Province (No.2010J01029)
文摘A new compound,[Cu（mal）（tmdpy）（H2O）]·4H2O（1,H2mal = malonic acid,tmdpy = 4,4＇-trimethylenedipyridine） has been synthesized by the hydrothermal synthesis and structurally characterized by X-ray crystallography. It crystallizes in triclinic,space group P1^- with a = 9.1662（6）,b = 10.6266（7）,c = 11.3056（7）A,α = 84.6390（10）,β = 72.1030（10）,γ = 73.0420（10） o,V = 1002.37（11）A^3,C16H26CuN2O9,Mr = 453.93,Z = 2,Dc = 1.504 g/cm^3,μ = 1.140 mm^-1,F（000） = 474,R = 0.0375 and wR = 0.0975 for 3187 observed reflections（I 〉 2σ（I）） . In the structure of 1,the tmdpy ligands link the [Cu（mal）（H2O） ] units into an infinite chain,and the water molecules and carboxylate oxygen donors（O（2） and O（4）） from the mal ligands cooperatively built an interesting hydrogen bonding network with unprecedented pseudo water tape substructures.
基金supported by the National Natural Science Foundation of China(No.21571118)
文摘The title Mn（Ⅱ） coordination polymer,poly{[heptaaqua-（μ4-bi-phenyl-3,3？,5,5？-tetracarboxylate）-bimanganese（Ⅱ）] pentahydrate},[Mn_2（bpta）（H_2O）_7]_n·5n H_2O（I）,is crystallized from a mixture of biphenyl-3,3？,5,5？-tetracarboxylic acid（H_4bpta） and MnCl_2·4H_2O in waterethanol under room temperature. Its asymmetric unit consists of one and two halves of crystallographically independent Mn（Ⅱ） cations,one fully deprotonated H4 bpta ligand,seven coordinated water molecules and five solvent water as vip molecules. In I,each Mn（Ⅱ） atom is octahedrally coordinated by six oxygen atoms from bpta^（4-） anions and coordinated water molecules. In the Mn（Ⅱ） cations,one half Mn（Ⅱ） ion of them located at a 2-fold axis generating a trinuclear [Mn_3（H_2O）_2（RCOO）_2] linker by μ1,1-O（water） and μ1,3-O,O？（carboxylate） bridges and another half Mn（Ⅱ） ion with an inversion is a mononuclear linker. These neighbouring trinuclear and mononuclear Mn（Ⅱ） cations are linked together by biphenyl-3,3？,5,5？-tetracarboxylates to form a three-dimensional framework with a（42.84） topology of a（4,4）-connected net,in which the positions of the trinuclear [Mn_3（H_2O）_2（R-COO）_2] linker as a 4-connector linking four bpta^（4-） ligands in I reproduce an eagle-shaped arrangement. The polymeric structure exhibits a water channel with an accessible void of 797.1 ？~3,amounting to 15.7% of the total unit-cell volume. Each of the cavities in the network is occupied by solvent water molecules.
基金supported by the National Key Research and Development Program of China(No.2022YFE0110400)the National Natural Science Foundation of China(Nos.52122207,52173245,52130206,U20A20337,and 52221006)the Fundamental Research Funds for the Central Universities(No.CLYY2022).
文摘Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low price.In this work,a series of well-dispersed nitrogen-coordinated Ru-clusters on carbon black(Ru_(x)N_(y)/C)were prepared by pyrolyzing different Ru-containing sandwich compounds as the Ru sources.The higher thermal stability of these complexed sandwich precursors(bis(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)monomer,dichloro(p-cymene)Ru(II)dimer,and chloro(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)tetramer)affords the control of coordinated state for the resulting Ru-clusters,in comparison of that derived from ruthenium chlorides.After the pyrolysis treatment,the Ru coordinated state in Ru_(x)N_(y)/C,with the Ru–N and Ru–Ru bonds,still showed the structural inheritance from the Ru(II)monomer,dimer,and tetramer,but using ruthenium chlorides as the Ru source resulted in the nanoscale Ru agglomerations.The ORR testing exhibited that the Ru_(x)N_(y)/C sample derived from the Ru(II)tetramer(Ru_(x)N_(y)/C-T)presents the higher catalytic activity than the other obtained samples in either alkaline or acidic electrolytes.Even in the acidic electrolyte,Ru_(x)N_(y)/C-T shows the comparable ORR activity to that of Pt/C catalysts,and it shows the superior tolerance against methanol and CO.The X-ray absorption spectroscopy and density functional theory calculations demonstrate that these tetra-nuclear Ru-clusters could be the most active site due to their broadened d-orbital bands and lower energy d-band center than those of other subnano species and nanocrystals,and their favorable Yeager-type adsorption of O_(2)-molecules is also contributed to promoting O–O bond cleavage and accelerating the ORR process.
基金supported by Distinguished Young Scholars(21525101)the NSFC(91422302,and 21371037)
文摘OBJECTIVE To explore a novel pH-sensitive fluorescent probe for in vivo tumor imaging.METHODS Zn5 were obtained in 140℃ after mixed with Me OH,water,Zn(NO_3)2·6 H_2O,H4L and trimethylamine.The fluorescence spectra of Zn5 with the same concentration in different pH aqueous solutions were detected.And the stability of Zn5 was investigated by time dependent fluorescence emission spectra of Zn5 in BSA aqueous solution and 5.0% serum solution.Then,the cytotoxicity of Zn5 was detected by MTT assays.To clarify whether a similar fluorescence response occurs in biological organisms,He La cells were pretreated with probe Zn5(0.5 μmol·L^(-1)) and fluorescence imaging were collected for targeting lysosomes in living cells because of lysosomes′ acidic microenvironment.The A375 tumor-bearing mice were used to assess the imaging ability of Zn5 in vivo.Mouse tumor xenografts were established by injection of A375 cells with 2×10~6 cells per flank.Probe(1 μg·g^(-1)) was administered to mice by injection.Images were obtained using IVIS Spectrum CT Imaging System.RESULTS There is a 11-fold intensity increasing as the pH values changing from 8 to 2.The almost unchanged emission intensities suggest Zn5 is stable in both BSA and serum.Zn5 has negligible cytotoxicity for He La,293 T and CHO-K1 cells.Zn5 can selectively display lysosomes in living cells.Both the 2D and 3D images in vivo distinguish the tumor from other tissues with good fluorescence contrast.CONCLUSION The high chemical stability,emission in the Vis/NIR range,pH sensitivity,a pKa located in the tumor pH range,and low toxicity make Zn5 is suitable for application as a pH-sensitive fluorescent probe for bio-imaging.
