Herein,the electronic structures and electronic circular dichroism(ECD)spectra of the chiral Wells-Dawson(W-D)polyoxoanion[(L,D-C_(6)H_(10)N_(3)O_(2))P_(2)Mo_(18)O_(62)]^(5-)(1a/1b)and chiral polyoxoanion[(L,D-C_(6)H_...Herein,the electronic structures and electronic circular dichroism(ECD)spectra of the chiral Wells-Dawson(W-D)polyoxoanion[(L,D-C_(6)H_(10)N_(3)O_(2))P_(2)Mo_(18)O_(62)]^(5-)(1a/1b)and chiral polyoxoanion[(L,D-C_(6)H_(10)N_(3)O_(2))PMo_(9)O_(31)(OH_(2))_(3)]^(2-)(2a/2b)are investigated using density functional theory(DFT)and time-dependent DFT(TDDFT)calculations.Compared to the fully oxidized[P_(2)Mo_(18)O_(62)]^(6-)structure,the Mo-Ob bond lengths in the one-electron reduced state,[P_(2)Mo_(18)O_(62)]^(7-),tends to be average.It is reasonable that organic ligands can transfer electrons to POMs and affect their chirality.The energy difference between the chiral L-[P_(2)Mo_(18)O_(62)]^(6-)with D_(3)symmetry and ideal[P_(2)Mo_(18)O_(62)]^(6-)with D_(3h)symmetry is 5.88 kcal mol^(-1),which suggests that chirality inversion may occur from the L-isomer to the D-isomer through the ideal[P_(2)Mo_(18)O_(62)]^(6-)by crossing a small energy barrier.Meanwhile,the interaction energy between the L-isomer and L-histidine ligand is larger than that of L-isomer and D-histidine,which indicates that L,D-[P_(2)Mo_(18)O_(62)]^(6-)is induced and further separated by the chiral histidine.The origins of the chiral polyoxoanion are mainly ascribed to charge-transfer(CT)transitions from the O atoms to Mo atoms or organic ligands to Mo atoms.These results confirm that organic cations have an induced effect on chiral POMs.展开更多
The redox and acidic properties of α-Keggin anions[PW_(11)O_(39)ME]^(4−)(M=Nb,Ta;E=O,S,Se)have been investigated by using the density functional theory(DFT)method.The calculated results for the studied clusters are c...The redox and acidic properties of α-Keggin anions[PW_(11)O_(39)ME]^(4−)(M=Nb,Ta;E=O,S,Se)have been investigated by using the density functional theory(DFT)method.The calculated results for the studied clusters are consistent with the hypothesis that the substitution of one O atom by S or Se atoms in polyoxometalates(POMs)modifies the relative energy of the lowest unoccupied molecular orbital,inducing slight changes in the redox properties of POMs.The electronic structures and reduction energies of[PW_(11)O_(39)ME]^(4−)(M=Nb,Ta;E=O,S,Se)confirm that the substitution of one O atom by S and Se atoms in POMs enhances the redox properties,which is in good agreement with the cyclic voltammetry characterization of α-[PW+(11)NbO_(40)]^(4−) and α-[PW_(11)NbSO_(39)]^(4−).The bonding energies for adding the first proton to the anions and for ammonia coordination to the protonated α-[PW_(11)O_(39)NbE]^(4−)(E=O,S,Se)were simulated to study the basicity of external oxygen sites and the acidity.The results show that the protonation energy becomes more positive after substitution by S and Se,indicating that the substitution enhances the acidity of POMs.The adsorption energy of ammonia in the case of α-[PW_(11)O_(39)NbE]^(4−)(E=S,Se)is more negative than that of α-[PW_(11)O_(40)NbO]^(4−),which also provides the same result as mentioned above.展开更多
Two new compounds with microporous Co3[MnMo9O32].15H2O(1) and Cu3[MnMo9O32].15H2O(2) have been synthesized,and characterized by IR,element analysis,TG and single-crystal X-ray analysis.The structure analyses reveal th...Two new compounds with microporous Co3[MnMo9O32].15H2O(1) and Cu3[MnMo9O32].15H2O(2) have been synthesized,and characterized by IR,element analysis,TG and single-crystal X-ray analysis.The structure analyses reveal that compounds 1 and 2 are isostructural.In crystal,the Waugh-type polyoxoanions [MnMo9O32]6-are connected by Co2+ or Cu2+ cations to a 3D open-framework,which possesses channels along the [1 2 2] direction of approximately 8.27 × 11.97 .The photocatalytic performances of compounds 1 and 2 for photodegradation of RhB with UV irradiation have been studied,which show a good photocatalytic activity for photodegradation of RhB.展开更多
A novel compound(NH4)2Y(H2O)8[PMo10V2O40]·10H2O has been prepared in an aqueous solution and characterized by elemental analysis,IR,and TG-DTG analysis.X-ray diffraction analysis was carried out on(NH4)2Y(H2O)8[P...A novel compound(NH4)2Y(H2O)8[PMo10V2O40]·10H2O has been prepared in an aqueous solution and characterized by elemental analysis,IR,and TG-DTG analysis.X-ray diffraction analysis was carried out on(NH4)2Y(H2O)8[PMo10V2O40]·10H2O single crystal,which crystallizes in the monoclinic system of a space group P21/C with a=0.9871(3)nm,b=1.5424(5)nm,c=2.7924(9)nm,β=94.183(5)°and Z=2.In the compound,a two-dimensional network is constructed by the PMo10V2O405-anion and the Y(H2O)83+cation building blocks via hydrogen bonding exhibiting the porous structure.展开更多
By employing electrostatic interaction as driving force, an organic/inorganic composite with positively charged dimethyl dialkyl-chain ammonium surfactants encapsulating negatively charged (NH 4) 12[Mo 36(NO) ...By employing electrostatic interaction as driving force, an organic/inorganic composite with positively charged dimethyl dialkyl-chain ammonium surfactants encapsulating negatively charged (NH 4) 12[Mo 36(NO) 4O 108(H 2O) 16]·33H 2O polyoxoanion was prepared. The structure of the novel organic/inorganic hybrid particle with hydrophilic core and hydrophobic shell in a defined stoichiometric ratio was confirmed by element analysis, 1H NMR and FT-IR spectra. The property of the polyoxoanion was changed due to the encapsulation and it can be dissolved in organic solvent such as chloroform, benzene and toluene, but not dissolved in water.展开更多
A simple and effective method for constructing highly efficient oxygen reduction catalysts with trace amount of isolated cobalt was firstly developed by the pyrolysis of Co-centered polyoxometalate@metalorganic framew...A simple and effective method for constructing highly efficient oxygen reduction catalysts with trace amount of isolated cobalt was firstly developed by the pyrolysis of Co-centered polyoxometalate@metalorganic framework (Co-POM@MOF).The Co-centered polyoxometalate ([Co W_(12)O_(40)]^(6-)) was confined in the well-defined void space of ZIF-8 to achieve homogeneous dispersion of polyoxoanions,where the isolated Co centers were well surrounded by the W-O shell and ZIF-8 framework.The Co-POM@MOF-derived N-doping porous carbon (Co-W-NC) with trace cobalt content was facilely prepared by the pyrolysis of the Co-POM@MOF under Ar atmosphere.The single dispersion of polyoxoanions in the metal-organic framework with complete separation of Co center surrounding by W-O shell and ZIF-8 framework ensures the uniform dispersion of Co atoms,confirmed by the Fourier transform extended X-ray absorption fine structure measurement.The Co-W-NC composite catalysts exhibit high performance for oxygen reduction reactions with a half-wave potential of 0.835 V in 0.1 mol/L KOH solution with excellent durability,which is much superior to that of the control samples derived from the[PW_(12)O_(40)]@ZIF-8,and the commercial Pt/C.This work highlights a new insight for constructing highly efficient catalysts via the introduction of metal-centered polyoxometalate into metal-organic framework following the high temperature treatment process.展开更多
A hydrothermal reaction of zinc acetate with molybdenum trioxide, vanadium pentoxide, phosphorus pentoxide and 2,2?-bpy (2,2?-bipyridine) led to the title compound [Zn(2,2?- bpy)2(H2O)]2[HPMo12O40(VO)2] 1. Single-cr...A hydrothermal reaction of zinc acetate with molybdenum trioxide, vanadium pentoxide, phosphorus pentoxide and 2,2?-bpy (2,2?-bipyridine) led to the title compound [Zn(2,2?- bpy)2(H2O)]2[HPMo12O40(VO)2] 1. Single-crystal X-ray diffraction revealed that 1 (C40H36- N8O44PV2Zn2Mo12) crystallizes in the triclinic system, space group P1 with a = 11.881(2), b = 12.468(2), c = 12.622(2) ?, α = 71.333(8), β = 74.485(4), γ = 86.896(5)o, V = 1705.8(4) ?3, Mr = 2747.64, Z = 1, Dc = 2.675 g/cm3, μ = 3.201 mm-1, F(000) = 1309, S = 1.070, the final R = 0.0697 and wR = 0.1905 for 5368 observed reflections with I > 2σ(I). Compound 1 is built on a mixed-metal bicapped [HPMo12V2O42] subunit covalently bonded to two [Zn(2,2?-bpy)2(H2O)]2+ clusters via terminal oxygen atoms of the capping V atoms. Each Zn atom is six-coordinated by four nitrogen atoms from two 2,2?-bpy ligands, one terminal oxygen atom from coordinated water mole- cule and another one from the capped {VO} unit.展开更多
A novel compound [(NH_4)_6][Gd_2Mo_(36)O_(112)(H_2O)_(20)]·52H_2O (1) was obtained from the reaction of (NH_4)_6Mo7O24·4H_2O with GdCl3 at pH = 1.32. The X-ray structural analysis reveals that 1 crystallizes...A novel compound [(NH_4)_6][Gd_2Mo_(36)O_(112)(H_2O)_(20)]·52H_2O (1) was obtained from the reaction of (NH_4)_6Mo7O24·4H_2O with GdCl3 at pH = 1.32. The X-ray structural analysis reveals that 1 crystallizes in monoclinic system, space group C2/c, Mr = 6937.77, a = 42.313(1), b=12.924(1), c=26.404(1) ?, β= 127.07(1)o, V=15086.2(6) ? 3, Z = 4, Dc = 2.976g·cm－3, ( = 3.316 mm－1, F(000) = 12963, the final R = 0.0585 and wR = 0.1490 for 5431 observed reflections. It contains a usual structural unit {Mo36}, which is linked to two eight-coordinated Gd3+ cations with the Gd-O distances from 2.31(5) to 2.46(5)展开更多
基金financial support by NSFC(21403033 and 21571031)。
文摘Herein,the electronic structures and electronic circular dichroism(ECD)spectra of the chiral Wells-Dawson(W-D)polyoxoanion[(L,D-C_(6)H_(10)N_(3)O_(2))P_(2)Mo_(18)O_(62)]^(5-)(1a/1b)and chiral polyoxoanion[(L,D-C_(6)H_(10)N_(3)O_(2))PMo_(9)O_(31)(OH_(2))_(3)]^(2-)(2a/2b)are investigated using density functional theory(DFT)and time-dependent DFT(TDDFT)calculations.Compared to the fully oxidized[P_(2)Mo_(18)O_(62)]^(6-)structure,the Mo-Ob bond lengths in the one-electron reduced state,[P_(2)Mo_(18)O_(62)]^(7-),tends to be average.It is reasonable that organic ligands can transfer electrons to POMs and affect their chirality.The energy difference between the chiral L-[P_(2)Mo_(18)O_(62)]^(6-)with D_(3)symmetry and ideal[P_(2)Mo_(18)O_(62)]^(6-)with D_(3h)symmetry is 5.88 kcal mol^(-1),which suggests that chirality inversion may occur from the L-isomer to the D-isomer through the ideal[P_(2)Mo_(18)O_(62)]^(6-)by crossing a small energy barrier.Meanwhile,the interaction energy between the L-isomer and L-histidine ligand is larger than that of L-isomer and D-histidine,which indicates that L,D-[P_(2)Mo_(18)O_(62)]^(6-)is induced and further separated by the chiral histidine.The origins of the chiral polyoxoanion are mainly ascribed to charge-transfer(CT)transitions from the O atoms to Mo atoms or organic ligands to Mo atoms.These results confirm that organic cations have an induced effect on chiral POMs.
基金financial support by the NSFC(21073030 and 21131001)the Program for New Century Excellent Talents in University(NCET-10-318)+1 种基金the Doctoral Fund of the Ministry of Education of China(20100043120007)the Science and Technology Development Planning of Jilin Province(20100104 and 20100320).
文摘The redox and acidic properties of α-Keggin anions[PW_(11)O_(39)ME]^(4−)(M=Nb,Ta;E=O,S,Se)have been investigated by using the density functional theory(DFT)method.The calculated results for the studied clusters are consistent with the hypothesis that the substitution of one O atom by S or Se atoms in polyoxometalates(POMs)modifies the relative energy of the lowest unoccupied molecular orbital,inducing slight changes in the redox properties of POMs.The electronic structures and reduction energies of[PW_(11)O_(39)ME]^(4−)(M=Nb,Ta;E=O,S,Se)confirm that the substitution of one O atom by S and Se atoms in POMs enhances the redox properties,which is in good agreement with the cyclic voltammetry characterization of α-[PW+(11)NbO_(40)]^(4−) and α-[PW_(11)NbSO_(39)]^(4−).The bonding energies for adding the first proton to the anions and for ammonia coordination to the protonated α-[PW_(11)O_(39)NbE]^(4−)(E=O,S,Se)were simulated to study the basicity of external oxygen sites and the acidity.The results show that the protonation energy becomes more positive after substitution by S and Se,indicating that the substitution enhances the acidity of POMs.The adsorption energy of ammonia in the case of α-[PW_(11)O_(39)NbE]^(4−)(E=S,Se)is more negative than that of α-[PW_(11)O_(40)NbO]^(4−),which also provides the same result as mentioned above.
基金financially supported by the National Natural Science Foundation of China(20701005 & 20701006)the Fundamental Research Funds for the Central Universitues,Postdoctoral Station Foundation of Ministry of Education(20060200002)+1 种基金the Testing Foundation of Northeast Normal University(NENU),Science and Technology Creation Foundation of NENU(NENU-STC07009)the Program for Changjiang Scholars and Innovative Research Team in University
文摘Two new compounds with microporous Co3[MnMo9O32].15H2O(1) and Cu3[MnMo9O32].15H2O(2) have been synthesized,and characterized by IR,element analysis,TG and single-crystal X-ray analysis.The structure analyses reveal that compounds 1 and 2 are isostructural.In crystal,the Waugh-type polyoxoanions [MnMo9O32]6-are connected by Co2+ or Cu2+ cations to a 3D open-framework,which possesses channels along the [1 2 2] direction of approximately 8.27 × 11.97 .The photocatalytic performances of compounds 1 and 2 for photodegradation of RhB with UV irradiation have been studied,which show a good photocatalytic activity for photodegradation of RhB.
文摘A novel compound(NH4)2Y(H2O)8[PMo10V2O40]·10H2O has been prepared in an aqueous solution and characterized by elemental analysis,IR,and TG-DTG analysis.X-ray diffraction analysis was carried out on(NH4)2Y(H2O)8[PMo10V2O40]·10H2O single crystal,which crystallizes in the monoclinic system of a space group P21/C with a=0.9871(3)nm,b=1.5424(5)nm,c=2.7924(9)nm,β=94.183(5)°and Z=2.In the compound,a two-dimensional network is constructed by the PMo10V2O405-anion and the Y(H2O)83+cation building blocks via hydrogen bonding exhibiting the porous structure.
基金theNationalNaturalScienceFoundationofChina (No .2 9992 5 90 5 ),theMajorStateBasicResearchDevelop mentProgram (No .G2 0 0 0 0 7810 2)andtheBackboneTeacherPlanoftheMinistryofEducationofChina
文摘By employing electrostatic interaction as driving force, an organic/inorganic composite with positively charged dimethyl dialkyl-chain ammonium surfactants encapsulating negatively charged (NH 4) 12[Mo 36(NO) 4O 108(H 2O) 16]·33H 2O polyoxoanion was prepared. The structure of the novel organic/inorganic hybrid particle with hydrophilic core and hydrophobic shell in a defined stoichiometric ratio was confirmed by element analysis, 1H NMR and FT-IR spectra. The property of the polyoxoanion was changed due to the encapsulation and it can be dissolved in organic solvent such as chloroform, benzene and toluene, but not dissolved in water.
基金supported by the Natural Science Foundation of Tianjin City of China (No.18JCJQJC47700)。
文摘A simple and effective method for constructing highly efficient oxygen reduction catalysts with trace amount of isolated cobalt was firstly developed by the pyrolysis of Co-centered polyoxometalate@metalorganic framework (Co-POM@MOF).The Co-centered polyoxometalate ([Co W_(12)O_(40)]^(6-)) was confined in the well-defined void space of ZIF-8 to achieve homogeneous dispersion of polyoxoanions,where the isolated Co centers were well surrounded by the W-O shell and ZIF-8 framework.The Co-POM@MOF-derived N-doping porous carbon (Co-W-NC) with trace cobalt content was facilely prepared by the pyrolysis of the Co-POM@MOF under Ar atmosphere.The single dispersion of polyoxoanions in the metal-organic framework with complete separation of Co center surrounding by W-O shell and ZIF-8 framework ensures the uniform dispersion of Co atoms,confirmed by the Fourier transform extended X-ray absorption fine structure measurement.The Co-W-NC composite catalysts exhibit high performance for oxygen reduction reactions with a half-wave potential of 0.835 V in 0.1 mol/L KOH solution with excellent durability,which is much superior to that of the control samples derived from the[PW_(12)O_(40)]@ZIF-8,and the commercial Pt/C.This work highlights a new insight for constructing highly efficient catalysts via the introduction of metal-centered polyoxometalate into metal-organic framework following the high temperature treatment process.
基金Project supported by the Natural Science Foundation of Fujian Province (E0310016) the Education Committee Foundation of Fujian Province (JA02176)
文摘A hydrothermal reaction of zinc acetate with molybdenum trioxide, vanadium pentoxide, phosphorus pentoxide and 2,2?-bpy (2,2?-bipyridine) led to the title compound [Zn(2,2?- bpy)2(H2O)]2[HPMo12O40(VO)2] 1. Single-crystal X-ray diffraction revealed that 1 (C40H36- N8O44PV2Zn2Mo12) crystallizes in the triclinic system, space group P1 with a = 11.881(2), b = 12.468(2), c = 12.622(2) ?, α = 71.333(8), β = 74.485(4), γ = 86.896(5)o, V = 1705.8(4) ?3, Mr = 2747.64, Z = 1, Dc = 2.675 g/cm3, μ = 3.201 mm-1, F(000) = 1309, S = 1.070, the final R = 0.0697 and wR = 0.1905 for 5368 observed reflections with I > 2σ(I). Compound 1 is built on a mixed-metal bicapped [HPMo12V2O42] subunit covalently bonded to two [Zn(2,2?-bpy)2(H2O)]2+ clusters via terminal oxygen atoms of the capping V atoms. Each Zn atom is six-coordinated by four nitrogen atoms from two 2,2?-bpy ligands, one terminal oxygen atom from coordinated water mole- cule and another one from the capped {VO} unit.
基金Supported by the Natural Science Foundation of China(21101055,21301049,U1304208)the Natural Science Foundation of Henan Province(122300410106)+1 种基金the Foundation of Education Department of Henan Province(2010B150006)the Students Innovative Pilot Plan of Henan University(2012,2013)
基金the State Education Ministry, the State Personal Ministry, National Natural Science Foundation of China (20073048) and the Chine
文摘A novel compound [(NH_4)_6][Gd_2Mo_(36)O_(112)(H_2O)_(20)]·52H_2O (1) was obtained from the reaction of (NH_4)_6Mo7O24·4H_2O with GdCl3 at pH = 1.32. The X-ray structural analysis reveals that 1 crystallizes in monoclinic system, space group C2/c, Mr = 6937.77, a = 42.313(1), b=12.924(1), c=26.404(1) ?, β= 127.07(1)o, V=15086.2(6) ? 3, Z = 4, Dc = 2.976g·cm－3, ( = 3.316 mm－1, F(000) = 12963, the final R = 0.0585 and wR = 0.1490 for 5431 observed reflections. It contains a usual structural unit {Mo36}, which is linked to two eight-coordinated Gd3+ cations with the Gd-O distances from 2.31(5) to 2.46(5)
