Two new transition metal compounds, [Mn（dpa）2（tmd）2]n （1, H2dpa = 4-hydroxy-phenyl-acetic acid, tmd = 4,4-trimethylenedipyridine） and [Co4（dpa）6（tmd）4（H2O）4]n·nH2O·nCl2 （2）, have been synthesiz...Two new transition metal compounds, [Mn（dpa）2（tmd）2]n （1, H2dpa = 4-hydroxy-phenyl-acetic acid, tmd = 4,4-trimethylenedipyridine） and [Co4（dpa）6（tmd）4（H2O）4]n·nH2O·nCl2 （2）, have been synthesized by hydrothermal synthesis. Compound 1 crystallizes in the monoclinic system, space group P21/n with a = 9.828（3）, b = 17.493（5）, c = 11.616（4）, β = 110.146（6）o, V = 1874.9（10）3, C42H42MnN4O6, Mr = 753.74, Z = 2, Dc = 1.335 g/cm3, μ = 0.406 mm-1, F（000） = 790, the final R = 0.1047 and wR = 0.2021 for 2698 observed reflections （I 〉 2σ（I））. Compound 2 crystallizes in the monoclinic system, space group P21/c with a = 11.7214（13）, b = 17.1582（19）, c = 24.625（3）, β = 103.055（3）o, V = 4824.4（9）3, C100H104Cl2Co4N8O23, Mr = 2094.55, Z = 2, Dc = 1.443 g/cm3, μ = 0.809 mm-1, F（000） = 2180, the final R = 0.0550 and wR = 0.0673 for 4104 observed reflections （I 〉 2σ（I））. These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. The structural analyses show that the two compounds are both one-dimensional chain structures. However, compounds 1 and 2 form threedimensional supramolecular structures by hydrogen bonds, respectively.展开更多
Three complexes obtained by the reaction of Pr（Ⅲ） or Nd（Ⅲ） salts with 5-methyl-2-pyrazinecarboxylic acid（Hmpca） are structurally determined by single-crystal X-ray diffraction.Complex [Pr（mpca-）3（H2O）2]2&#...Three complexes obtained by the reaction of Pr（Ⅲ） or Nd（Ⅲ） salts with 5-methyl-2-pyrazinecarboxylic acid（Hmpca） are structurally determined by single-crystal X-ray diffraction.Complex [Pr（mpca-）3（H2O）2]2·6H2O（1） is composed of dinuclear Pr（Ⅲ） units with two metal centers bridged by two anionic mpca-ligands in a κ^3O,O＇：O＇ bridging mode.Complexes [Pr（mpca-）3]n（2） and [Nd（mpca-）3]n（3） are isostructures,and they consist of polymeric chains based on Ln（Ⅲ） and mpca-ligands.Each pair of adjacent metal centers is linked by three mpca-molecules in a κ^3N,O：O bridging mode.展开更多
The effect of Dy doping on magnetism of La 0.7 Sr 0.3 CoO 3 system was studied through the measurements of M-T curves and M-H curves. The results show that with Dy content increasing, T C decreases, M weakens, the coe...The effect of Dy doping on magnetism of La 0.7 Sr 0.3 CoO 3 system was studied through the measurements of M-T curves and M-H curves. The results show that with Dy content increasing, T C decreases, M weakens, the coercive force strengthens, and the samples exhibit the abnormal phenomenon that M increases continuously with T decreasing in low temperature range. Research indicates that the variation of magnetism in the system comes from the changes of lattice parameters and magnetic environment caused by Dy doping and from the spin-state transition of Co ions induced by Dy ions.展开更多
The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman s...The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.展开更多
基金Supported by the Natural Science Foundation of Anhui Province (090416239)the Science and Technology Play (?) Projects of Anhui Province (09020203071)+2 种基金the National Natural Science Foundation of China (20871089)the Foundation of Anhui Provincial Education Department for Outstanding Young Talents in University (2009SQRZ172)the Scientific Research Foundation for the Professors (Doctors) of Suzhou University (2010jb01)
文摘Two new transition metal compounds, [Mn（dpa）2（tmd）2]n （1, H2dpa = 4-hydroxy-phenyl-acetic acid, tmd = 4,4-trimethylenedipyridine） and [Co4（dpa）6（tmd）4（H2O）4]n·nH2O·nCl2 （2）, have been synthesized by hydrothermal synthesis. Compound 1 crystallizes in the monoclinic system, space group P21/n with a = 9.828（3）, b = 17.493（5）, c = 11.616（4）, β = 110.146（6）o, V = 1874.9（10）3, C42H42MnN4O6, Mr = 753.74, Z = 2, Dc = 1.335 g/cm3, μ = 0.406 mm-1, F（000） = 790, the final R = 0.1047 and wR = 0.2021 for 2698 observed reflections （I 〉 2σ（I））. Compound 2 crystallizes in the monoclinic system, space group P21/c with a = 11.7214（13）, b = 17.1582（19）, c = 24.625（3）, β = 103.055（3）o, V = 4824.4（9）3, C100H104Cl2Co4N8O23, Mr = 2094.55, Z = 2, Dc = 1.443 g/cm3, μ = 0.809 mm-1, F（000） = 2180, the final R = 0.0550 and wR = 0.0673 for 4104 observed reflections （I 〉 2σ（I））. These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. The structural analyses show that the two compounds are both one-dimensional chain structures. However, compounds 1 and 2 form threedimensional supramolecular structures by hydrogen bonds, respectively.
基金Supported by the National Natural Science Foundation of China (Nos. 20971065,20771005)National Basic Research Program of China (2007CB925103)+1 种基金the Young Teachers Program of College in Anhui Province (2008jql138)the Natural Science Foundation of Anhui Province (090416239)
文摘Three complexes obtained by the reaction of Pr（Ⅲ） or Nd（Ⅲ） salts with 5-methyl-2-pyrazinecarboxylic acid（Hmpca） are structurally determined by single-crystal X-ray diffraction.Complex [Pr（mpca-）3（H2O）2]2·6H2O（1） is composed of dinuclear Pr（Ⅲ） units with two metal centers bridged by two anionic mpca-ligands in a κ^3O,O＇：O＇ bridging mode.Complexes [Pr（mpca-）3]n（2） and [Nd（mpca-）3]n（3） are isostructures,and they consist of polymeric chains based on Ln（Ⅲ） and mpca-ligands.Each pair of adjacent metal centers is linked by three mpca-molecules in a κ^3N,O：O bridging mode.
基金supported by the Key Programme of Grand Basic Research Programme of China (No.2007CB925001)the National Key Basic Research Programme of China (No. 001CB610604)the Grand Natural Science Research Programme of Anhui Education Department (Nos. ZD2007003-1 and KJ2010A074)
文摘The effect of Dy doping on magnetism of La 0.7 Sr 0.3 CoO 3 system was studied through the measurements of M-T curves and M-H curves. The results show that with Dy content increasing, T C decreases, M weakens, the coercive force strengthens, and the samples exhibit the abnormal phenomenon that M increases continuously with T decreasing in low temperature range. Research indicates that the variation of magnetism in the system comes from the changes of lattice parameters and magnetic environment caused by Dy doping and from the spin-state transition of Co ions induced by Dy ions.
基金the Key Programme of Grand Basic Research Programme of China(No.2007CB925001)the National Key Basic Research Programme of China(No.001CB610604)+1 种基金the Grand Natural Science Research Programme of Anhui Education Department(Nos.ZD2007003-1 and KJ2010A074)the Anhui Provincial Natural Science Foundation(No.1308085MA11)。
文摘The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.
