共查询到20条相似文献,搜索用时 15 毫秒
1.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(8):894-900
In recent years, the design and construction of crystalline coordination complexes by the assembly of metal ions with multitopic ligands have attracted considerable attention because of the unique architectures and potential applications of these compounds. Two new coordination polymers, namely poly[[μ‐trans‐1‐(2‐aminopyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene‐κ2N:N′](μ3‐5‐methylisophthalato‐κ4O1,O1′:O3:O3′)cadmium(II)], [Cd(C9H6O4)(C12H11N3)]n or [Cd(5‐Me‐ip)(2‐NH2‐3,4‐bpe)]n, ( I ), and poly[[μ‐trans‐1‐(2‐aminopyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene‐κ2N:N′](μ2‐5‐hydroxyisophthalato‐κ4O1,O1′:O3:O5)cadmium(II)], [Cd(C8H4O5)(C12H11N3)]n or [Cd(5‐HO‐ip)(2‐NH2‐3,4‐bpe)]n, ( II ), have been prepared hydrothermally by the self‐assembly of Cd(NO3)2·4H2O and trans‐1‐(2‐aminopyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene (2‐NH2‐3,4‐bpe) with two similar dicarboxylic acids, i.e. 5‐methylisophthalic acid (5‐Me‐H2ip) and 5‐hydroxyisophthalic acid (5‐HO‐H2ip). The coordination network of ( I ) is a two‐dimensional sql net parallel to (101). Adjacent sql nets are further linked to form a three‐dimensional supramolecular framework via hydrogen‐bonding interactions. Compound ( II ) is a two‐dimensional (3,5)‐connected coordination network parallel to (010) with the point symbol (63)(55647). As the other reactants and reaction conditions are the same, the structural differences between ( I ) and ( II ) are undoubtedly determined by the different substituent groups in the 5‐position of isophthalic acid. Both ( I ) and ( II ) exhibit good thermal stabilities and photoluminescence properties. 相似文献
2.
通过水热或溶剂热合成的方法制备了3个Cd(Ⅱ)/Co(Ⅱ)/Zn(Ⅱ)配位聚合物[Cd(hbmb)0.5(pta)]n(1),[Co(hbmb)(1,4-bdc)]n(2)和{[Zn2(hbmb)1.5(bptc)(H2O)]·0.5hbmb·3H2O}n(3)(hbmb=1,1''-(1,6-己烷)双-(2-甲基苯并咪唑),H2pta=邻羧基苯乙酸,1,4-H2bdc=1,4-苯二乙酸,H4bptc=3,3'',4,4''-二苯甲酮四羧酸))。单晶结构解析表明配合物1是一个4-连接的二维平面网络,拓扑符号为(44·62)。配合物2是一个4-连接的二维褶皱网络,拓扑符号为(42·6)(42·63·8)。配合物3是一个(3,4,4)-连接的三重穿插网络,拓扑符号为(42·62·82)(4·62)(4·64·8)。其中配合物1属于单斜晶系,空间群为P21/c,a=0.758 32(15) nm,b=1.452 8(3) nm,c=1.911 3(5) nm,β=112.26(3)°,Z=4;配合物2属于单斜晶系,空间群为P21/n,a=1.090 8(2) nm,b=1.873 1(4) nm,c=1.301 9(3) nm,β=91.09(3)°,Z=4;配合物3属于三斜晶系,空间群为P1,a=1.119 6(2) nm,b=1.481 2(3) nm,c=1.926 6(4) nm,α=89.72(3)°,β=87.65(3)°,γ=68.28(3)°,Z=2。 相似文献
3.
The supramolecular terbium complex, {[Tb(SIP)(H2O)5]2(bpy)3(H2O)}n (NaH2SIP= 5-sulfoisophthalic acid monosodium salt and bpy=4,4'-bipyridyl), has been synthesized by the hydrothermal reaction of Tb4O7 with NaH2SIP and bpy at 165 ℃, and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectrum, powder X-ray diffraction and photoluminescence spectrum. It crystallizes in a monoclinic system, space group C2/c, with a= 30.6840(1), b=10.9206(2), c=17.4967(3), β=111.931(1)o, V=5438.65(14)3, Z=4, C46H52N6O25S2Tb2, Mr=1470.90, Dc=1.796 g/cm3, μ=2.747 mm-1, F(000)=2928, the final R= 0.0654 and wR=0.1322 for 3806 observed reflections with I > 2σ(I). In the neutral [Tb(SIP)(H2O)5]2 motif, the Tb(III) ions are linked by the SIP ligands to form a one-dimensional zigzag chain propagating along the c axis. The zigzag chains are linked together by hydrogen bonds and π-π stacking interactions to form a two-dimensional supramolecular framework. The uncoordinated bpy molecules act as pillars to extend the two-dimensional sheets into a distinctive pillared three-dimensional supramolecular structure through O-H···N hydrogen bonds. The photoluminescence of the complex was investigated at room temperature in the solid state. 相似文献
4.
The supramolecular terbium complex, {[Tb(SIP)(H2O)5]2(bpy)3(H2O)}n (NaH2SIP = 5-sulfoisophthalic acid monosodium salt and bpy = 4,4'-bipyridyl), has been synthesized by the hydrothermal reaction of Tb4O7 with NaH2SIP and bpy at 165 ℃, and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectrum, powder X-ray diffraction and photoluminescence spectrum. It crystallizes in a monoclinic system, space group C2/c, with a = 30.6840(1), b = 10.9206(2), c = 17.4967(3) A, β= 111.931(1)°, V = 5438.65(14) A^3, Z = 4, C46H52N6O25S2Tb2, Mr = 1470.90, Dc = 1.796 g/cm^3, p = 2.747 mm^-1, F(000) = 2928, the final R = 0.0654 and wR = 0.1322 for 3806 observed reflections with I 〉 2σ(I). In the neutral [Tb(SIP)(H2O)5]2 motif, the Tb(III) ions are linked by the SIP ligands to form a one-dimensional zigzag chain propagating along the c axis. The zigzag chains are linked together by hydrogen bonds and π-π stacking interactions to form a two-dimensional supramolecular framework. The uncoordinated bpy molecules act as pillars to extend the two-dimensional sheets into a distinctive pillared three-dimensional supramolecular structure through O-H...N hydrogen bonds. The photoluminescence of the complex was investigated at room temperature in the solid state. 相似文献
5.
A new complex, [Cd(Himc)2(H2O)2] 1, obtained from imidazole-4-carboxylatic acid (H2imc) and Cd(ClO4)2·6H2O, has been synthesized. The crystal structure was determined by X-ray diffraction. The title compound crystallizes in the orthorhombic system, space group Pccn, with a = 7.4886(11), b = 11.9667(18), c = 13.550(2) A, V= 1214.3(3) A3, Z = 4, Mr= 370.60, Dc = 2.027 mg/m3, F(000) = 728,μ (MoKa) = 1.829 mm^-1, the final R = 0.0243 and wR = 0.0591 for 1150 unique reflections with I 〉 2σ(I). The cadmium(II) center in the title complex is coordinated with two oxygen and two nitrogen atoms from two bidentate chelated imidazole-4-carboxlate ligands together with two water molecules, giving a distorted octahedral coordination geometry. A one-dimensional hydrogen bonding chain is formed via intermolecular O-H...O hydrogen bonds, and such adjacent chains are further stacked through intermolecular π-π and hydrogen bonding interactions to form a 3D supramolecular framework. Complex 1 exhibits a fluorescent emission band at 290 nm (λex = 236 nm) in the solid state. 相似文献
6.
通过水热法合成两个新的混配的配位聚合物[M(bipy)(Metha)2]n·nH2O(M=Ni,1;Co,2;bipy=4,4’-联吡啶;Metha=甲酸),并对配合物进行了元素分析、红外光谱和X-射线单晶衍射测定。结果表明,2个配合物为单斜晶系,C2/c空间群。配合物1和2具有相似的三维网状结构。配体Metha以2种不同的类型与M2+离子配位,一种是Metha中的2个氧原子作为桥联配位原子,连接着由bipy作为双基配体连接2个不同的金属离子构成的链,另一个Metha中的羧基氧只有1个氧原子与金属离子配位,使配合物构成三维结构。 相似文献
7.
One new complex has been produced under solvothermal reactions of tetrakis(4-pyridyloxymethylene)methane(TPOM) with glutaric acid(GA) in the presence of nitrates of cuprum in DMF/H2O(1:5, v/v), namely, {Cu2(TPOM)·GA)2}n. The complex crystallizes in the monoclinic system, space group P2/c with a = 11.556(4), b = 8.713(3), c = 23.602(9) ?, V = 2376.5(15) ?3, C35H36Cu2N4O12, Mr = 831.76, Z = 2, Dc = 1.162 g·cm-3, F(000) = 856, μ = 0.947mm-1, R = 0.0547 and wR = 0.1718(I 2σ(I)). This complex was characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. It is the first complex synthesized by coordinating with TPOM and catenulate aliphatic polycarboxylate acid ligands. The structural analyses show that the complex is a 2-fold interpenetrating 3D architecture. 相似文献
8.
通过水热法合成两个混配的配位聚合物[M(bipy)(Metha)2]n·nH2O(M=Ni,1;Co,2;bipy=4,4′-联吡啶;Metha=甲酸),并对配合物进行了元素分析、红外光谱和X-射线单晶衍射测定。结果表明,2个配合物为单斜晶系,C2/c空间群。配合物1和2具有相似的三维网状结构。配体Metha以2种不同的类型与M2+离子配位,一种是Metha中的2个氧原子作为桥联配位原子,连接着由bipy作为双基配体连接2个不同的金属离子构成的链,另一个Metha中的羧基氧只有1个氧原子与金属离子配位,使配合物构成三维结构。 相似文献
9.
The title coordination polymer, [Co(bib)(L)].0.5H2O 1 (bib = 1,1'-(1,4-butanediyl)bis(imidazole) and L = 4,4'-oxy(bisbenzoate) has been hydrothermally synthesized and characterized by IR and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group Cc with a = 8.8568(5), b = 19.936(1), c = 26.209(2) γ, y = 97.510(1)°, V= 4587.8(5) A3, Z = 8, CoC24H23N4O5.5, Mr = 514.39, Dc = 1.489 g/cm3, F(000) = 2128, μ(MoKa) = 0.795 mm^-1, R = 0.0419 and wR = 0.1002. Compound 1 exhibits a rare two-fold interpenetrating CdSO4 type topology. The O-H...O hydrogen bonds stabilize the structure of 1. 相似文献
10.
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. 相似文献
11.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(2):166-170
Bifunctional organic ligands are very popular for the design of coordination polymers because they allow the formation of a great diversity of structures. In the title coordination polymer, the new bifunctional inversion‐symmetric ligand 2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalic acid (abbreviated as H2bttpa) links CdII cations, giving rise to the three‐dimensional CdII coordination polymer catena‐poly[diaqua[μ4‐2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalato‐κ4O1:O4:N4:N4′]cadmium(II)], [Cd(C12H6N6O4)(H2O)2]n or [Cd(bttpa)(H2O)2]n. The asymmetric unit consists of half a CdII cation, half a bttpa2− ligand and one coordinated water molecule. The CdII cation is located on a twofold axis and is hexacoordinated in a distorted octahedral environment of four O and two N atoms. Four different bttpa2− ligands contribute to this coordination, with two carboxylate O atoms in trans positions and two triazole N atoms in cis positions. Two aqua ligands in cis positions complete the coordination sphere. The fully deprotonated bttpa2− ligand sits about a crystallographic centre of inversion and links two CdII cations to form a chain in a μ2‐terephthalato‐κ2O1:O4 bridge. This chain extends in the other two directions via the triazole heterocycles, producing a three‐dimensional framework. O—H…O hydrogen bonds and weak C—H…N interactions stabilize the three‐dimensional crystal structure. The FT–IR spectrum, X‐ray powder pattern, thermogravimetric behaviour and solid‐state photoluminescence of the title polymer have been investigated. The photoluminescence is enhanced and red‐shifted with respect to the uncoordinated ligand. 相似文献
12.
Jun Fan Wei‐Guang Zhang Min‐Yu Tan Yu Tang Wei‐Sheng Liu Ning Tang Kai‐Bei Yu 《中国化学》2004,22(6):508-511
The La(III) complex with a new amide‐type tripodal ligand,2,2′.2″‐nitrilotris{[(2′‐benzylaminofomyl)‐phenoxylethyl)amine (L), was synthesized and characterized by X‐ray crystallographic analysis. Crystal data: C48H55.50LaN7O18.75, Mr=1169.40, monoclinic. space group, P21/n, a= 1.0644(3) nm. b=2.3889(5) nm, c= 2.1917(5) nm, β=90.65°, V=5.573(2) nm3, Z=1, Dc=1.394 g°cm?3, R1=0.0487, wR [1>2s?(I)]=0.1266. The results reveal that each La(III) ion binds to 9 oxygen atoms, three of which belong to carbonyl groups from three tripodal ligands and six to three bidentate nitrate groups and a two‐dimensional sheet of 4.82 networks is assembled by metal‐ligand coordination interaction. L, a heptadentate compound, merely acts as a tridentate bridging spacer due to its steric hindrance and links the La(III) ions as three‐connected nodes. 相似文献
13.
Amide-type tripodal ligands have been used as ac-tive materials in ion-selective electrodes, ion recogni-tion and ion-transfer carrier, etc.,1-3 but their lanthanide complexes have not yet attracted much attention in spite of their high tendency to coordinate towards Ln(III) ions. The first three dimensional network of Eu(III) complex, which contains 1,1,1-tris{[(2-benzylaminoformyl)- phenoxy]methyl}propane (the hexadentate ligand) and Eu(NO3)3 as building block, assembled by coordination … 相似文献
14.
Xiangning Liu Hua Cai Ruikang Zhou Yaqi Li 《Acta Crystallographica. Section C, Structural Chemistry》2023,79(7):263-268
<!?tlsb=-0.04pt>A new PbII coordination polymer, poly[0.75(aqua)[μ3-4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoato-κ5O,O′;N;O′′,O′′′]]lead(II)] 1.25-hydrate], {[Pb(C20H12N4O4)(H2O)0.75]·1.25H2O}n or {[Pb(L)(H2O)0.75]·1.25H2O}n ( 1 ) [H2L = 4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoic acid], was synthesized under solvothermal reaction conditions and characterized using microanalysis, IR spectroscopy and thermogravimetric analysis. Single-crystal structure analysis reveals that a two-dimensional corrugated layer structure is formed in 1 and that neighbouring layers are further extended into a three-dimensional structure by hydrogen-bonding interactions. In addition, a fluorescence sensing experiment towards Cu2+ based on the polymeric PbII complex was carried out. 相似文献
15.
A Ni(Ⅱ) supramolecular complex,[Ni 2 (btec)(3py) 2 (H 2 O) 8 ](H 2 O) 4 (1),has been synthesized by Ni(ClO 4) 2 ·6H 2 O,benzene-1,2,4,5-tetracarboxylic acid (H 4 btec) and terminal ligand 3-hydroxypyridine (3py) in aqueous solution.The title compound crystallizes in triclinic system,space group P1,with a=8.5637(12),b=9.4138(13),c=10.3611(14),α=67.9540(10),β=85.1740(10),γ=76.9890(10)°,V=754.33(18) 3,Z=2,M r=386.96,D c=1.704 Mg/m 3,μ=1.345 mm-1,F(000)=402,the final R=0.0222 and wR=0.0563 for 2675 observed reflections with I > 2σ(Ⅰ).The adjacent discrete molecules are further self-assembled by intermolecular π-π and O-H···O hydrogen bonding interactions to construct a 3D supramolecular framework.Magnetic measurement shows weak ferromagnetic interaction in the range of 2~300 K. 相似文献
16.
聚合物[Zn(pht)(pzH)2]n的合成,晶体结构与荧光性质 总被引:2,自引:2,他引:2
A Zn(Ⅱ) coordination polymer [Zn(pht)(pzH)2]n (where pht2-=dianion of o-phthalic acid, pzH=pyrazole) has been synthesized and the structure was determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c, a=0.821 39(10) nm, b=1.662 2(2) nm, c=1.156 42(14) nm, β=100.349(2)°, V=1.5532(3) nm3, Z=4. Both carboxylate groups of the phthalate dianion coordinated in a monodentate mode bridged two Zn(Ⅱ) atoms forming the structure of 1-D chain. The pyrazole ligands play two different roles: one only coordinates the metal atom and the other joins the coordination polymer into a 2-D sheet via N-H…O and C-H…O hydrogen bonds besides the coordination property. A blue photoluminescence peak at 435 nm was observed in solid state at room temperature. CCDC: 227946. 相似文献
17.
A new complex {[Mn2(IP)2(1,4-bdc)2]·H2O}n(1)(IP = 1H-imidazo[4,5-f][1,10]-phenanthroline, 1,4-H2 bdc = 1,4-benzendicarboxylic acid), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group Cc with a = 20.326(2), b = 24.249(2), c = 7.621(1), β = 108.546(6), V = 3561.2(7)3, Z = 4, Dc = 1.672 g/cm3, μ = 0.785 mm-1, F(000) = 1824, S = 1.067, the final R = 0.0299 and wR = 0.0752. Compound 1 possesses a 2D structural motif, in which two crystallographically independent 1,4-bdc dianions adopt the alternative mode of mixed bis(bidentate) and monodentate-bidentate coordination modes to bridge neighboring Mn(II) centers. And the 2D layers are linked up by hydrogen bonding and π···π stacking interactions to form a 3D network. The title compound has good thermal stability and exhibits photoluminescent emission maximum at 518 nm. 相似文献
18.
Reactions of M(Ⅱ) acetate (M = Cu, Ni) with disodium 4,4'-biphenyldisulfonate (BPDS) and 2,2'-bipyridine (2,2'-bipy) yielded three new metal sulfonates formulated as {[Cu2(2,2'-bipy)2(H2O)(C2O4)(BPDS)]·2H2O}n 1, [Cu(2,2'-Bipy)(H2O)3](BPDS)'2H2O 2 and [Ni(2,2'-Bipy)(H2O)4](BPDS)·2.5H2O 3. These three compounds were characterized by elemental analyses, FT-IR spectra, TG-DTA analyses and single-crystal X-ray diffraction analyses. Compound 1 belongs to the monoclinic system, space group P21/c with a = 17.7942(2), b = 10.1369(10), c = 19.8681(3) A, β = 104.323(10)°, V = 3472.20(7)A3, Mr = 893.82, Z = 4, F(000) = 1824,μ(CuKa) = 3.295 mm-1, R = 0.0427 and wR = 0.1278. Compound 2 is of orthorhombic system, space group Pca21 with a = 20.1016(7), b = 7.2460(2), c = 17.4802(6)A, V= 2546.10(14)A3, Mr = 622.11, Z= 4, F(000) = 1284,μ (CuKα) = 3.314 mm-1, R = 0.0415 and wR = 0.1291. Compound 3 belongs to the monoclinic system, space group C2/c with a = 15.9204(5), b = 11.7511(4), c = 15.2559(4)A, β = 98.886(3)°, V = 2819.85(15)A3, Mr = 1288.60, Z = 2, F(000) = 1340,μ(CuKa) = 2.957 mm^-1, R = 0.0515 and wR = 0.1454. Compound 1 is composed of one-dimensional helical chains of [Cu2(2,2'-bipy)2(H2O)(C2O4)]2+ fragments bridged alternately by 4,4'-biphenyldisulfonate ligands, along the c axis of the unit cell. In compound 2, 4,4'-biphenyldisulfonate anions are arranged in a zigzag mode and interact with the lattice waters via hydrogen bonds resulting in the formation of infinite chains. Adjacent chains are linked by lattice waters to form 2D extended sheets. The complex cations are located in the interlayer regions and interact with the sheets through hydrogen bonds. In compound 3, the Ni center resides at a crystallographic inversion center and adopts a distorted octahedral coordination sphere. The complex cations interact with 4,4'-biphenyldisulfonate 相似文献
19.
SUN Ya-Guang RONG Shu-Ting WU Yong-Li YU Wan WANG Chuan-Sheng ZHANO Wan-Zhong GAO En-Jun 《结构化学》2009,28(9)
The 1-D chain coordination complex of {[Mn2(HCAM)3(H2bipy)]·5H2O}n(H3CAM=4-hydroxypyridine-2,6-dicarboxylic acid,bipy=4,4′-bipyridine) has been synthesized by the reaction of 4-hydroxypyridine-2,6-dicarboxylic acid,4,4′-bipyridine and manganese carbonate under hydrothermal conditions,and its crystal structure was determined by X-ray diffraction method.The crystal belongs to the monoclinic system,space group P21/n with a=10.110(2),b=20.159(4),c=17.861(4) ,β=99.67(3)°,V=3.5884(12) nm3,Mr=901.47,Z=4,Dc=1.669 g·cm-3,μ=0.798 mm-1,F(000)=1840,the final R=0.0713 and wR=0.1853.The complex forms a 1-D chain bridged by HCAM,protonated 4,4-bipyridines link the 1-D chains to construct 2-D networks via N-H…O hydrogen bonds,and networks are further extended via π-π stacking and hydrogen bonds into 3-D supramolecular framework. 相似文献
20.
The complex [Cu2(H2dhbd)2(tpy)2]·CH3OH·4H2O1 (H4dhbd=2,3-dihydroxybutane-dioic acid, tpy=2,2:6',2-terpyddine) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. The crystal is of triclinic, space groups P1 with a=8.6859(17), b=11.223(2), c=12.275(2)A,α=112.454(3), β=98.435(3),γ=105.593(3)°, V=1022.5(3) A3, Z=1, C38H42Cu2N6.O18, Mr=997.86, Dc=1.621 g/cm3,μ=1.127 mm-1, F(000)=514, T=293(2) K, the final R=0.0539 and wR=0.1394 for 3550 observed reflections with 1 >20(1). In the dinuclear unit, two CuⅡ atoms are bridged by two H2dhbd chelate anions, forming a 14-membered ring, in which the distance of Cu…Cu atoms is 7.0526(12)A. Adjacent dinuclear units are constituted through π-π interactions and C-H…O hydrogen-bonding interactions, fashioning the final 3-D supramolecular framework with 1-D open channels. Variable-temperature magnetic susceptibility measurement indicates the presence of weak antiferromagnetic exchange interactions between CuⅡ ions. 相似文献