Two 3D supramolecular polymers constructed from an amino acid and a high-nuclear Ln6Cu24 cluster node

The first successful attempt to construct 3D supramolecular frameworks with high-nuclear 3d-4f heterometallic clusters as a node is reported. The self-assembly of Ln3+, Cu2+ and amino acid in solution leads to the formation of two polymers, 35-nuclear complex [Sm6Cu29] 1 with a primitive cubic net-like structure and 36-nuclear complex [Nd6Cu30] 2 with a face-centred cubic network type structure. Glycine and L-proline, respectively, were used as ligands. It should be noted that 2 has a chiral framework. X-ray structure analyses show that 1 crystallizes in the triclinic P1 space group (a=19.6451(8), b=20.4682(8), c=20.7046(8) A, alpha=89.453(1), beta=66.290(1), gamma=68.572(1) degrees, V=7003.0(5) A3 and Z=1) and 2 belongs to the cubic P2(1)3 space group (a=b=c=32.4341(3) A, V=34 119.7(5) A3 and Z=4). Both complexes utilize Ln6Cu24 octahedral clusters as nodes and trans-Cu(amino acid)2 groups as bridges. Electrical conductivity measurements reveal that both polymers behave as semiconductors.     

A series of heterometallic 3d-4f polyoxometalates as single-molecule magnets

Three sandwich-like [Ln₂Fe₂(B-α-FeW₉O₃₄)₂]^10? clusters (Ln₂Fe₄, Ln = Dy (1), Ho (2), and Y (3)) were obtained by reacting Na₉[B-α-SbW₉O₃₃], Ln₂O₃, FeCl₃·6H₂O and KH₂PO₄. The [B-α-FeW₉O₃₄]^11? units were formed via the in situ conversion of lacunary polyoxometalates (POM) [B-α-SbW₉O₃₃]^9? and the Ln³⁺ ions were generated from the slow dissolution of Ln₂O₃, both of which play important roles in the synthesis of Ln₂Fe₄. Ln₂Fe₄ is the first 3d-4f cluster assembled from d-metal heteroatom-containing POM. The Dy₂Fe₄ cluster exhibits single-molecule magnet properties with an 80 K energy barrier in an optimal DC field. Cyclic voltammetry tests and controlled-potential coulometry experiments show that the polyoxometalate Fe heteroatom in clusters 1–3 is also electrochemically active.     

A series of 3d-4f heterometallic frameworks comprising 2D lanthanide-organic layers and diverse Cu-complex pillars

Six novel 3D layer-pillared lanthanide-transition metal coordination polymers,LnCuX(IN)2(Ac)(H2O)(Ln = Tb,X = Br(1);Ln = Er,X = Cl(2)),[LnCuCl(IN)2(Ac)].H2O(Ln = Gd(3);Ln = Eu(4)),and [LnCu2Br2(IN)2(Ac)(H2O)].nH2O(Ln = Dy,n =0(5);Ln = Gd,n = 0.5(6))(IN = isonicotinate,Ac = acetate),have been obtained by linking Ln-organic layers and diverse Cu-complex pillars under hydrothermal conditions.1 and 2 are isostructural and formed by 2D Ln-IN-Ac layers and CuX(IN)2 pillars(X = Br(1),X= Cl(2));3 and 4 are isomorph...     

Syntheses, structures, and properties of high-nuclear 3d-4f clusters with amino acid as ligand: {Gd6Cu24}, {Tb6Cu26}, and {(Ln6Cu24)2Cu} (Ln = Sm, Gd)

Four novel high-nuclear 3d-4f heterometallic clusters were obtained through the self-assembly of Ln(III), Cu(II), and amino acid ligands (2-methylalanine (mAla), glycine (Gly), and L-proline (Pro), respectively). The metal skeleton of cluster 1, [Gd6Cu24(mu3-OH)30(mAla)16(ClO4)(H2O)22].(ClO4)17.(OH)2.(H2O)2(0), may be described as a huge {Gd6Cu12} octahedron connected with 12 additional Cu(II) ions. The structure of cluster 2, Na4[Tb6Cu26(mu3-OH)30(Gly)18(ClO4)(H2O)22].(ClO4)25.(H2O)42, may be described as a {Tb6Cu24} main structure connected with two [Cu(Gly)(H2O)2]+ groups. Compounds {[Ln6Cu24(mu3-OH)30(Pro)12(Ac)6(ClO4)(H2O)13]2Cu(Pro)2}.(ClO4)18.(OH)16.(H2O)55 (Ln= Sm (3), Gd (4)) are 61-nuclear clusters, which represent the largest known 3d-4f clusters so far, the structure can be described as two {Ln6Cu24} octahedral units connected by a trans-Cu(proline)2 bridge. The electrical conductivity measurements reveal that they are temperature-sensitive semiconductors. The magnetic susceptibility measurements display that compound 4 is ferromagnetic.     

A series of three-dimensional 3d–4f heterometallic coordination frameworks based on pyridinedicarboxylic acid

Four new 3d–4f heterometallic coordination polymers [Cu₃Eu₂(2,5-pydc)₆(H₂O)₁₂]·4(H₂O) (1), [Zn₂Eu₂(2,5-pydc)₅(H₂O)₂]·3(H₂O) (2), and [Co₃Ln₂(2,6-pydc)₆(H₂O)₆]·4(H₂O) (Ln = Eu, 3; Dy, 4) (H₂pydc = pyridinedicarboxylic acid) have been synthesized and characterized. All of these compounds have extended 3D coordination frameworks containing supramolecular 1D channels, in which lattice water molecules are located. Hydrogen bonds stabilize the 3D frameworks. Additionally, a study of their fluorescence properties has indicated that compounds 1 and 2 show the characteristic transitions of Eu³⁺. Weak antiferromagnetic interactions are observed in compound 3.     

A family of three-dimensional 3d-4f and 4d-4f heterometallic coordination polymers based on mixed isonicotinate and 2-sulfobenzoate ligands: syntheses, structures and photoluminescent properties

Hydrothermal reactions of isonicotinic acid (Hina), 2-sulfobenzoic acid (H(2)sba), d-block metal salts and lanthanide oxides/hydroxides yielded 17 three-dimensional (3D) 3d-4f and 4d-4f heterometallic coordination polymers (HCPs). They are formulated as [LaAg(sba)(ina)(2)](n) (1), [Ln(2)Ag(2)(sba)(2)(ina)(4)(H(2)O)(2)](n) [Ln = Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10)] and [Ln(2)Cu(2)(sba)(2)(ina)(4)(H(2)O)(2)](n) [Ln = La (11), Pr (12), Nd (13), Sm (14), Eu (15), Gd (16), Tb (17)]. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (XRD), infrared (IR) spectroscopy, elemental analysis (EA), and thermogravimetric analysis (TGA). It reveals that they represent two structural types of 3D HCPs. Furthermore, the investigations of their solid-state photoluminescent (PL) property demonstrate the extraordinary emission behaviors. HCP 1(La-Ag) exhibits tunable blue-to-green PL emissions by variation of excitation light. HCPs 6(Gd-Ag), 11(La-Cu), 12(Pr-Cu) and 16(Gd-Cu) show d(10)-metal-based ligand-to-metal charge transfer (LMCT) or metal-to-ligand charge transfer (MLCT) emissions. HCPs 3(Nd-Ag), 4(Sm-Ag), 5(Eu-Ag), 7(Tb-Ag), 8(Dy-Ag), 13(Nd-Cu), 14(Sm-Cu), 15(Eu-Cu) and 17(Tb-Cu) display characteristic PL emissions of the corresponding Ln(III) ions, while both d(10)-metal-based and 4f-metal-centered emissions are observed in the emission spectra of 4(Sm-Ag), 8(Dy-Ag), 14(Sm-Cu) and 17(Tb-Cu).     

Fluoride bridges as structure-directing motifs in 3d-4f cluster chemistry

The use of kinetically robust chromium(III) fluorido complexes as synthons for mixed 3d-4f clusters is reported. The tendency toward linear {Cr(III)-F-Ln(III)} units dictates the cluster topology. Specifically, we show that reaction of cis-[Cr(III)F(2)(NN)(2)]NO(3) (NN = 1,10-phenanthroline ("phen") or 2,2'-bipyridine ("bpy")) with Ln(NO(3))(3)·xH(2)O produces isostructural series of molecular {Ln(2)Cr(2)} squares (1-9) with linear fluoride bridges. In a parallel fashion, fac-[Cr(III)F(3)L], where L = N,N',N″-trimethyl-1,4,7-triazacyclononane ("Me(3)tacn"), reacts with Nd(NO(3))(3)·6H(2)O to form a fluoride-centered penta-nuclear complex and fac-[Cr(III)F(3)L'], with L' = 1,1,1-tris-((methylamino)methylethane) ("Me(3)tame"), reacts with [Ln(hfac)(3)(H(2)O)(2)] (hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone) to yield an isostructural series of {Ln(3)Cr(2)} (10-14) trigonal bipyramids with no central ligand. The formation of the latter is accompanied by a partial solvolysis of the Cr(III) precursor but without formation of insoluble LnF(3). The magnetic properties of the gadolinium containing clusters allow quantification of fluoride-mediated, antiferromagnetic Gd-Cr exchange interactions of magnitude between 0.14 cm(-1) and 0.71 cm(-1) (? = J(12)?(1)·?(2) formalism) and vanishingly small J(Gd-Gd) of 0.06(0) cm(-1). The large spin and small anisotropy together with weak exchange interactions in the {Gd(3)Cr(2)} (11) cluster give rise to a very large magneto-caloric effect of -ΔS(m) = 28.7 J kg(-1) K(-1) (μ(0)H = 90 to 0 kOe).     

Synthesis and structural characterization of a novel two-dimensional 3d-4f heterometallic coordination framework based on pentanuclear lanthanide cluster

A novel 3d-4f heterometallic coordination polymer, {[Tm₅(μ₃-OH)₂(BDC)₆(IN)₂Cu(H₂O)₂]·(H₂O)₃}_n (1) [BDC = benzene-1,2-dicarboxylate, IN = isonicotinate], has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, FTIR, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. The compound crystallizes in monoclinic system, space group P2₁/c (No. 14), a = 13.7302(5) Å, b = 23.5428(3) Å, c = 21.5789(2) Å, β = 91.491(3)°, V = 6973.0(3) ų, and Z = 4. The structure exhibits unusual two-dimensional Tm-carboxylate layer, which is constructed from the expansion of novel pentanuclear {Tm₅} clusters. More interestingly, the heterometallic Cu(I) ions were successfully planted into such Ln-carboxylate layer by the bifunctional IN bridging ligands, resulting in the formation of an unprecedented 2D heterometallic lanthanide-transition-metal framework.     

A series of 3d-4f heterometallic three-dimensional coordination polymers: syntheses, structures and magnetic properties

Seven lanthanide-cobalt heterometallic three-dimensional coordination polymers: {[Ln(3)Co(2)(BPDC)(5)(HBPDC)(H(2)O)(5)](ClO(4))(2)·mH(2)O}(n) (Ln = Eu (1, m = 10.25), Gd (2, m = 8), Tb (3, m = 9.5), Dy (4, m = 11), Ho (5, m = 10.5), Tm (6, m = 11), Lu (7, m = 10.25); BPDC = 5,5'-dicarboxylate-2,2'-dipyridine anion) were structurally and magnetically characterized. Compounds 1-7 crystallize in the orthorhombic space group Pbca, featuring a 3D sandwich framework. Magnetic properties of 2-6 have been investigated by using DC (direct current) and AC (alternating current) susceptibility measurements. Among these compounds, only compound 4 displays significant frequency dependence, albeit without reaching the characteristic maxima above 2 K, implying slow magnetic relaxation behavior in 4. After the application of a DC field, good peak shapes of AC signals were obtained and the energy barrier ΔE/k(B) = 62.89 K and the preexponential factor τ(0) = 6.16 × 10(-8) s. To our knowledge, 4 has the highest energy barrier in Ln-Co SMM systems hitherto.     

Two-dimensional 3d-4f networks containing planar Co4Ln2 clusters with single-molecule-magnet behaviors

Two novel two-dimensional 3d-4f networks based on planar Co(4)Ln(2) clusters supported by rigid 4'-(4-carboxyphenyl)-2,2':6',2"-terpyridine afford the first examples of high-dimensional networks with 3d-4f clusters behaving as single-molecule magnets.     

3d-4f异金属修饰的缺位Lindqvist型同多酸化合物的合成与表征

在水热条件下,成功合成了一例新的异金属修饰的有机-无机杂化型多金属同多酸簇合物[Cu(en)_2(H_2O)]_4[Ce(W_5O_(18))_2]·4H_2O(1)(en=乙二胺),采用X射线单晶衍射、元素分析、X射线粉末衍射及热重分析对化合物进行了结构分析和基本表征.化合物1属于单斜晶系,P2_1/c空间群,单胞参数为a=2.736 1(2)nm,b=1.452 52(7)nm,c=1.634 53(9)nm,β=97.153(6)°.结构解析表明,化合物1中的中心离子Ce~(4+)与两个同多酸簇块的O原子结合形成八配位的四方反棱柱体,并通过游离的及支撑的[Cu(en)_2(H_2O)]~(2+)进行修饰.值得注意的是,化合物1是首例基于{W_5O_(18)}型同多酸簇块的Cu-Ce异金属修饰型有机-无机杂化的孤立结构.     

Magnetic properties and exchange couplings of one-dimensionally arrayed 4f−3d heterometallic [Ln2Cu2]n compounds

Heterometallic polymeric coordination compounds [{Ln(hfac)₂(CH₃OH)}₂{Cu(dmg)(Hdmg)}₂]_n ([Ln₂Cu₂]_n; Ln = Tb, Ho, and Er; H₂dmg = dimethylglyoxime; Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) were synthesized, and the X-ray crystallographic analysis shows that their structures are isomorphous to those of the known ferrimagnetic [Gd₂Cu₂]_n and [Dy₂Cu₂]_n analogs. The exchange couplings in [Tb₂Cu₂]_n, [Ho₂Cu₂]_n, and [Er₂Cu₂]_n were precisely evaluated by high-frequency EPR and pulsed-field magnetization studies, giving J_Tb?Cu/k_B = ?0.77(2) K, J_Ho?Cu/k_B = ?0.250(12) K and J_Er?Cu/k_B = ?0.149(15) K. They were comparable to those of the Gd and Dy analogs. The absolute value of the exchange coupling parameter monotonically decreases in the order of Gd, Tb, Dy, Ho, and Er.     

A new polyoxometalate-based 3d-4f heterometallic aggregate: a model for the design and synthesis of new heterometallic clusters

A new polytungstoarsenate-based 3d-4f heterometallic aggregate has been synthesized, consisting of three {alpha-AsW10 O 38} fragments bridged by three {Fe-(mu3-O)3-Ce} heterometallic clusters.     

Heterospin systems constructed from [Cu2Ln]3+ and [Ni(mnt)2]1-,2- Tectons: First 3p-3d-4f complexes (mnt = maleonitriledithiolato)

New heterospin complexes have been obtained by combining the binuclear complexes [{Cu(H(2)O)L(1)}Ln(O(2)NO)(3)] or [{CuL(2)}Ln(O(2)NO)(3)] (L(1) = N,N'-propylene-di(3-methoxysalicylideneiminato); L(2) = N,N'-ethylene-di(3-methoxysalicylideneiminato); Ln = Gd(3+), Sm(3+), Tb(3+)), with the mononuclear [CuL(1)(2)] and the nickel dithiolene complexes [Ni(mnt)(2)](q)- (q = 1, 2; mnt = maleonitriledithiolate), as follows: (1)infinity[{CuL(1)}(2)Ln(O(2)NO){Ni(mnt)(2)}].Solv.CH(3)CN (Ln = Gd(3+), Solv = CH(3)OH (1), Ln = Sm(3+), Solv = CH(3)CN (2)) and [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)][Ni(mnt)(2)] (3) with [Ni(mnt)2]2-, [{(CH(3)CN)CuL(1)}(2)Ln(H(2)O)][Ni(mnt)(2)]3.2CH(3)CN (Ln = Gd(3+) (4), Sm(3+) (5), Tb(3+) (6)), and [{(CH(3)OH)CuL(2)}{CuL(2)}Gd(O(2)NO){Ni(mnt)(2)}][Ni(mnt)(2)].CH(2)Cl(2) (7) with [Ni(mnt))(2]*-. Trinuclear, almost linear, [CuLnCu] motifs are found in all the compounds. In the isostructural 1 and 2, two trans cyano groups from a [Ni(mnt)2]2- unit bridge two trimetallic nodes through axial coordination to the Cu centers, thus leading to the establishment of infinite chains. 3 is an ionic compound, containing discrete [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)](2+) cations and [Ni(mnt)(2)](2-) anions. Within the series 4-6, layers of discrete [CuLnCu](3+) motifs alternate with stacks of interacting [Ni(mnt)(2)](*-) radical anions, for which two overlap modes, providing two different types of stacks, can be disclosed. The strength of the intermolecular interactions between the open-shell species is estimated through extended Hückel calculations. In compound 7, [Ni(mnt)(2)](*-) radical anions coordinate group one of the Cu centers of a trinuclear [Cu(2)Gd] motif through a CN, while discrete [Ni(mnt)(2)](*-) units are also present, overlapping in between, but also with the coordinated ones. Furthermore, the [Cu(2)Gd] moieties dimerize each other upon linkage by two nitrato groups, both acting as chelate toward the gadolinium ion from one unit and monodentate toward a Cu ion from the other unit. The magnetic properties of the gadolinium-containing complexes have been determined. Ferromagnetic exchange interactions within the trinuclear [Cu(2)Gd] motifs occur. In the compounds 4 and 7, the [Ni(mnt)(2)](*-) radical anions contribution to the magnetization is clearly observed in the high-temperature regime, and most of it vanishes upon temperature decrease, very likely because of the rather strong antiferromagnetic exchange interactions between the open-shell species. The extent of the exchange interaction in the compound 7, which was found to be antiferromagnetic, between the coordinated Cu center and the corresponding [Ni(mnt)(2)](*-) radical anion, bearing mostly a 3p spin type, was estimated through CASSCF/CASPT2 calculations. Compound 6 exhibits a slow relaxation of the magnetization.     

Heptanuclear 3d-4f cluster complexes with a coaxial double-screw-propeller topology and diverse magnetic properties

Two novel coaxial double-screw-propeller heptanuclear 3d-4f cluster complexes are ferromagnetic: one exhibits a large magnetocaloric effect while the other a magnetic relaxation behavior, depending on the lanthanoid ions used.     

The first coordination compound containing three different types of spin carriers: 2p-3d-4f (TCNQ.-, Cu2+ and Gd3+)

A novel heterospin system, [(CuL)2Gd(TCNQ)2].TCNQ-.CH3OH.2CH3CN, is obtained by reacting the mononuclear complex, [CuL], with gadolinium(III) nitrate, followed by the substitution of the nitrato ions with anionic organic radicals.     

Controlled aggregation of heterometallic nanoscale Cu12Ln6 clusters (Ln = Gd(III) or Nd(III)) into 2D coordination polymers

Discrete dinuclear and polymeric heterometallic copper(II)-lanthanide(III) complexes have been synthesized upon variation of pH and characterized by X-ray diffraction analysis. Reactions of the ligand Htza (tetrazole-1-acetic acid) with copper(II) and lanthanide(III) salts gave dinuclear [CuLn(tza)4(H2O)5Cl] complexes at the low pH of 3.5 and 2D heterometallic coordination polymers with high-nuclearity [{Cu2(OH)2}2{Cu12Ln6(mu3-OH)24(Cl)(1/2)(NO3)(1/2)(tza)12(H2O)18}](NO3)(9).8H2O (Ln = Gd or Nd) at a higher pH of 6.6. The acidity of the reaction solution can cause drastic changes in the structures of the products. In the dinuclear complexes, each pair of adjacent dinuclear molecules is linked through hydrogen bonds and pi-pi stacking interactions, and the whole structure is a hydrogen-bonded three-dimensional cubic net. In the coordination polymers, the connecting nodes are [Cu12Ln6] units, which are interconnected by [Cu2O2] units into two-dimensional structures. Magnetic studies exhibit the existence of weak exchange interactions between the Cu(II) and Ln(III) ions bridged by carboxylate and hydroxy ligands.     

Syntheses and characterizations of a series of novel Ln6Cu24 clusters with amino acids as ligands

With glycine or L-alanine as ligands, a series of novel 3d-4f heterometallic Ln(6)Cu(24) clusters with the formulas of [Sm(6)Cu(24)(mu(3)-OH)(30)(Gly)(12)(Ac)(12)(ClO(4))(H(2)O)(16)].(ClO(4))(9).(OH)(2).(H(2)O)(31) (1) and [Ln(6)Cu(24)(mu(3)-OH)(30)(Ala)(12)(Ac)(6)(ClO(4))(H(2)O)(12)].(ClO(4))(10).(OH)(7).(H(2)O)(34) (2.Ln) (Ln = Tb, Gd, Sm, and La) were synthesized by self-assembly, among which 1 and 2.Tb were characterized by X-ray structure analysis. The metal skeleton of the clusters may be described as a huge [Ln(6)Cu(12)] octahedron (constructed with 6 Ln(III) ions located at the vertices and 12 inner Cu(II) ions located at the midpoints of the edges) connected by 12 additional Cu(II) ions (every 2 are connected to 1 Ln(III) vertex). The temperature dependence of the magnetic susceptibilities of 2.Ln was investigated and was found to vary with the central rare-earth ions. Impedance spectroscopic measurements of 2.Ln reveal that they are ionic conductors.