Spontaneous Resolution of a Mixed-Ligand Nickel(II) Coordination Polymer with Achiral Precursors

Metal-center-driven spontaneous resolution of a chiral coordination polymer, [Ni(SDB)(BIX)](n) (1), from achiral precursors has been probed by single-crystal X-ray diffraction and circular dichroism spectroscopy. Enantiomorphs 1P and 1M showed a parallel interpenetrated 2D → 3D chiral framework with (8(2).10) topology. Switching of the metal center under the same reaction parameters resulted in isostructural achiral and noninterpenetrating (4,4) grid-type sql networks [M(SDB)(BIX)](n), where M = Co(II), Zn(II), and Cd(II) for 2-4, respectively.     

Photochemical [2 + 2] cycloaddition as a tool to study a solid-state structural transformation

The solid-state structural transformation of the hydrogen-bonded 1D coordination polymer [Cd(bpe)(CH(3)COO)(2)(H(2)O)](n), to a ladder-type structure is evident from a photochemical [2 + 2] cycloaddition reaction forming 100% rctt-cyclobutane isomer.     

Synthesis of a series of 4-pyridyl-1,2,4-triazole-containing cadmium(II) luminescent complexes

Using two 4-substitued triazole ligands, 4-(pyrid-2-yl)-1,2,4-triazole (L(1)) and 4-(pyrid-3-yl)-1,2,4-triazole (L(2)), a series of novel triazole-cadmium(II) complexes varying from zero- to three-dimensional have been prepared and their crystal structures determined via single-crystal X-ray diffraction. [Cd(2)(micro(2)-L(1))(3)(L(1))(2)(NO(3))(mu(2)-NO(3))(H(2)O)(2)](NO(3))(2).1.75H(2)O (1) is a binuclear complex containing bidendate, monodedate and free nitrate anions. When the bridging anions SCN(-) and dca (dca = N(CN)(2)(-)) were added to the reaction system of 1, one-dimensional (1D) [Cd(L(1))(2)(NCS)(2)](n) (2) and two-dimensional (2D) [Cd(L(1))(2)(dca)(2)](n) (3) were isolated, respectively. When L(2) instead of L(1) was used, [Cd(L(2))(2)(NCS)(2)(H(2)O)(2)] (4) and 1D [Cd(L(2))(2)(dca)(2)](n) (5) were obtained. When the ratio of Cd to L(2) was changed from 1:2 to 1:1 in the reaction system of 5, three-dimensional (3D) {[Cd(3)(micro(2)-L(2))(3)(dca)(6)].0.75H(2)O}(n) (6) with 1D microporous channels along the a direction was isolated. Further investigations on other Cd(ii) salts and the L(2) ligand in a Cd to L(2) ratio of 1:1, an unexpected complex [Cd(mu(2)-L(2))(mu(3)-SO(4))(H(2)O)](n) (7) with a 3D open framework was obtained. All of the complexes exhibit strong blue fluorescence emission bands in the solid state at ambient temperature, of which the excitation and emission maxima are red-shifted to longer wavelength as compared to those in water. Powder X-ray diffraction and thermal studies were used to investigate the bulk nature of the 3D coordination polymers 6 and 7.     

Hydrothermal syntheses, crystal structures, and characteristics of a series of Cd-btx coordination polymers (btx = 1,4-Bis(triazol-1-ylmethyl)benzene)

Four novel cadmium-btx (btx = 1,4-bis(triazol-1-ylmethyl)benzene) coordination polymers [Cd(btx)(2)(NO(3))(2)](n)(1), [Cd(btx)(2)Cl(2)](n)(2), [Cd(btx)(SO(4))(H(2)O)(2)](n)(3), and [Cd(btx)(S(2)O(7))(H(2)O)](n)(4) have been prepared by hydrothermal reaction (140 or 180 degrees C) and characterized. Both 1 and 2 have two-dimensional rhombohedral grid structures, 3 possesses a two-dimensional rectangular grid structure, and 4 displays a three-dimensional framework, which is formed by btx bridging parallel layers. To the author's best knowledge, polymer 4 is the first Cd(II) polymer in which the Cd(II) ion is eight-coordinated in a hexagonal bipyrimidal geometry. In addition, we studied the effects of temperature on the hydrothermal reaction system of btx and CdSO(4) and found that different products can be obtained at different temperatures. Furthermore, polymer 3 possesses a very strong third-order NLO absorptive effect with an alpha(2) value of 1.15 x 10(-)(9) m W(-1). Polymers 2-4 display strong fluorescent emissions in the solid state at room temperature. The DTA and TGA results of the four polymers are in agreement with the crystal structures.     

Design and construction of coordination polymers based on 2,2'-dinitro-4,4'-biphenyldicarboxylate and semi-rigid N-donor ligands: diverse structures and magnetic properties

Eight 2D and 3D coordination polymers, [Mn(NBPDC)(1,4-bimb)](n) (1), [Zn(NBPDC)(1,4-bimb)](n) (2), [Cd(NBPDC)(1,4-bimb)](n) (3), [Mn(2)(NBPDC)(2)(1,3-bimb)(H(2)O)](n) (4), {Zn(NBPDC)(1,3-bimb)}(n) (5), [Cd(2)(NBPDC)(2)(1,3-bimb)(2)(H(2)O)](n) (6), [Mn(NBPDC)(4,4'-bimbp)](n) (7), and [Cd(2)(NBPDC)(2)(4,4'-bimbp)(2)](n) (8), (NBPDC = 2,2'-dinitro-4,4'-biphenyldicarboxyl acid, 1,4-bimb = 1,4-bis(imidazol-1-ylmethyl) benzene, 1,3-bimb = 1,3-bis(imidazol-1-ylmethyl) benzene, and 4,4'-bimbp = 4,4'-(bis(imidazol-l-ylmethylene)) biphenyl), have been prepared and structurally characterized. In these coordination polymers, NBPDC and three N-donor ligands link different metal ions and SBUs to construct diverse architectures. Compounds 1 and 3 are isomorphic, showing a two-fold interpenetrating pcu topology. Compound 2 presents a 2D (4, 4) net. Compound 4 is a hex framework built by the linkage of ligands with infinite rod-shaped SBUs. Compound 5 presents a unprecedented eight-fold interpenetrating sra topology. Compound 6 exhibits a unique 2D {6(3)}{6(5).8} topology with four-fold interpenetrating structure. Compound 7 presents a 3D hex topology, and compound 8 shows a (4, 4) net. The magnetic properties of compounds 1, 4, and 7 have been characterized. Compound 1 displays interesting spin-canting antiferromagnetism and metamagnetism simultaneously. Compound 7 exhibits spin-canting antiferromagnetism.     

(infinity)(2)[Cu2(mu5-btb)(mu-OH)(mu-H2O)]: a two-dimensional coordination polymer built from ferromagnetically coupled Cu2 units (btb = benzene-1,2,3-tricarboxylate)

Hydrothermal reaction of Cu(NO(3))(2).3H(2)O, Cd(OH)(2) or Zn(OH)(2) with benzene-1,2,3-tricarboxylic acid (H(3)btb, hemimellitic acid) produced the 2D coordination polymer (MOF) [Cu(2)(mu(5)-btb)(mu-OH)(mu-H(2)O)] () and the 2D hydrogen-bonded complexes [Cd(H(2)btb)(2)(H(2)O)(4)].2H(2)O () and [Zn(H(2)O)(6)](H(2)btb)(2).4H(2)O () which are characterized by single-crystal X-ray diffraction, X-ray powder diffraction and thermoanalysis. Magnetic susceptibility measurements between 1.9-300 K for revealed three magnetic active exchange pathways that link the copper(ii) ions through a long mu-aqua bridge, an anti-syn carboxylate bridge [j(2) = 0.161(1) cm(-1)], and through a mixed mu-hydroxo + syn-syn carboxylate bridge [J = 83(1) cm(-1)]. At temperatures higher than 30 K the system behaves as isolated Cu(2) units with strong ferromagnetic Cu-Cu coupling through the mu-hydroxo and syn-syn carboxylate bridge. The strong ferromagnetic coupling is explained with Hoffmann's approach by means of the concept of counter-complementarity introduced by Nishida et al.[Chem. Lett., 1983, 1815-1818].     

Synthesis, crystal structure and luminescent properties of one 3D Cd(II) coordination polymer [Cd(H3BPTC)2(bpy)]n (H4BPTC = 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid, bpy = 4,4'-bipyridine)

A new 3D metal-organic coordination polymer [Cd(H(3)BPTC)(2)(bpy)](n) (1) (H(4)BPTC = 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid, bpy =4,4'-bipyridine) has been synthesized and characterized by single X-ray diffraction and IR spectroscopy. The one-dimensional metal-organic chains of the title complex, namely [Cd(H(3)BPTC)(2)](n), are held together through hydrogen bonding and bridging "second" ligand 4,4'-bpy to give a three-dimensional metal-organic network. The thermal stability of complex 1 was studied by thermal gravimetric (TG) and differential thermal analysis (DTA). Compound 1 exhibits photoluminescence with an emission maximum at ca. 380 nm upon excitation at ca. 251 nm.     

Variation in the coordination mode of arenedisulfonates: syntheses and structural characterization of mononuclear and dinuclear cadmium(II) arenedisulfonate complexes with two- to zero-dimensional architectures

Seven cadmium(II) arenedisulfonate compounds, namely [Cd(2,2'-bpy)(2)(H(2)O)(peds)].4H(2)O (1), [Cd(2)(2,2'-bpy)(4)(H(2)O)(2)(1,5nds)](1,5nds).4H(2)O (2), [Cd(cyclam)(1,5nds)](2) (3), ([Cd(inia)(2)(H(2)O)(2)(2,6nds)].4H(2)O)(n)(4), ([Cd(inia)(2)(H(2)O)(2)(bpds)].4H(2)O)(n)(5), ([Cd(2)(inia)(4)(H(2)O)(3)(peds)(2)].2H(2)O)(n)(6), and [Cd(1,5nds)(H(2)O)(2)](n) (7), where 2,2'-bpy = 2,2'-bipyridyl, cyclam = 1,4,8,11-tetraazacyclotetradecane, inia = isonicotinamide, nds = naphthalenedisulfonate, bpds = 4,4'-biphenyldisulfonate, and peds = 4,4'-phenyletherdisulfonate, have been obtained from aqueous solution by using similar procedures and structurally characterized by X-ray single-crystal diffraction, IR spectroscopy, and thermal gravimetric analysis. In 1, the peds anion coordinates as a monodentate ligand, leading to a mononuclear unit. In 2 and 3, the 1,5nds anions coordinate as mu(2)-bridging ligands in different modes, producing charged or neutral dinuclear clusters. In 4 and 5, 2,6nds and bpds behave as mu(2)-spacers, resulting in 1-dimensional polymers. While in 6, the peds acts both as terminal and bridging ligands with the SO(3)(-) groups being either monodentate or mu(2)-bridging, creating a knotted 1-dimensional polymer with dinuclear clusters as the repeating units. In 7, 1,5nds acts as a bridging ligand with each SO(3)(-) coordinated as a mu(2)-bridging group to adjacent Cd(II) centers, leading to a 2-dimensional polymer. Together with the reported ([Cu(en)(2)(1,5nds)].2H(2)O)(n) (8), all of the six possible coordination modes adopted by organodisulfonate anions, on the assumption that each SO(3)(-) group could be monodentate or mu(2)-bridging, are realized by introducing nitrogen-containing organic ligands as auxiliaries.     

New types of the flexible self-assembled metal-organic coordination polymers constructed by aliphatic dicarboxylates and rigid bidentate nitrogen ligands

The reaction of metal ions, flexible aliphatic dicarboxylates and rigid bidentate linear ligands under mild conditions in water afford four novel metal-organic coordination polymers, [Cd(mu-mal)(mu-pyz)(0.5)(H(2)O)](n) 1 (mal = malonate dianion, pyz = pyrazine), [Cd(2)(mu-suc)(2)(mu-pyz)(H(2)O)(2)](n) 2 (suc = succinate dianion), and ([M(mu-bipy)(H(2)O)4][suc].4H(2)O)(n)(M = Co, 3, M = Zn, 4, bipy = 4,4'-bipyridine). The molecular structures of 1-4 have been established by single-crystal X-ray crystallography. 1 is a 3D network being composed of layers of octahedrally coordinated Cd atoms bridged by malonate anions in syn-anti configurations within the layers and pyz molecules between layers. Unlike that in 1, each Cd atom in 2 displays uncommon pentagonal-bipyramidal geometry to form 2D infinite grid sheets with square grid dimensions of ca. 7.936 x 7.936 [Angstrom]. Both 3 and 4 exhibit 1D linear -M-bipy-M-bipy- chain polymers, and these chains were packed as ...ABCABC... layered structures. The bridging succinate ligands in 2 adopt the syn-anti mode with a torsion angle of 60.8(7) degrees, while the solvated succinate ligands in 3 and 4 adopt the anti-anti mode with a torsion angle of 180.0 degrees. To our knowledge, compound 2 represents the first example of flexible self-assembled succinate-pyrazine mixed bridging ligand coordination network. 3 and 4 are the first two cases of succinate-bipy polymers with non-coordinated succinate. The magnetic behavior for 3 was studied in the temperature range of 5-300 K. The result indicates the occurrence of a weak antiferromagnetic coupling between the cobalt(II) ions.     

Synthesis, structural diversity and fluorescent characterisation of a series of d10 metal-organic frameworks (MOFs): reaction conditions, secondary ligand and metal effects

Along with our recent investigation on the flexible ligand of H(2)ADA (1,3-adamantanediacetic acid), a series of Zn(II) and Cd(II) metal-organic frameworks, namely, [Zn(3)(ADA)(3)(H(2)O)(2)](n)·5nH(2)O (1), [Zn(ADA)(4,4'-bipy)(0.5)](n) (2), [Zn(2)(ADA)(2)(bpa)](n) (3), [Zn(2)(ADA)(2)(bpa)](n) (4), [Zn(2)(ADA)(2)(bpp)](n) (5), [Cd(HADA)(2)((4,4'-bipy)](n) (6), [Cd(3)(ADA)(3)(bpa)(2)(CH(3)OH)(H(2)O)](n) (7), and [Cd(2)(ADA)(2)(bpp)(2)](n)·7nH(2)O (8) have been synthesized and structurally characterized (where 4,4'-bipy = 4,4'-dipyridine, bpa = 1,2-bis(4-pyridyl)ethane and bpp = 1,3-bis(4-pyridyl)propane). Due to various coordination modes and conformations of the flexible dicarboxylate ligand and the different pyridyl-containing coligands, these complexes exhibit structural and dimensional diversity. Complex 1 exhibits a three-dimensional (3D) framework containing one-dimensional (1D) Zn(II)-O-C-O-Zn(II) clusters. Complex 2 exhibits a 2D structure constructed by 1D double chains based on [Zn(2)ADA(2)] units and a 4,4'-bipy pillar. Complexes 3 and 4 possess isomorphic 2D layer structures, resulting from the different coordination modes of carboxylate group of ADA ligands. Complex 5 features a 2D 4(4) layer in which ADA ligands and Zn(II) atoms construct a 1D looped chain and the chains are further connected by bpp ligands. Complex 6 is composed of 1D zig-zag chains that are entangled through hydrogen-bonding interactions to generate a 2D network. Complex 7 is a rare (3,5)-connected network. Complex 8 possesses a 3D microporous framework with lots of water molecules encapsulated in the channels. The structural diversity of the complexes perhaps mainly results from using diverse secondary ligands and different metal centre ions, and means the assistant ligand and metal centre play important roles in the design and synthesis of target metal-organic frameworks. This finding revealed that ADA could be used as an effective bridging ligand to construct MOFs and change coordination modes and conformational geometries in these complexes. The thermogravimetric analyses, X-ray powder diffraction and solid-state luminescent properties of the complexes have also been investigated.     

由MCl2(M=Zn，Cd)与咪唑-4，5-二羧酸和1，4-双(咪唑-1-基)丁烷构筑的两个二重穿插二维配位聚合物的合成、结构和性质

以2∶1∶4物质的量比的咪唑-4,5-二羧酸(H3IDC),1,4-双(咪唑-1-基)丁烷(bib)和ZnCl2或CdCl2为反应物,在水热条件下分别得到了1个二重穿插的二维锌(Ⅱ)配位聚合物{[Zn2(IDC)(bib)Cl].H2O}n(1)和1个二重穿插的二维镉(Ⅱ)配位聚合物[Cd2(HIDC)(bib)1.5Cl2]n(2)。用元素分析、红外光谱以及单晶X-射线衍射结构分析对它们的组成和结构进行了表征,并对它们的热稳定性和荧光性质进行了初步的研究。     

Auxiliary Ligands Mediated One-and Two-dimensional Cd(Ⅱ) Coordination Polymers Incorporating Methyl-3-hydroxy-5-carboxy-2-Thiophenecarboxylate Ligand

Two N-donor ligands mediated Cd(II) coordination polymers, namely, [Cd(L)(dmpz)_2]_n(1) and {[Cd(L)(atr)_(0.5)(H_2O)](H_2O)}n(_2)(H_2 L = methyl-3-hydroxy-5-carboxy-2-thiophenecarboxylate, dmpz = 3,5-dimethylpyrazole, and atr = 4-amino-1,2,4-triazole), have been produced. Their structures were characterized by single-crystal X-ray diffraction analysis, elemental analyses and infrared spectra. Compound 1 possesses a one-dimensional(1 D) chain structure and is finally extended into a three-dimensional(3 D) supramolecular architecture though hydrogen bonding interactions. Compound 2 features a two-dimensional(2 D) network with 4-connected sql topology based on dinuclear Cd(II) clusters as nodes, which is also assembled into a 3 D supramolecular architecture through hydrogen bonding interactions. Furthermore, compounds 1 and 2 exhibit high thermal stabilities and intense fluorescent emission in the solid, and can be explored as potential luminescent materials.     

Dynamic crystal-to-crystal conversion of a 3D-3D coordination polymer by de- and re-hydration

A reversible crystal-to-crystal transformation of a 3D lead(ii) coordination polymer with the ligand 4-pyridinecarboxylic acid (4-Hpyc), from [Pb(4-pyc)(2)(H(2)O)](n) () to [Pb(4-pyc)(2)](n) () by de- and re-hydration, has been observed and the structures of and were determined by single-crystal X-ray diffraction. The thermal stabilities of compounds and were studied by thermal, gravimetric and differential thermal analyses. Powder X-ray diffraction experiments showed that the phase transitions observed for the single crystals also occur in the batch powder samples and lead to mono phasic products.     

Synthesis, X-ray structures and luminescence properties of three multidimensional metal-organic frameworks incorporating the versatile 5-(pyrimidyl)tetrazolato bridging ligand

The hydrated sodium salt of the novel and versatile 5-(pyrimidyl)tetrazolato ligand (pmtz(-)), Na(pmtz).H(2)O (1), has been prepared in very mild conditions from 2-cyanopyrimidine and NaN(3). Two coordination polymers [Cd(pmtz)(2)]n (2)and [Cd(pmtz)(micro-Cl)(0.5)(micro-N(3))(0.5)(H(2)O)](n)(3), , have been synthesized from (1)under conventional or hydrothermal conditions, respectively, and fully characterized by single-crystal or powder X-ray diffraction methods. Compounds and consist of mono-dimensional polymeric chains, further stabilized by interchain pi-pi stacking and hydrogen bond interactions. Compound , containing octacoordinated Cd ions of crystallographic D(2) symmetry, exhibits neutral (4, 4) layers formed by square units of the metallacalix[4]arene type in 1,3-alternate conformation. Species , and display intense, room temperature, photoluminescence in the solid state.     

Six new metal-organic frameworks based on polycarboxylate acids and V-shaped imidazole-based synthon: syntheses, crystal structures, and properties

Solvothermal reactions of 4,4'-bis(imidazol-1-yl)diphenyl ether (BIDPE) with deprotonated 5-hydroxy-isophthalic acid (5-OH-H(2)bdc), and benzene-1,3,5-tricarboxylic acid (H(3)btc) in the presence of cadmium(II), zinc(II), cobalt(II), nickel(II), and manganese(II) salts in H(2)O or H(2)O/DMF produced six new complexes, namely, [Cd(BIDPE)(5-OH-bdc)·H(2)O](n) (1), [Co(BIDPE)(5-OH-bdc)·H(2)O](n) (2), [Zn(3)(BIDPE)(3)(5-OH-bdc)(3)·4H(2)O](n) (3), [Ni(BIDPE)(2)(5-OH-bdc)(H(2)O)·3H(2)O](n) (4), {[Mn(2)(BIDPE)(2)(5-OH-bdc)(2)](n) (5), and [Ni(BIDPE)(2)(Hbtc)(H(2)O)](n) (6). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compounds 1 and 2 reveal the same two-dimensional (2D) sheets with a 32-membered [(Cd/Co)(2)(BIDPE)(2)] metallocyclic ring constructed from BIDPE and 5-OH-H(2)bdc with Cd or Co salts. For compound 3, six identical 2D sheets are polycatenated in parallel to form a rare 2D → 2D framework; it displays ferroelectric behavior with a remnant electric polarization (P(r)) of 0.033 μC/cm(2) and an electric coercive field (E(c)) of 11.15 kV/cm. In compounds 4 and 6, only one carboxyl group coordinated to the Ni atom from 5-OH-H(2)bdc or H(3)btc. Compound 5 exists as binuclear Mn clusters, which are linked by BIDPE and 5-OH-H(2)bdc to generate a 2D sheet and displays weak antiferromagnetic character. In addition, the thermal stabilities and photochemical properties of these new complexes have been studied.     

Cd2(Te6O13)][Cd2Cl6] and Cd7Cl8(Te7O17): novel tellurium(IV) oxide slabs and unusual cadmium chloride architectures

Initial attempts to prepare new Ln-Cd-Te-O-Cl compounds led to the isolation of two novel cadmium tellurium(IV) oxychlorides with two different types of structures, namely, [Cd(2)(Te(6)O(13))][Cd(2)Cl(6)] and Cd(7)Cl(8)(Te(7)O(17)). Both compounds feature novel polymeric tellurium(IV) oxide anions and unusual cadmium chloride substructures. The structure of [Cd(2)(Te(6)O(13))][Cd(2)Cl(6)] is composed of 1D [Cd(2)Cl(6)](2)(-) double chains and (002) [Cd(2)(Te(6)O(13))](2+) layers. The 1D Te(6)O(13)(2)(-) slab of the [Cd(2)(Te(6)O(13))](2+) layer is formed by TeO(3), TeO(4), and TeO(5) groups via corner- and edge-sharing, and it contains six- and seven-membered tellurium(IV) polyhedral rings. The structure of Cd(7)Cl(8)(Te(7)O(17)) features a 3D network with long-narrow tunnels along the b axis. The two types of structural building blocks are 1D [Te(7)O(17)](6)(-) anions and unusual corrugated [Cd(7)Cl(8)](6+) layers based on "cyclohexane-like" Cd(3)Cl(3) rings.     

Reactions of cadmium(II) nitrate with 4-(trimethylammonio)benzenethiolate in the presence of N-donor ligands

Reactions of Cd(NO(3))(2)·4H(2)O with TabHPF(6) (TabH = 4-(trimethylammonio)benzenethiol) and Et(3)N in the presence of NH(4)SCN and five other N-donor ligands such as 2,2'-bipyridine (2,2'-bipy), phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (2,9-dmphen), 2,6-bis(pyrazd-3-yl)pyridine (bppy) and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (bdmppy) gave rise to a family of Cd(II)/thiolate complexes of N-donor ligands, {[Cd(2)(μ-Tab)(4)(NCS)(2)](NO(3))(2)·MeOH}(n) (1), [Cd(2)(μ-Tab)(2)(L)(4)](PF(6))(4) (2: L = 2,2'-bipy; 3: L = phen), [Cd(Tab)(2)(L)](PF(6))(2) (4: L = 2,9-dmphen; 5: L = bppy), and [Cd(2)(μ-Tab)(2)(Tab)(2)(bdmppy)](2)(PF(6))(8)·H(2)O (6·H(2)O). These compounds were characterized by elemental analysis, IR spectra, UV-Vis spectra, (1)H NMR, electrospray ionization (ESI) mass spectra and single-crystal X-ray diffraction. For 1, each [Cd(NCS)](+) fragment is connected to its equivalents via a pair of Tab bridges to a one-dimensional chain. For 2 and 3, two [Cd(2,2'-bipy)(2)](2+) or [Cd(phen)(2)](2+) units are linked by a pair of Tab bridges to form a cationic dimeric structure. The Cd atom in [Cd(Tab)(2)(L)](2+) dication of 4 or 5 is coordinated by two Tab ligands and chelated by two N atoms from 2,9-dmphen (4) or three N atoms from bppy (5), forming a distorted tetrahedral (4) or trigonal bipyramidal (5) coordination geometry. For 6, each of two [Cd(Tab)(bdmppy)] fragments is linked to one [(Tab)Cd(μ-Tab)(2)Cd(Tab)] fragment via two Tab bridges to generate a unique cationic zigzag tetrameric structure where the Cd centers take a tetrahedral or a trigonal bipyramidal coordination geometry. The results may provide an interesting insight into mimicking the coordination spheres of the Cd(II) sites of metallothioneins and their interactions with various N-donor ligands encountered in nature.     

An unusual ligand in copper chemistry: coordination oligomers and polymers containing the [[CpMo(CO)2]2(mu,eta2-Sb2)] cluster

The coordination behavior of [[CpMo(CO)(2)}(2)(mu,eta(2)-Sb(2))] (1; Cp = cyclopentadiene) toward Cu(I) was investigated. Its reaction with CuX (X = Br, Cl, and I) produced oligomers or polymers of the general formula [[CpMo(CO)(2)](2)(mu,eta(2)-Sb(2))(mu-CuX)](n). While 2 (X = Cl, n = 2) and 3 (X = Br, n = 2) proved to be halogen-bridged dimers in both solution and solid state, the molecules of 4 (X = I, n = infinity) self-assembled in the crystal forming a linear polymer with a Cu-I skeleton supported by Sb-Cu bonds. The reaction of 1 with Cu[GaCl(4)] resulted in the formation of the ionic complex [[CpMo(CO)(2)](2)(mu,eta(2)-Sb(2))](4)Cu(2)[GaCl(4)](2) (5). Its dication contains four [[CpMo(CO)(2)](2)(mu,eta(2)-Sb(2))] ligands arranged around a Cu-Cu dumbbell. All new compounds were characterized using IR, electrospray ionization mass spectrometry, (1)H NMR, elemental analysis, and single-crystal X-ray diffraction. The ligand was oxidized by both silver(I) and copper(II), and a cyclovoltammetric study revealed that 1 suffered irreversible reduction and oxidation in a dichloromethane solution at -2.04 and 0.10 V, respectively, versus ferrocene.     

A series of vanadogermanates from 1D chain to 3D framework built by Ge-V-O clusters and transition-metal-complex bridges

Three novel extended vanadogermanates, {[(en)(2)Cd(2)Ge(8)V(12)O(40)(OH)(8)(H(2)O)][Cd(en)(2)](2)}·6H(2)O (1), {[Zn(2)(dap)(3)][Zn(dap)](2)Ge(6)V(15)O(48)(H(2)O)}[Zn(dap)(2)(H(2)O)](2)·3H(2)O (2), and {[Cd(3)(μ-dien)(2)(Hdien)(2)(H(2)O)(2)]Ge(4)V(16)O(42)(OH)(4)(H(2)O)}·2H(2)O (3; en=ethylenediamine, dap=1,2-diaminopropane, dien=diethylenetriamine), have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy, powder XRD, thermogravimetric analysis, and single-crystal XRD. Their Ge-V-O cluster anions are derived from the V(18)O(42) cluster shell by replacing VO(5) square pyramids with Ge(2)O(7) groups. Compound 1 exhibits a 1D sinusoidal chain built up from rare inorganic-organic hybrid dicadmium-substituted vanadogermanate {[Cd(en)](2)V(12)O(40)(GeOH)(8)(H(2)O)} clusters and [Cd(en)(2)] complexes. Compound 2 is the first example of a 2D network based on linkage of the unusual {Ge(6)V(15)O(48)(H(2)O)} clusters and two types of Zn complex fragments. Compound 3 is an unprecedented 3D framework built by {Ge(4)V(16)O(42)(OH)(4)(H(2)O)} clusters and rare trinuclear bridging complex cations [Cd(3)(μ-dien)(2)(Hdien)(2)(H(2)O)(2)](8+). Magnetic measurements illustrate that both 1 and 2 have antiferromagnetic exchange interactions between metal centers, whereas 3 exhibits ferrimagnetic behavior, which is rare in polyoxovanadate complexes.     

Polymeric zinc ferrocenyl sulfonate as a molecular aspirator for the removal of toxic metal ions

A porous bilayered open coordination polymer [Zn(4,4'-bpy)(2)(FcphSO(3))(2)](n) (1; FcphSO(3)Na=m-ferrocenyl benzenesulfonate), has been assembled from Zn(NO(3))(2), m-ferrocenyl benzenesulfonate, and the bridging ligand 4,4'-bipyridine (4,4'-bpy). Ion-exchange induced products [Cd(0.6)Zn(0.4)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (2), [Zn(0.75)Pb(0.25)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (3), and [Cu(0.5)Zn(0.5)(4,4'-bpy)(2)(FcphSO(3))(2)](n) (4) could be obtained directly by suspending a big single crystal of 1 into concentrated solutions of Cd(NO(3))(2), Pb(NO(3))(2), and Cu(NO(3))(2), respectively. Most importantly, the big single crystal of 1 could be partly regenerated after immersion into concentrated aqueous solutions of Zn(NO(3))(2). On the other hand, powdered 1 could also be used as a metal ion adsorbent because of the well-defined pore size and pore shape. Ion exchange takes place along with the process of ion sorption. The big single crystal of 1 removes harmful metal ions by means of ion exchange, whereas powdered 1 removes toxic metal ions mainly through ion sorption. Also, compound 1 could be employed as a multi-ion analysis fluorescent probe to detect dangerous metal ions, such as Pb(2+), Cd(2+), Ag(+), and Cu(2+). The compounds described in this study may have potential applications in the design of new molecular devices.