A series of metal-organic frameworks constructed with 2,2′-bipyridine-3,3′-dicarboxylate: Syntheses, structures, and physical properties

To determine the influence of metal ion and the auxiliary ligand on the formation of metal-organic frameworks, six new coordination polymers, {[Mn₂(bpdc)(bpy)₃(H₂O)₂] · 2ClO₄ · H₂O}_n (1), {[Mn(bpdc)(dpe)] · CH₃OH · 2H₂O}_n (2), {[Cu(bpdc)(H₂O)₂]}_n (3), {[Zn(bpdc)(H₂O)₂]}_n (4), {[Cd(bpdc)(H₂O)₃] · 2H₂O}_n (5), and {[Co(bpdc)(H₂O)₃] · 0.5dpe · H₂O}_n (6) (H₂bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique Mn^II ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc²⁻ ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied.     

Metal-organic open frameworks with one-dimension channels assembled with pyridine 2,6-dicarboxylic acid and N-containing auxiliary ligands: Syntheses, crystal structures, and physical characterization

Four new complexes, {[Mn(imH)₂(pdc)]·H₂O}_n (1), [Zn₂(pdc)₂(H₂O)₅]·2H₂O (2), [Zn(imH)₂(pdc)]·H₂O (3), {[Zn₂(pdc)₂(bpy)(H₂O)₂]·5H₂O}_n (4) [imH = imidazole pdc = pyridine 2,6-dicarboxylate, bpy = 4,4′-bipyridine] have been synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR, PXRD, single-crystal X-ray diffraction and thermogravimetric analyses. All the four complexes display a three-dimensional (3D) open framework with one-dimensional (1D) channels that are filled with lattice water molecules. Particularly, in 4, the lattice water molecules form an infinite water chain. Both 1 and 4 consist of 1D polymeric chains. While 2 contains a dinuclear Zn(II) unit, and 3 is a mononuclear complex. Further, the result of thermal analysis of 1 and 2 shows the robustness of the overall supramolecular three-dimensional architecture. Complexes 1, 3, and 4 exhibit strong fluorescent emissions in the solid state at room temperature and could be significant in the field of photoactive materials.     

Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H₂O)] · 2H₂O (H₃Sas = N-(2-hydroxybenzyl)-l-aspartic acid) (1), [Cu(HMeSglu)(H₂O)] · 2H₂O (H₃MeSglu = (N-(2-hydroxy-5-methylbenzyl)-l-glutamic acid) (2), [Cu₂(Smet)₂] (H₂Smet = (N-(2-hydroxybenzyl)-l-methionine) (3), [Ni(HSas)(H₂O)] (4), [Ni₂(Smet)₂(H₂O)₂] (5), and [Ni(HSapg)₂] (H₂Sapg = (N-(2-hydroxybenzyl)-l-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6.     

Carboxyester hydrolysis promoted by Cu(II) complexes of pyridyl-amine carboxylate-pendant ligands

Multidentate ligands containing tripodal pyridyl-amine moieties tethered to a carboxylate group by alkyl linkers of varying lengths were synthesized to obtain a series of water-soluble ligands to elucidate the effects of the differing coordination environments on the properties of the resulting metal complexes. These new, water-soluble ligands, [bis-(2-pyridin-2-yl-ethyl)-amino]-acetic acid (L¹), 3-[bis-(2-pyridin-2-yl-ethyl)-amino]-propionic acid (L²), 4-[bis-(2-pyridin-2-yl-ethyl)-amino]-butyric acid (L³), and 6-[bis-(2-pyridin-2-yl-ethyl)-amino]-hexanoic acid (L⁴), were treated with copper(II) perchlorate hexahydrate to yield the corresponding Cu(II) complexes, which have all been characterized by X-ray crystallography. L¹ binds Cu(II) to form the tetrameric complex {[Cu(μ-¹)][ClO₄] · 4H₂O}₄ (1) in the solid state, whereas the Cu(II) complexes of ligands L²-L⁴ form long-chain one-dimensional polymeric complexes {[Cu(μ-L²)][ClO₄] · H₂O}_n (2), {[Cu(μ-L³)][ClO₄] · H₂O}_n (3), and {[Cu(μ-L²)][ClO₄]  · H₂O}_n (4), respectively, in the solid state. Complexes 1-4 dissolved in 10% (v/v) CH₃CN aqueous solution were tested for their ability to promote the hydrolysis of the activated ester compound 4-nitrophenylacetate (NA), with 3 being the most active complex and 1 being the least active, possibly due to differences in the ability of the carboxylate moiety to act as either a general base or a nucleophile in the hydrolysis of NA as dictated by the tether length. The pK_a values of the copper-bound aquo ligands in solution were measured by spectrophotometric titration.     

Two forms of a copper(II) complex of 3-phenyl-5-(2-pyridyl)-4-(4-pyridyl)-4H-1,2,4-triazole: a six-coordinate monomer versus a five-coordinate polymer

The reaction of the new bidirectional ligand 3-phenyl-5-(2-pyridyl)-4-(4-pyridyl)-4H-1,2,4-triazole (pyppt) with Cu(ClO₄)₂ · 6H₂O in a 2:1 molar ratio in EtOH affords the complex [Cu^II(pyppt)₂(ClO₄)₂] · H₂O (1) as a microcrystalline turquoise solid. Recrystallisation of complex 1 from MeCN by vapour diffusion of Et₂O gives blue crystals of the monomeric octahedral complex [Cu^II(pyppt)₂(ClO₄)₂] · MeCN (2). In contrast, addition of EtOH to a solution of complex 1 in MeCN followed by slow evaporation yields blue crystals of the five-coordinate polymeric complex {[Cu^II(pyppt)₂](ClO₄)₂ · EtOH}_∞ (3). The structures of both complexes have been determined by single crystal X-ray diffraction.     

Metal-regulated assemblies of Cu, Ni, and Zn complexes with isoquinoline-3-carboxylate displaying diverse supramolecular networks

Three distinct coordination complexes, viz. {[Cu(μ-L)₂] · (H₂O)₄}_n (1), [Ni(L)₂(CH₃OH)₂] (2), and [Zn(L)₂(H₂O)₂] · (H₂O)₂ (3), have been prepared by the reactions of metal nitrates with isoquinoline-3-carboxylic acid (HL). X-ray single-crystal diffraction suggests that 1 is a 1D chain coordination polymer in which the Cu^II ions are connected by carboxylates, whereas complexes 2 and 3 represent discrete mononuclear species. In all the cases, the coordination entities are further organized via hydrogen-bonding interactions to generate multifarious supramolecular networks. Remarkably, a well-resolved 1D water morphology is observed for the first time in the crystalline lattice of 1 along [1 0 0], which consists of edge-sharing tetrameric subunits and stabilized by the metal-organic host surroundings.     

Binuclear copper and zinc complexes based on polypyridyl ligand 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz): Synthesis, spectral and structural characterization

The reaction of MCl₂ · 2H₂O (M = Cu, Zn) with 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz) (referred hereafter as L) in 2:1 molar ratio in acetonitrile at room temperature afforded binuclear complexes [M₂(κ³-L)Cl₄] [Cu (1), Zn (2)] where the ligand is bis-tridentate manner. The complexes have been characterized by elemental analyses, FAB-MS, IR, EPR, NMR and electronic spectral studies. Solid state structures of both the [Cu₂(κ³-L)Cl₄] · 5H₂O (1), [Zn₂(κ³-L)Cl₄] · H₂O (2) have been determined by single crystal X-ray analyses. A well-resolved uudd cyclic water tetramer and water monomer were reported in the crystal host of [Cu₂(κ³-L)Cl₄] · 5H₂O (1) and [Zn₂(κ³-L)Cl₄] · H₂O (2) showing the contribution of the water cluster to the stability of the crystal host 1 and 2.     

N,N′-Bis(3-methoxysalicylidene)propane-1,2-diamine mononuclear 4f and heterodinuclear Cu-4f complexes: Synthesis, crystal structure and electrochemical properties

Reactions of H₂L [H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine] and Ln(NO₃)₃ · 6H₂O give rise to two different mononuclear 4f complexes, namely, {[(H₂L)La(NO₃)₃(MeOH)] · H₂O}_n (1) and [(H₂L)Nd(NO₃)₃] (2). Further additions of Cu(Ac)₂ · H₂O to the mononuclear 4f complexes yield expected heterodinuclear Cu-4f complexes [LCu(Me₂CO)Ln(NO₃)₃] (3, Ln = Nd; 4, Ln = Eu; 5, Ln = Dy). Complex 1 is a unique 1D polymeric chain structure, and 2 is one of the few structurally characterized discrete hexadentate salen-type mononuclear 4f complexes. Complexes 3-5 are similar to their analogues. However, they are prepared by a reversed synthetic route in contrast to their isomorphic complexes. Electrochemical behavior of heterodinuclear Cu-4f complexes 3-5 has been examined by cyclic voltammetry in acetonitrile. The redox potential of heterodinuclear Cu-4f complexes 3-5 shows significant anodic shift comparing to that of mononuclear copper complex (LCu). A tendency of anodic shift was observed in a sequence of 3 < 4 < 5. This results from the modulating effect of coordination geometry around Cu(II) ion on redox potential.     

Zinc(II) and copper(II) 1D coordination polymeric complexes of a reduced Schiff base ligand

The reaction of Zn(ClO₄)₂ · 6H₂O and Cu(ClO₄)₂ · 6H₂O with H₃Sas (H₃Sas = N-(2-hydroxybenzyl)-L-aspartic acid in water afforded the complexes [Zn₆(Sas)₄(H₂O)₈]·5H₂O (1) and [Cu(HSas)(H₂O)] (2), respectively, which were characterized by infrared spectroscopy, elemental analysis, thermogravimetry and single-crystal X-ray crystallography. In 1, the pentanuclear clusters formed by four H₃Sas ligands and five Zn(II) metal ions are bridged by the “[Zn(H₂O)₄]²⁺” cations to form 1D polymeric chains. While in 2, the mononuclear [Cu(HSas)(H₂O)] repeating units form a 1D zigzag chain and further extended by strong intermolecular hydrogen bonds to form a 2D sheet. The different coordination geometries of Cu(II) and Zn(II) show significant influence on the polymeric structures.     

Crystal structure, thermal stability and theoretical investigation on four 1,3-bis(1,2,4-triazol-1-yl)propane-based copper(II) complexes

Self-assembly of flexible 1,3-bis(1,2,4-triazol-1-yl)propane (btp), inorganic Cu(II) salt and rigid benzene-based carboxylate coligand generates four complexes, {[Cu(btp)₂(CH₃OH)(H₂O)]·H₂O·2ClO₄}_n (1), {[Cu(btp)(Hbtc)₂]·0.5H₂O}_n (2), [Cu(btp)₂(H₃btea)₂]_n (3), and [Cu(btp)(nb)₂] (4) (H₃btc = 1,3,5-benzenetricarboxylic acid, H₄btea = 1,2,4,5-benzenetetracarboxylic acid, Hnb = p-nitrobenzoic acid), which are fully structural characterized by single-crystal X-ray crystallography, elemental analysis, IR, and TG-DTA techniques. Structural determinations reveal that the polymeric two-dimensional (2D) Cu-btp grid-like layer for 1, 1D linear single- and double-stranded chains for 2 and 3, as well as the discrete binuclear structure for 4, are jointly directed by the coordination polyhedrons of the Cu(II) ion and the exo-bidentate bridging btp core ligand with various conformations. The theoretical calculations suggest that the trans-trans btp is the most stable conformation, and the metal binding site is collectively determined by the electron density of N donors and the spatial orientation of the btp ligand. Unexpectedly, the polycarboxylate anions in 1-4 can only act as terminal coligands not popular bridging connectors. The thermal stability of the resulting complexes is also compared.     

Conversion of 2-(aminomethyl) substituted pyridine and quinoline to their dicarbonyldiimides using copper(II) acetate

In air, hydrated ethanolic (95%) solution of 2-(aminomethyl) substituted pyridine and quinoline, on stirring with half equivalent of Cu(OAc)₂·H₂O, respectively afforded [Cu(bpca)(OAc)(H₂O)]·H₂O (1) and [Cu(bqca)(OAc)(H₂O)] (2) {bpca = bis(2-pyridylcarbonyl)diimide ion and bqca = bis(2-quinolylcarbonyl)diimide ion} in good yields. These reactions involve oxidation of the methylene group and formation of the bond between nitrogen and carbon in N-C(O) through coupling. The complex [Cu(pqca)(OAc)(H₂O)]₃[Cu₂(OAc)₄(EtOH)₂]_1.5 (3) {pqca = (2-pyridylcarbonyl)(2-quinolylcarbonyl)diimide ion} was synthesized by stirring an ethanolic solution of the Schiff base [(2-pyridyl)-N-((2-quinolyl)methylene)methanamine] (L1) and with one equivalent of Cu(OAc)₂·H₂O. A plausible mechanism for the conversion has been proposed. The free ligands were isolated as crystalline solids from compounds 1-3, by extrusion of Cu²⁺ ion using EDTA²⁻. The molecular structures of 1-3 and bqcaH were established by X-ray crystallography and compounds having quinolyl group have π-stacking interactions.     

Synthesis, crystal structure and luminescent behaviour of coordination complexes of copper with bi- and tridentate amines and phosphonic acids

The synthesis and crystal structure of four new copper(I) and copper(II) supramolecular amine, and amine phosphonate, complexes is reported. Reaction of copper(I) with 2-,9-dimethyl-1-10-phenanthroline (dmp) produced a stable 4-coordinate Cu(I) species, [Cu^(I)(dmp)₂]Cl · MeOH · 5H₂O (2), i.e., the increased steric hindrance in the ‘bite’ area of dmp did not prevent interaction with the metal and provided protection against oxidation which was not possible for the phen analogue [R. Clarke, K. Latham, C. Rix, M. Hobday, J. White, CrystEngCommun. 7(3) (2005), 28-36]. Subsequent addition of phenylphosphonic acid to (2) produced two structures from alternative synthetic routes. An ‘in situ’ process yielded red block Cu(I) crystals, [Cu^(I)(dmp)₂] · [C₆H₅PO₃H₂ · C₆H₅PO₃H] (4), whilst recrystallisation of (2) prior to addition of the acid (‘stepwise’ process) produced a green, needle-like Cu(II) complex, [Cu^(II)(dmp) · (H₂O)₂ · C₆H₅PO₂(OH)] [C₆H₅PO₂(OH)] (3). However, addition of excess dmp during the ‘stepwise’ process forced the equilibrium towards product (4) and resulted in an optimum yield (99%). The structure of (4) was similar to the phen analogue, [Cu^(II)Cl(phen)₂] · [C₆H₅PO₂(OH) · C₆H₅PO(OH)₂] (1) [R. Clarke, K. Latham, C. Rix, M. Hobday, J. White, CrystEngCommun. 7(3) (2005), 28-36], but the presence of dmp exerted some influence on global packing, whilst (3) exists as a polymeric layered material. In contrast, reaction of copper(I) with di-2-pyridyl ketone (dpk), followed by phenylphosphonic acid produced purple/blue Cu(II) species, [Cu^(II)(dpk · H₂O)₂] Cl₂ · 4H₂O (5), and [Cu^(II)(dpk · H₂O)₂] · [C₆H₅PO₂(OH)₂ · C₆H₅PO(OH)₂] (6), respectively, i.e., in both cases oxidation of copper occurred. Solid-state luminescence was observed in (2) and (4). The latter showing a 5-fold enhancement in intensity.     

Hydrogen-bonding assemblies constructed from metalloligand building blocks and H2O

New hydrogen-bonding assemblies were synthesized from the reaction of a metalloligand, [Cu(2,4-pydca)₂]²⁻ (L^Cu) (2,4-pydca = 2,4-pyridinedicarboxylate), with a Fe^II ion or an imidazole in an aqueous medium and crystallographically characterized. The obtained compounds, [Fe(H₂O)₆][Cu(2,4-pydca)₂] (1) and [Cu(2,4-pydca)(imidazole)₂] · 2H₂O (2), have metalloligand dimer units, [Cu₂(2,4-pydca)₄]⁴⁻ and [Cu₂(2,4-pydca)₂(imidazole)₄], respectively, each of which assembles by π-π (1) and hydrogen-bonding (2) interactions to form 1-D metalloligand arrays. The 1-D metalloligand arrays are linked by rich hydrogen-bonding interactions via H₂O molecules.     

Solvothermal syntheses and structural characterization of a series of metal-hydroxycarboxylate coordination polymers

The combination of transition metal ions with mixed ligands resulted in the formation of three new coordination polymers, {[Co(C₄H₄O₅)(bpe)(H₂O)₂] · (0.5bpe)(H₂O)}_n (1), {[Cu(C₄H₄O₆)(bipy)] · 5H₂O}_n (2) and {[Cu(C₄H₄O₅)(bpa)] · 2.5H₂O}_n (3) (, , bpe = 1,2-bis(4-pyridyl)ethene, bipy = 2,2′-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane), which were prepared under solvothermal conditions and characterized by single-crystal X-ray diffraction. 1 and 2 feature 1D chain structures. Interestingly, each pair of chains recognizes each other through aromatic π-π stacking interactions, generating a zipper-like double-stranded chain in 2. Compound 3 shows 2D 6³ topology framework with a rectangle-like grid.     

Construction of one-, two- and three-dimensional Cu(I) polymeric architectures containing bis(diphenylphosphino)acetylene and 4,4′-bipyridine linking ligands

One-dimensional {[Cu₂(dppa)₂(4,4′-bipy)(CH₃CN)₂](BF₄)₂ · 2CH₃CN}_n (1), two-dimensional {[Cu₂(dppa)(4,4′-bipy)₂(CH₃CN)₂](BF₄)₂ · 4CH₂Cl₂ · 4H₂O}_n (2) and three-dimensional {[Cu₂(dppa)(4,4′-bipy)₃](BF₄)₂ · 2CH₂Cl₂ · 3CH₃CN · 3H₂O}_n (3) polymeric complexes have been prepared by self-assembly of [Cu(MeCN)₄]BF₄, Ph₂PCCPPh₂ (dppa) and 4,4′-bipyridine (4,4′-bipy) in a 2:2:1, 1:1:1 and 2:2:3 molar ratio, respectively. The structures of 1-3, determined by an X-ray diffraction study, reveal a linear spring-like architecture for 1, a planar honeycomb grid for 2 and an interlocked adamantoid network for 3.     

Syntheses, structures, and magnetic properties of 3d-4f heterometallic complexes constructed from pyrazole-bridged CuLn dinuclear units

A series of pyrazole-bridged heterometallic 3d-4f complexes, [CuDy(ipdc)₂(H₂O)₄] · (2H₂O)(H₃O⁺) (1) and [CuLn(pdc)(ipdc)(H₂O)₄] · H₃O⁺ (Ln = Ho (2), Er (3), Yb (4); H₃ipdc = 4-iodo-3,5-pyrazoledicarboxylic acid; H₃pdc = 3,5-pyrazoledicarboxylic acid), {[Cu₃Ln₄(ipdc)₆(H₂O)₁₆] · xH₂O}_n (Ln = Sm (5), x = 8.5; Ln = Eu (6), x = 7; Ln = Gd (7), Tb (8), x = 9), have been synthesized and structurally characterized. Ligand H₃ipdc was in situ obtained by iodination of ligand H₃pdc. Complexes 1-4 are pyrazole-bridged heterometallic dinuclear complexes, and 2-4 are isostructural. Complexes 5-8 are isostructural and comprised of an unusual infinite one-dimensional tape-like chain based on pyrazole-bridged heterometallic dinuclear units. The magnetic properties of compounds 1-4, 7 and 8 have been investigated through the magnetic measurement over the temperature range of 1.8-300 K.     

Hydrothermal synthesis, crystal structures and properties of new Fe, Co, Ni, and Zn complexes with 6-quinolinecarboxylate: Interplay of coordinative and noncovalent interactions

Reactions of Fe^II, Co^II, Ni^II, and Zn^II salts with 6-quinolinecarboxylic acid (HL) under the hydrothermal conditions afford three monomeric complexes [M(L)₂(H₂O)₄] (M = Fe^II for 1, Co^II for 2, and Ni^II for 3) and a 1-D polymeric species {[Zn(L)₂(H₂O)] · H₂O}_n (4). The crystal structures of the ligand HL and these four complexes have been determined by using the X-ray single-crystal diffraction technique. The results suggest that complexes 1-3 are isostructural, displaying novel 3-D pillar-layered networks through multiple intermolecular hydrogen bonds, whereas in coordination polymer 4, the 1-D comb-like coordination chains are extended to generate a hydrogen-bonded layer, which is further reinforced via aromatic stacking interactions. Solid-state properties such as thermal stability and fluorescence emission of the polymeric Zn^II complex 4 have also been investigated.     

Influence of coanions on construction of copper(II)/4,4′-dipyridyl sulfide(dps) coordination polymers

The influence of coanion on self-assembly of CuSO₄ and 4,4′-dipyridyl sulfide (dps) was studied in this paper. During the formation of Cu(II)/dps coordination polymers, coanions Cl⁻, SCN⁻ and were added in the solution respectively. Three novel coordination polymers were obtained, {[Cu(dps)₂ · (SO₄)₂][Cu(dps) · Cl · (H₂O)₂]₂ · 12H₂O}_n (1 · 12H₂O, a 3D network), {[Cu(SCN)₂(dps)(CH₃OH)₂][Cu(dps)₂ · SO₄][Cu(dps)(CH₃CH₂OH)₂ · SO₄] · 5H₂O}_n (2 · 5H₂O, a 3D network), and {[Cu(dps)₂(H₂O)₂] · (PF₆)₂ · 3H₂O}_n (3 · 3H₂O, a 2D lattice network). Different coanion shows different influence on framework construction. In 1 and 2, Cl⁻ and SCN⁻ act as terminal ligands and similar 3D frameworks were composed of [Cu(dps)] layer with larger cavity (ca. 400 Å) and sulfate bridge; in 3, replaces entirely and the 3D framework was broken due to the removal of bridging anions. However, a 2D [Cu(dps)]₄ undulating grid was preserved in 3.     

Potential tridentate salicylaldehyde hydrazone of arylalkanoic acid coordinate to copper(II) acting as dinegative tetradentate ligands

A chiral Schiff base N-(S)-2-(6-methoxylnaphthyl)-propanoyl-N′-(2-hydroxylbenzylidene)hydrazine (H₂L) has been synthesized. Reaction of H₂L with Cu(OAc)₂ · H₂O led to the formation of a metal complex {[CuL] · H₂O · 2DMF}_∞ (1). In complex 1, the potential dinegative tridentate L²⁻ ligand acting as tetradentate bridging ligand coordinate to two metal ions so as to form a novel infinite metal-organic coordination chain structure. The enantiomerically pure ligand H₂L presents two different sets of signals in the ¹H NMR spectrum either in chloroform solution or in dimethylsulfoxide solution, showing the presence of both (E) and (Z) isomers. The X-ray structural investigations of H₂L revealed that it is the fully extended E-configuration in the solid state.     

Syntheses and characterization of two metal-water clusters

Complexes 1 and 2, formulated {[Co₂(4,4′-bpy)₂ · 8H₂O] · (CCA)₂ · 4H₂O}_n (1) and {[Co(TMG)(4,4′-bpy)(H₂O)₂] · 3H₂O}_n (2) (H₂CCA = 2-carboxylatocinnamate, H₂TMG = 3,3-tetramethyleneglutate, 4,4′-bpy = 4,4′-bpyridine) have been synthesized by the reaction of cobalt (II), 4,4′-bpy and carboxylate ligands, in which 2D metal-water layers and 1D metal-water chains have been observed, respectively. In the metal-water clusters, the water molecules are trapped by the cooperative association of coordination interactions as well as hydrogen bonds.