Isomorphous Coordination Polymers Research Articles

Five new isomorphic coordination polymers with large conjugated ligands: Synthesis, crystal structures and performances

Five new coordination compounds with isomorphic frameworks, {[M(cpp)2(H2O)2]·3H2O}n [M ​= ​Co (1), Cd (2), Mn (3), Ni (4), Zn (5)], were successfully synthesized through the reactions of 1-(4-carboxyphenyl)-3-(pyrazin-2-yl)pyrazole (Hcpp) and a series of transition metal salts under the solvo-thermal conditions. Compounds 1–5 were characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, infrared spectra and thermogravimetric analysis. Isomorphic compounds 1–5 display an abnormal two-dimensional helical layer containing a M4(cpp)4 cavity with the dimension of 26.21 ​× ​8.39 ​Å2. Variable-temperature magnetic susceptibility measurements indicate weak antiferromagnetic interactions with Curie constant (2.08 ​cm3 ​K ​mol−1) and Weiss constant (−6.90 ​K) in compound 1. Compounds 2 and 5 show apparently blue light emission, wherein the sensing responses to small molecules, inorganic anions and metal cations indicate compound 5 can be used as a multifunctional fluorescence probe to detect aniline, Fe3+, CrO42− and Cr2O72− through fluorescence quenching and the corresponding quenching mechanisms are proposed.

Post-synthetic modification of Isomorphic coordination polymers with metal ion exchange and catalytic cycloaddition of CO2

A coordination polymeric crystal 1 was successfully synthesized from H4L (5,5′-(1,4-phenylenebis (methoxy))diisophthalic acid), bidpe (4,4′-bis(lmidazolyl)diphenyl ether), and Zn(NO3)2·6H2O under solvothermal conditions, and characterized by single-crystal X-ray diffraction. Then, two new crystals 1Fe and 1Cu were obtained with metal ion exchange when 1 was dipped into the DMF solution for FeCl2 and CuCl2, respectively. The exchange process demonstrated that the high valence metal ion with strong acidity could be destroyed the structure of the crystals. Therefore, it should be exchanged with lower valence ion and then oxidized to the high valence state, which could be a feasible way to obtain the crystals with high valence metal ions. Further, the magnetic property and the synergistic CO2 conversion with epoxide for 1Fe and 1Cu were also investigated, and the results shown that 1Fe could be regarded as a potential catalyst for this conversion.

2D/3D coordination polymers based on di-, tri-, tetranuclear and polymeric chain units with a tricarboxylate ligand: Structures, magnetic and luminescent properties

Six novel coordination polymers (CPs), [M2(HL)2(4,4′-bipy)(H2O)2] (M = Co, for 1; Ni, for 2), [M3(L)2(CH3CN)2(H2O)2]·2H2O (M = Co, for 3; Ni, for 4), [Co4(OH)2(L)2(4,4′-bipy)(H2O)4]·2H2O (5) and [Zn4(OH)2(L)2(DMA)2(H2O)2] (6) have been synthesized by using different metal ions and 5-(2-nitro-4-carboxylphenyl)isophthalic acid (H3L) ligand in the absence/presence of 4,4′-bipyridine (4,4′-bipy) ancillary ligand. Interestingly, these CPs exhibit different structures based on di-, tri-, tetranuclear and chain units, respectively. CPs 1 and 2 are isomorphous and possess a (4,4) 2D layer in which dinuclear [M2(µ2-Ocarboxylate)2]2+ clusters are interlinked by the HL and 4,4′-bipy ligands. In isomorphous CPs 3 and 4, the linear trinuclear [M3(μ2-COO)2(μ2-Ocarboxylate)]3+ clusters are linked by the L ligands to give a 2D layer with a (3,6)-connected kgd topology. In 5, the chair-shaped tetranuclear [Co4(μ3-OH)2]6+ clusters are interlinked by organic spacers into a 2D layer with a (3,8)-connected net with point symbol (3·42)2(34·46·56·68·73·8). Compared with 5, the cluster structures of 5 and 6 are very similar, but in 6, the chair-shaped tetranuclear [Zn4(μ3-OH)2]6+ clusters are connected by the double (μ2-syn, anti-COO)2 bridges to form a 1D chain. The chains further are cross-linked by the L ligands to build a 3D framework. Magnetic analyses suggest that all of the short bridging moieties in 1–5 transmit antiferromagnetic couplings between metal(II) ions. Moreover, CP 6 shows an intense solid-state emission at room temperature. This work opens up the use of this tricarboxylate ligand for generating CPs with interesting structures and functional properties.

Crystal structures and magnetic properties of two isomorphic nickel(II) and cobalt(II) coordination polymers-based nitrogen-heterocyclic tricarbolylate ligands

5-(3,4-Dicarboxylphenyl) picolinic acid (H3dppa) was applied as a new building block for the synthesis of two isomorphic coordination polymers, namely [Ni1.5dppa(H2O)3]n·nH2O (1), [Co1.5dppa(H2O)3]n·nH2O (2). Two compounds were generated by a hydrothermal self-assembly method using the corresponding metal(II) acetates and H3cppa ligand. Structure analysis reveals that compounds 1 and 2 are isomorphic both featuring a two-dimensional wave structure and are finally extended into the three-dimensional supramolecular architecture though hydrogen bonding interactions. Magnetic susceptibility measurements indicate that domain a weak ferromagnetic exchange coupling between the adjacent Ni(II) centers in 1, and a weak antiferromagnetic coupling between Co(II) ions in for 2.

Two Isomorphic Coordination Polymers Based on Triazolyl Derivative and Dicarboxylate Ligand: Synthesis, Structures, and Properties

Two new isomorphic inorganic-organic hybrid 2D extended networks of Mn(II)/Co(II) with the general molecular formula [M(H2L)(ip)]n·4nH2O, where Mn(II) (1), Co(II) (2), H2L = 3-(1H-pyrazol-4-yl)-5-(pyridin-4-yl)-1,2,4-triazole, H2ip = 1,3-benzenedicarboxylic acid, have been synthesized and characterized by single-crystal X-ray diffraction and magnetic measurements. They crystallize in the triclinic system, space group P-1, display the same box-like bilayer motif of (4, 4) net, and are finally extended into the three-dimensional supramolecular structure via hydrogen bonding interactions. The compound 1 is characterized by antiferromagnetic fitting data based on a dimeric Mn(II) model with negligible magnetic transmission through the carbon skeleton of ip2– and H2L pathway. Thermal analysis of compound 1 has also been studied.

Comprehensively Understanding Isomorphism and Photoluminescent Nature of Two-Dimensional Coordination Polymers of Cd(II) and Mn(II) with 1,1'-Ethynebenzene-3,3',5,5'-tetracarboxylic Ligand.

Four isomorphic two-dimensional (2D) homo- and heterometallic coordination polymers (CPs), [(Cd xMn1- x)3(HEBTC)2(DMSO)6] with x = 1 (1), 1/3 (2), 0.5 (3), and 2/3 (4) were prepared by conventional one-pot self-assembly approach, using Cd2+ or mixtures of Cd2+ and Mn2+ with 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylic (H4EBTC) under solvothermal conditions. The crystal structures of four isomorphic CPs are composed of center-symmetric trinuclear metal clusters building units linked by HEBTC3- ligands, extending into (3, 6)-connected topological 2D nets. Four CPs are isomorphic to the Mn-CP, [Mn3(HEBTC)2(DMSO)6], we recently reported. The solid-state photoluminescence of 1-4 shows dual emissions at ambient condition, where the emission bands centered at ca. 390 and 562 nm in 1 are assigned to the fluorescence and phosphorescence within HEBTC3- ligand, respectively; however, the emission bands centered at around 397 and 470 nm in 2-4 are attributed to fluorescence, corresponding to electron transition within HEBTC3- ligand and MLCT transition between HEBTC3- ligand and Mn2+ ion. In addition, the origin of isomorphism between 1 and Mn-CP is also discussed.

Four 3D coordination polymers based on layers with single syn-anti carboxylate bridges: synthesis, structures, and magnetic properties.

Four novel coordination polymers (CPs) based on a new 4-(3,5-dicarboxylphenyl) picolinic acid ligands (H3L), [M3(L)2(H2O)6]·4H2O (M3 = Mn3, 1; Co3, 2; Ni3, 3, Co1.01Ni1.99, 4), have been hydrothermally synthesized, and structurally and magnetically characterized. In these isomorphous CPs, octahedrally coordinated metal ions are linked by the single syn–anti carboxylate bridge (μ-COO) to give linear trinuclear motifs. The motifs are connected through the other single syn–anti carboxylate bridge (μ-COO) to give a 2D (4,4) layer, and the layers are interlinked by the L ligands into 3D frameworks. Magnetic measurement indicates that antiferromagnetic interactions between metal ions are mediated through the single syn–anti carboxylate bridges in 1 and 2, while the same carboxylate bridges in 3 transmit ferromagnetic couplings. The bimetallic CP 4 shows interesting complicated magnetic behaviors due to the competition effect of Co(ii) and Ni(ii) ions.

Synthesis, structural characterization and computational studies of layered metal phosphonates: [M(HO3P–C5H4N–PO3H)2(H2O)2]n[MII= Co, Zn, Cd

Three novel isomorphous coordination polymers with a general formula [M(HO3P–C5H4N–PO3H)2(H2O)2]n [MII = Co (1), Zn (2) and Cd (3)] have been synthesized and characterized by powder and single-crystal X-ray diffraction, vibrational spectroscopy (IR and Raman) and simultaneous thermal analysis (TG-DTA-MS). Crystal structure analyses of compounds 1–3 have revealed that both phosphonate groups of (pyridin-1-ium-3,5-diyl)diphosphonate ligands serve to extend the metal cations into a strongly undulated grid structure parallel to the (101) plane. The adjacent monolayers are held together via multiple hydrogen bonds and offset face-to-face π–π interactions. The interlayer interaction energy values, estimated using the CRYSTAL code, have revealed that the stabilization energies of compounds 1–3 are quite similar, where 1 is least and 3 most advantageous. Computational studies have been further related to the results of thermal analyses. In the case of compound 1, which has unpaired electrons at the metal centre, the investigation has been supplemented by magnetic measurements. The magnetic properties of 1 (1.7–300 K) have been analyzed assuming that any possible exchange interactions are very weak. The obtained best-fit parameters are: Δ (axial splitting of 4T1g term) = −478 cm−1, λ (spin–orbit coupling) = −103 cm−1, α (orbital reduction factor) = 1.38, and zJ′ (mean-field exchange parameter) = −0.11 cm−1. The negative value of Δ implies that the ground state is the orbital doublet, which cannot be treated within the spin-Hamiltonian approach.

Magnetic coupling and slow relaxation of magnetization in chain-based Mn(II), Co(II), and Ni(II) coordination frameworks.

Three isomorphous coordination polymers based on the chain with triple (μ-1,1-N3)(μ-1,3-COO)2 bridges have been synthesized from a new zwitterionic dicarboxylate ligand [L(-) = 1-(4-carboxylatobenzyl)pyridinium-4-carboxylate]. They are of formula [M(L)(N3)]n·3nH2O [M = Mn(II), Co(II), and Ni(II)]. In these compounds, the mixed-bridge chains are linked into 2D coordination networks by the N-benzylpyridinium spacers. The magnetic properties depend strongly on the nature of the metal center. The magnetic coupling through (μ-1,1-N3)(μ-1,3-COO)2 is antiferromagnetic in the Mn(II) compound but ferromagnetic in the Co(II) and Ni(II) analogues. Magnetostructural analyses indicate that the magnitude of the magnetic coupling can be correlated to the M-N-M angle of the azide bridge and the average M-O-C-O torsion angle of the carboxylate bridge. As the values of these parameters increase, the antiferromagnetic coupling for Mn(II) decreases while the ferromagnetic coupling for Co(II) increases. With strong magnetic anisotropy, the Co(II) compound behaves as a single-chain magnet showing hysteresis and Glauber-type slow dynamics probably in the infinite-chain region, with Δ(τ)/k = 86 K, Δ(ξ)/k = 26 K, and Δ(A)/k = 34 K. With weaker anisotropy, the Ni(II) species shows slow relaxation of magnetization at much lower temperature.

Solvothermal synthesis, crystal structure, and characterization of two new 2D Co(II)/Ni(II) coordination polymers with mixed-organic tectonics

Two new isomorphous coordination polymers [Co(4,4′-Bpda)(Dpa)] n (I) and [Ni(4,4′-Bpda)(Dpa)] n · H2O (II) (4,4′-H2Bpda = benzophenone-4,4′-dicarboxylic acid, Dpa = dipyridin-4-ylamine) were synthesized under solvothermal condition and characterized by elemental analysis, FT-IR and single-crystal X-ray diffraction technique. Compounds I and II exhibit 2D helical layers resulting from alternating single helical chains and double helical chains, which feature uninodal 4-connected topology with a point symbol of 66.

Effects of isomorphous substitution of a coordination polymer on the properties and its application in electrochemical sensing

This work concerns the isomorphous substitution of coordination polymers (CPs) and its effect on the optical and electrochemical properties. The application of CPs in electrochemical sensing was studied as well. Isomorphous coordination polymers, [CoxZn1−xtyr]n (tyr=l-tyrosine), where x (0–1) was controlled by the Co/Zn ratios of raw materials, were successfully synthesized via a hydrothermal method, as proved by XRD and EDS results. Their UV–vis DRS and fluorescence spectra change gradually along with the composition. Cyclic voltammograms of modified electrodes, [CoxZn1−xtyr]n/GCE, show that as more and more Zn replaced Co, the current signal decreases greatly and the potential shifts negatively. Much attention was paid to [Cotyr]n due to its highest sensitivity. Refreshable modified carbon paste electrode, [Cotyr]n-CPE, was used to determine nitrite, and showed pretty good performance as evidenced by chronoamperometry. The response was made very fast within mere 5s. The linear detection range was from 5.00×10−5 to 3.45×10−3M, with sensitivity of 263.4mAmol−1Lcm−2. The detection limit was found to be 2.00×10−5M. The sensor also showed good antiinterference and reproducibility.

Metal-ion controlled solid-state reactivity and photoluminescence in two isomorphous coordination polymers

Reactions of [M(NH3)2]OH (M = Ag and Cu) and 4-(1H-pyrazol-4-yl)pyridine (Hpypz), using p-xylene (C8H10) as the template, gave isomorphous two-dimensional porous metal azolate frameworks [Ag2(pypz)2]·0.5C8H10 (MAF-36(Ag), 1·g) and [Cu2(pypz)2]·0.5C8H10 (MAF-36(Cu), 2·g). Powder and single-crystal X-ray diffraction studies showed that, upon guest removal, 1·g transformed into a three-dimensional nonporous framework [Ag6(pypz)6] (1′), while 2·g can retain its porous two-dimensional structure. Depending on the metal ion, framework flexibility/rigidity, and/or porosity, 1·g and 2·g, as well as their guest-free derivatives, showed distinctly different photoluminescence and guest-responsive behaviors.

Construction of two chiral bilayer coordination polymers based on 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylate ligand

Two novel isomorphic coordination polymers [Zn(HPyImDC)H2O](1) and [Co(HPyImDC)H2O](2) were synthesized from 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid(H3PyImDC) under hydrothermal conditions. Both the compounds crystallized in P212121 chiral space group, possessing left-hand helical chains and right-hand helical chains. Two types of helical chains connected with each other to form an interesting 2D bilayer structure which extended to a 3D supermolecular structure via the hydrogen-bonding interactions. Topology analysis shows that H3PyImDC ligand and metal center can be regarded as 3-connected T-shaped nodes, thus leading to a (3,3)-connected network with vertex symbol of (82·10).

Coordination polymers based on trinuclear and mononuclear copper-pyrazolate building moieties connected by fumarate or 2-methylfumarate ions

By reacting water solutions of pyrazole (Hpz) with copper(II) fumarate or 2-methylfumarate in solvothermal conditions two almost identical trinuclear triangular complexes, [Cu3(μ3-OH)(μ-pz)3{R(COO)2}(Hpz)], [R = CHCH, C(CH3)CH], have been obtained. The two carboxylate groups of both fumarate and 2-methylfumarate show different arrangements, one acting as monotopic ligand while the other one has a ditopic behavior. Thus, in both cases, wavy 2D isomorphous Coordination Polymers (CPs), that further self-assemble through strong H-bonds into two 3D networks, have been obtained. When copper(II) 2-methylfumarate was reacted with pyrazole at r.t. the mononuclear [Cu(Hpz)2(H2O)(2-methylfumarate)·H2O] complex was, in addition, obtained. In this case the bridging dianions produce instead monodimensional CPs that self-assemble into supramolecular tapes mediated by H-bond interactions, involving coordinated and crystallization water molecules. The mononuclear and trinuclear species were preliminary tested as catalysts for the oxidation of styrene by H2O2.

Synthesis, crystal structures, and magnetic properties of three isomorphous helical coordination polymers

Three isomorphous coordination polymers of general formula {[M(H2bna)·(DMF)2·(H2O)2]·DMF}n (M = Co for 1, Mn for 2, Ni for 3, respectively, where H4bna = 2,2′-dihydroxy-[1,1′]-binaphthalene-3,3′-dicarboxylate) were synthesized under solvothermal conditions and characterized by FTIR, single crystal X-ray diffraction, thermogravimetric analysis, and X-ray power diffraction analysis. All three polymers crystallize in the same monoclinic space group P21/n. The complexes are assembled into 1D helical chains, and each adjacent helical chain of the same chirality is further connected to form a chiral layer by hydrogen bond interactions. The layers are packed in alternating left-(M) and right-handed (P) chirality arrays. Magnetic studies reveal the presence of antiferromagnetic coupling interactions in complexes 1 and 2.

Synthesis and Characterization of Three New Zipper‐like Lanthanide [Ln = TmIII, NdIII, CeIII] Coordination Polymers Containing 1,3‐Benzenedicarboxylate and 2‐Phenyl‐1H‐1,3,7,8‐tetraazacyclopenta[l]phenanthrene Ligands

AbstractReaction of the ligands 2‐phenyl‐1H‐1,3,7,8‐tetraazacyclopenta[l]phenanthrene (PTCP) and benzene‐1,3‐dicarboxylic acid (m‐H2BDC) with Ln2O3 under hydrothermal conditions lead to three isomorphous coordination polymers [Ln2(PTCP)2(m‐BDC)3·H2O]n (Ln = Tm, 1; Nd, 2; Ce, 3). The coordination polymers crystallize in monoclinic, space group P21/m with a = 9.8340(2), b = 17.9140(4), c = 15.6050(3) Å, β = 100.51(3)° for 1, with a = 9.8423(3), b = 18.3562(4), c = 15.6209(3) Å, β = 102.138(3)° for 2, and with a = 9.8620(2), b = 18.4960(4), c = 15.6530(3) Å, β = 102.42(3)° for 3, respectively. The metal ions (Ln3+) are located in an octacoordinated environment and the dinuclear [Ln2O12N4] units act as octahedral secondary building units (SBU), which are bridged in two coordination modes by six m‐BDC ligands to form a three‐strand‐like chain. These chains are decorated by PTCP ligands and form unique three zipper‐like structures, which are further assembled into three‐dimensional supramolecular nets by π···π stacking interactions. Additionally, hydrogen bonds are observed in the structures. Furthermore, compounds 1–3 were studied by IR spectrocopy and thermogravimetric analyses.

Isomorphic coordination polymers of cobalt(ii), zinc(ii) with a flexible ligand of cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid and their molecular alloys: crystal structures, thermal decomposition mechanisms and magnetic properties

Three new isomorphic coordination polymers of Co(2+), Zn(2+) ions with flexible multicarboxylic acid ligand of the cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid (H(4)L), [Co(4)L(2)(H(2)O)(8)]·3H(2)O (1), [Zn(4)L(2)(H(2)O)(8)]·3H(2)O (2) and [Co(0.8)Zn(3.2)L(2)(H(2)O)(8)]·3H(2)O (3), have been synthesized under hydrothermal conditions and by means of controlling the pH of the reaction mixtures (with an initial pH of 6.0 for 1, 4.0 for 2, and 5.0 for 3, respectively). In the crystal of 1, two crystallographically different Co(2+) ions (Co1 and Co2) form a negatively-charged coordination polymeric chain, which contains a centrosymmetric, linear, trinuclear Co(2+) cluster (Co(3)L(2)) subunit; another crystallographically independent Co(2+) ion (Co3) coordinated to six water molecules acts as a counter ions to link the neighboring coordination polymeric chains via intermolecular H-bond interactions. The Co(2+) ions in 1 were completely and partially replaced by Zn(2+) ions to give 2 and 3, respectively. Complex 3 shows a novel molecular alloy nature, due to the random distributions of the Co(2+) and Zn(2+) ions. Three isomorphic complexes exhibit distinct thermal decomposition mechanisms. The deprotonated cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid ligands decompose at 420-750 °C to give the residue CoO in 1, ZnO + C in 2 and CoO + ZnO in 3. Complex 1 shows a complicated magnetic behavior with co-existence of antiferromagnetic exchange interactions between neighboring Co(2+) ions as well as strong spin-orbital coupling interactions for each Co(2+) ion; complex 3 exhibits a magnetically isolated high-spin Co(2+) ion behavior with strong spin-orbital coupling interactions.

Poly[(μ4-2,5-dimethoxybenzene-1,4-dicarboxylato)manganese(II)] and its zinc(II) analogue: three-dimensional coordination polymers containing unusually coordinated metal centres

The title compounds, [Mn(C(10)H(8)O(6))](n) and [Zn(C(10)H(8)O(6))](n), are isomorphous coordination polymers prepared from 2,5-dimethoxyterephthalic acid (H(2)dmt) and the respective metal(II) salts. Both complexes form three-dimensional metal-organic frameworks with each M(II) centre bridged by four 2,5-dimethoxyterephthalate (dmt(2-)) anions, resulting in the same type of network topology. The asymmetric unit consists of one M(II) cation on a twofold axis and one half of a dmt(2-) anion (located on a centre of inversion). In the crystal structure, the M(II) centres are coordinated in a rather unusual way, as there is a distorted tetrahedral inner coordination sphere formed by four carboxylate O atoms of four different dmt(2-) anions, and an additional outer coordination sphere formed by two methoxy and two carboxylate O atoms, with each of the O atoms belonging to one of the four different dmt(2-) anions forming the inner coordination sphere. Consideration of both coordination spheres results in a super-dodecahedral coordination geometry for the M(II) centres. Besides the numerous M(II)···O interactions, both structures are further stabilized by weak C-H···O contacts.

An Atypical Network: Noninterpenetrating (10,3)-d Nets Using an Unsymmetrical Flexible Ligand and Ag(I) as Three-Connected Nodes

The flexible unsymmetrical thioether ligand 4-pyridylsulfanylmethyl-pyrazine (L) was prepared and reacted with AgX (X = BF4, ClO4, PF6) to form three isomorphous coordination polymers {[Ag(L)](X)}∞ that were characterized by X-ray crystallography. Topological analysis revealed that the compounds formed rare noninterpenetrated (10,3)-d (or utp) nets. The ligand was designed to act as a three-connected node and provided three nonplanar topological links to form an extended three-dimensional structure. A feature of the three structures was the invariance of the networks to the choice of anion. The indicators for distinguishing between (10,3)-a and (10,3)-d nets are discussed.

Interplay between covalent and aurophilic interactions in a series of isostructural 3D Hoffman-like frameworks containing bipyrimidine and dicyanoaurate bridges. X-Ray structure and magnetic properties of {(µ-Au(CN)2]2[(M(NH3)2)2(µ-bpym)]}[Au(CN)2]2(M = Ni(ii), Co(ii) and Cu(ii))

The isomorphous coordination polymers {micro-Au(CN)(2)](2)[(M(NH(3))(2))(2)(mu-bpym)]}[Au(CN)(2)](2) (M = Co(II) (1), Ni(II) (2), Cu(II) (3)) have been prepared from the reaction of 2 equiv. M(NO(3))(2) x nH(2)O (M = Cu(II), n = 3; M = Ni(II) and Co(II), n = 6) with 1 equiv. of bipyrimidine (bpym) in aqueous ammonia and then with an aqueous solution containing 1 equiv. of K[Au(CN)(2)]. The structures of these complexes are made of bpym bridged centrosymmetric dinuclear [M(NH(3))(2)(mu-bpym)M(NH(3))(2)] units connected by [Au(CN)(2)](-) anions to four other dinuclear units giving rise to a cationic 2D (4,4) rectangular grid network, its charge being balanced by two non-coordinated [Au(CN)(2)](-). The layers are stacked in such a way that the ammonia coordinated molecules are interdigitated and aligned above and below one sheet with cavities in neighbouring sheets, giving rise to an ABAB[dot dot dot] repeat pattern of layers. Gold atoms of bridging and non-bridging dicyanoaurate anions are involved in short aurophilic interactions (Au1-Au2 distances in the range 3.12-3.14 Angstrom), leading to a chain of gold atoms running along the a direction. Neighbouring gold chains are further connected by weaker aurophilic interactions (Au1-Au1 distances in the range 3.43-3.49 Angstrom), affording a honeycomb-like 2D network of gold atoms. The (4,4) rectangular sheets and (6,3) honeycomb sheets share the Au2 atoms, leading to a unique 3D network. Magnetic measurements clearly show the existence of antiferromagnetic exchange coupling between the metal ions with susceptibility maxima at 17 K (1), 22 K (2), and 17 K (3). The data of 1 were analyzed through a full Hamiltonian involving spin-orbit coupling, axial distortion, Zeeman interactions and magnetic exchange coupling between Co(II), and the best fit gives J = -9.23 cm(-1), kappa = 0.99, lambda = -142 cm(-1), Delta = -562 cm(-1). For 2 and 3, magnetic data were fitted to the theoretical equations derived from the isotropic Hamiltonian: H = -JS(1)S(2). The best fit parameters were g = 2.050(1), J = -17.51(1) and P = 0.01(2) for 2 and g = 2.068(5), J = -20.07(8) and P = 0.015(4) for 3, respectively (P takes into account the amount of paramagnetic impurity). In order to explain the weak magnetic interaction between copper(II) ions mediated by the bipyrimidine bridging ligand in 3, we have carried out electronic structure calculations based on the density functional theory (DFT).