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Three new amine functionalised tetracarboxylate linkers with a variety of arm lengths were synthesised, namely N,N,N′N′-tetrakis(R1, R2 or R3)-trans-1,4-diaminocyclohexane, R1 = (4-carboxyphenyl)-1-methyl; R2 = (4-cinnamic)-1-methyl; R3 = 1′-carboxy-[4,4′-biphenyl]-1-methyl. The diagonal length of the linkers, from single crystal structural analysis and obtained by measuring between the furthest oxygen atoms, is 19.4, 24.6 and 27.5 A for L1, L2 and L3, respectively. The sp3 hybridization of the amino groups of the cyclohexyldiamine core and the carbon atoms of methylene spacers permits the rotation of the attached groups to occur around these atomic sites, giving the ligands a flexibility that manifests itself in two main dominant conformations: convergent, where carboxyl arm groups connected to the same nitrogen atom are π⋯π stacking, and divergent, where two carboxyl arms occupy equatorial positions and two occupy the axial positions relative to the ligand's cyclohexyl core. Analysis of the overall ligand conformations obtained from crystal structures of sixteen new coordination polymers showed that the overwhelmingly most common conformation (93%) was the divergent one. The formulae and topologies of the coordination polymers obtained were: poly-[Cd2(H2L1)(Cl)2(OH2)2]·5H2O (1) 2D (4,4), poly-[M2L2(OH2)2]·DMA M = Cd (2Cd) or Mn (2Mn) 3D (4·62·7·8)(42·66·75·82), poly-[Cd2(L3)(OH2)4(DMF)2] (3) 1D ladder, poly-[Cd2(L3)]·4DMA·16H2O (4) 3D fsc, poly-{((CH3)2NH2)4[Zn4Na4(L1)4(OH2)4(DMF)2]} (5) 3D pts, poly-[M5(HL1)2(O)2(OH2)2(DMF)2]·solv M/solv = Zn/2DMF·18H2O (6Zn) or Co/9DMF·10H2O (6Co) 3D cyc, poly-[Zn3(L1)(OH)2]·2DMF (7) 3D fsc, poly-{((CH3)2NH2)[Zn2(HL2)(O)]·DMF} (8) 3D pts, poly-[Zn8(L3)3(O)2]·16DMF (9) 3D fsy, poly-[Cu2(L1)(DMF)2] (10) 2D (4,4), poly-[Cu2(L2)(OH2)2] (11) 3D lvt, poly-[Na4Zr2(L1)3(DMF)4] (12) 3D (44·52)2(44·5·6)(46·513·68·7)2, poly-[Zr6(HL1)2(O)8(CH3COO)2(OH2)6] (13) 3D scu, and poly-[Co2K4(L1)2(DMF)3] (14) 3D (42·64)(42·610·83). Although we applied similar reaction conditions, none of the coordination polymers obtained with L1, L2 & L3 were isoreticular upon ligand change. The overall trend is of void space increase by using longer ligands but with no notable increase in the level of interpenetration. The predictability and control of the obtained frameworks was hindered by the formation of non-default topologies due to the high flexibility of the tetracarboxylate linkers used and the variety of metal nodes observed.

The use of flexible ligands in coordination polymers provides both opportunities and unpredictability. A new series of flexible ligands derived from p-xylylenediamine, which vary in the positioning of carboxylic acid functional groups, have been found to form a series of coordination polymers and a discrete coordination complex. Use of the tetra-substituted meta-carboxylic acid ligand N,N,N′,N′-tetra(3-carboxybenzyl)-p-xylylenediamine, isolated as its dihydrochloride salt (H6M4pxy)Cl2, resulted in the simultaneous formation of two products from the same synthetic conditions. One of these products was a discrete cage-type coordination complex of the form [Cu4(M4pxy)2(DMF)2(OH2)] (1), while the other product was the two-dimensional coordination polymer poly-[Cu2(M4pxy)(OH2)2] (2). Synthesis utilising the tetra-substituted para-carboxylic acid ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-p-xylylenediamine dihydrochloride (H6P4pxy)Cl2, resulted in the formation of multiple two-dimensional coordination polymers, poly-[Cu2(P4pxy)(DMF)(OH2)]·2DMF·3H2O (3·2DMF·3H2O), poly-[Mn2(P4pxy)(DMA)2] (4), poly-[Co4(P4pxy)2(DMF)2(μ-OH2)2(OH2)2]·6DMF·4H2O (5·6DMF·4H2O) and poly-[Cd2(P4pxy)(OH2)2]·DMA·3H2O (6·DMA·3H2O). The last of these materials, a three-dimensional coordination polymer, was found to adsorb approximately 32 cm3 g−1 STP of CO2 at atmospheric pressure at 273 K.

This communication briefly reviews why network topology is an important tool (for understanding, comparing, communicating, designing, and solving crystal structures from powder diffraction data) and then discusses the terms of an IUPAC project dealing with various aspects of network topology. One is the ambiguity in node assignment, and this question is addressed in more detail. First, we define the most important approaches: the “all node” deconstruction considering all branch points of the linkers, the “single node” deconstruction considering only components mixed, and the ToposPro “standard representation” also considering linkers as one node but, if present, takes each metal atom as a separate node. These methods are applied to a number of metal–organic framework structures (MOFs, although this is just one example of materials this method is applicable on), and it is concluded that the “all node” method potentially yields more information on the structure in question but cannot be recommended as the o...

Fourteen three-dimensional (3D) lanthanide coordination polymers (CPs) with dicarboxylate mixed ligands, [Ln(fum)1.5(H2O)2]·0.5(H2bdc)·H2O (Ln = Sm (1), Tb (2)), [Ln2(fum)2(bdc)(H2O)4]·2H2O (Ln = Sm (3), Eu (4), Tb (5), Er (6)), [Ln(fum)0.5(bdc)] (Ln = Sm (7), Eu (8), Tb (9), Er (10)), and [Ln2(bdc)2(ox)(H2O)4]·0.7H2O (Ln = Sm (11), Gd (12), Tb (13), Dy (14)), have been synthesized hydrothermally from the self-assembly of lanthanide(III) ions (Ln3+), fumaric acid (H2fum), and terephthalic acid (H2bdc) in the presence of potassium hydroxide at different temperatures. The compounds fall into four classes. Compounds 1 and 2 were isolated from hydrothermal reactions performed at a relatively low temperature of 100 °C and found to crystallize in the triclinic space group P. The 3D framework is assembled from 2D layers of [Ln(fum)(H2O)2] units pillared by the chelating fum ligands and has 1D rhombic channels templated by H2bdc and lattice H2O molecules. The framework presents a binodal (4,5)-connected tcs topology with the point symbol (44·62)(44·66). Raising the reaction temperature to 140 °C resulted in the formation of compounds 3–6. These materials crystallize in the monoclinic system with the polar space group P21 and feature a 3D network constructed from dinuclear {Ln2(OCO)6(H2O)4} units interlinked by fum and bdc ligands, showing a uninodal 6-connected two-fold interpenetrated pcu topology. The small channels of the framework are occupied by lattice H2O molecules. Further increase of the reaction temperature to 160 °C gave rise to the formation of compounds 7–10, crystallizing in the orthorhombic space group Pbca. The 3D framework is generated from 2D corrugated sheets of [Ln(fum)]2+ bound by bdc ligands and contains no intercalated H2O molecules in the lattice. The framework possesses a trinodal (4,6,7)-connected net with the point symbol (42·64)2(46·68·8)(412·69)2. Finally, compounds 11–14 contained an in situ generated oxalate (ox) ligand formed under hydrothermal conditions conducted at a high reaction temperature of 180 °C. These compounds crystallize in the monoclinic space group P21/c and possess a 3D open framework consisting of a dinuclear [Ln2(ox)(H2O)4]2+ unit linked by bridging bdc ligands and has small void channels occupied by lattice H2O molecules. The frameworks were topologically simplified as a binodal (4,5)-connected tcj/hc net with a total point symbol of (42·52·72)(42·53·75). In the solid state at room temperature, the Tb (2, 5, 9, and 13) and Eu (4 and 8) compounds emit green and red light, respectively.

A new Cd(II) based metal–organic framework (MOF), having formula {(CH3)2NH2)6[Cd5(L)4]·H2O·3DMF}n (1), has been synthesized based on a rigid tetracarboxylate ligand of terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4L). 1 shows a complicated 3D tetranodal 3,3,4,8-c network with uncoordinated –COO− groups. The highly selective luminescent sensing of 2,4-dinitrophenol (2,4-DNP), 2,4,6-trinitrophenol (TNP) and ferric ions was studied for 1 through the alleviation in its fluorescence intensity. The detection limit of 2,4-DNP was found to be 0.84 ppm, which is 20 times higher than that of 1,3,5-trimethylbenzene, demonstrating greater and selective quenching ability. The possible mechanism associated with the decrease in fluorescence intensity of 1 in the presence of nitroaromatics (NACs) has been addressed by theoretical calculations. Furthermore, 1 displays excellent capacity to adsorb methylene blue (MB) with high selectivity, and it maintains an almost identical adsorption performance after being recycled five times.

A new metal–organic framework, formulated as {[Zn2(L)(DMF)3]·2DMF·2H2O} (1), has been synthesized using a symmetrical rigid carboxylate ligand terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4L). Single-crystal X-ray diffraction analysis shows that 1 possesses a 3D uninodal 4-c lonsdaleite (lon) topology based on binuclear Zn clusters. 1 behaves as a fluorescent chemosensor for highly selective and sensitive detection of Fe3+/Fe2+ ions, 2,4-dinitrophenol (2,4-DNP), p-nitrophenol (PNP) and 2,4,6-trinitrophenol (TNP). Furthermore, the photocatalytic properties of 1 for degradation of methyl violet (MV) and Rhodamine B (RhB) have been explored. The possible emission quenching of 1 in the presence of aromatic compounds has been addressed by theoretical calculations and the photocatalytic activity of 1 against organic dyes has been addressed using density of states (DOS) calculations.

A traditionally good chelating motif has been incorporated into a ligand for the synthesis of coordination polymers with vacant amine sites. A novel tetracarboxylic acid diamine ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-1,3-diaminopropane dihydrochloride trihydrate (H6L1)Cl2·3H2O, has been prepared, structurally characterised, and subsequently used in the formation of three new coordination polymers. Poly-[Cu2(L1)(OH2)2]·6DMF·3H2O 1 consists of (4,4) sheets formed by each L1 ligand coordinating to four copper(II) ‘paddlewheel’ dinuclear clusters. The amines of the ligand are non-coordinating. After solvent exchange and evacuation, 1 was found to adsorb approximately 23 cm3(STP) g−1 of CO2 at atmospheric pressure at 273 K. The isostructural compounds poly-[Zn(H2L1)(OH2)]·DMF·4H2O and poly-[Cd(H2L1)(OH2)]·DMF·3H2O 2Zn/2Cd are self-penetrating (10,3) coordination polymers containing square-shaped one-dimensional solvent channels. After solvent exchange it was found that 2Zn and 2Cd lost crystallinity, which accounts for the low N2 and CO2 uptakes observed.

An unexploited pentacarboxylate ligand, 2,5-bis(3′,5′-dicarboxylphenyl)-benzoic acid (H5L), was designed and used for the preparation of metal organic material using Zn2+ as a node. The new compound, {(Me2NH2)[Zn2(L)(H2O)]·0.5DMF}n (1) (DMF = dimethylformamide), has been synthesized and structurally characterized. The topology of the 5-connected anionic framework may be described as (44)(66) (Schlafli symbol) based on {M2(CO2)5} molecular building blocks (MBBs) and L ligands in 1. It has been demonstrated that 1 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+, with a detection limit of 0.54 ppm for 2,4,6-trinitrophenol (TNP) and 0.81 ppm for Fe3+. The possible emission quenching mechanism in the presence of nitroaromatics has been addressed by theoretical calculations.

A highly connected metal–organic framework (MOF), namely, [Co5(μ3-OH)2(iapt)4(4,4′-bipy)0.5(H2O)·CH3CN·3H2O] (1) (H2iapt = 5-aminoisophthalic acid and 4,4′-bipy = 4,4′-bipyridine), is reported. 1 shows a complicated pentanodal 4,4,4,4,13-c 3D net with (43)(43)(43)(43)(420·514·623·78·813) topology based on an uncommon Co5 cluster. The magnetic analysis reveals antiferromagnetic interactions in 1, and both the local spin–orbit coupling of octahedral Co(II) ions and the antiferromagnetic interactions are the primary factors in the magnetic behaviour.

A new divergent ligand, N,N′-bis(4-carboxyphenylmethylene)ethane-1,2-diamine (H4L1), has been prepared in high yield and used to generate two copper(II) coordination polymer materials, poly-[Cu(H2L1)(OH2)]·H2O (1) and poly-[Cu(H2L1)(OH2)]·H2O·DMF (2). Both networks possess (4,4) sheet topologies and have almost identical compositions and coordination modes. The only major difference between the compounds lies with the conformation of the chelating ethylenediamine cores; compound 1 adopts a trans-(R,R/S,S) conformation, while compound 2 exhibits a cis-(R,S) conformation. This seemingly small difference arising from variation in synthetic conditions influences the extended structures of each network through hydrogen bonding interactions, resulting in the formation of a close packed 2-fold 2D → 2D parallel interpenetrated network for 1, while the extended, non-interpenetrated structure of 2 contains aligned one-dimensional solvent channels. After solvent exchange and evacuation, compound 2 was found to adsor...

A new piperazine-derived ligand has been prepared and used to synthesise a porous coordination polymer which displays selective carbon dioxide uptake after solvent exchange and thermal activation. The ligand N,N′-bis(4-carboxyphenylmethylene)piperazine H2L1 was prepared from piperazine in three steps and good yield. A structure containing the deprotonated form K2L1·2H2O was determined and consists of a three-dimensional coordination polymer containing inorganic K2(COO)2(OH2) layers separated by the long organic bridging linker. The free compound H2L1 displays a one-dimensional hydrogen-bonded polymeric structure in the solid state with hydrogen bonding interactions between carboxylic acids and piperazine groups tightly linking molecules together. The two-dimensional polymeric complex [Zn3(L1)2(OH)2]·2DMF·0.5H2O 1 was prepared and analysed in the solid state to reveal tubular one-dimensional channels which, when activated by solvent exchange and evacuation, displayed selective affinity for CO2 over N2 and H2.

The utility of the pyrazole-carboxylate mixed ligand system has been probed with the synthesis of five new coordination polymers, derived from bis-pyrazole ligand 4,4′-methylenebis(3,5-dimethyl-1H-pyrazole) H2L1, large semirigid dicarboxylate coligands, and the deliberately designed and synthesized ligand para-((3,5-dimethyl-1H-pyrazol-4-yl)methylene)benzoic acid H2L4. Complex poly-[Co(H2L1)(L2)(OH2)]·1/2H2O 1 features the coligand (S,S)-1,4,5,8-naphthalenetetracarboxylic diimide-N,N′-bis(2-propionate) L2, and comprises chiral two-dimensional sheets, associating via substantial π–π stacking interactions. Complexes 2 and 3 contain the coligand 1,4-bis((3-carboxyphenyl)methyl)piperazine L3. Complex poly-[Co(H2L1)2(L3)] 2 is a two-dimensional polymer containing octahedral Co(II) ions, whereas modifying the synthesis conditions gave complex poly-[Co2(HL1)2(L3)] 3, a three-dimensional α-Po structure containing pyrazolate-bridged dimers of tetrahedral Co(II) ions, displaying weak antiferromagnetic coupling. Mag...

Examination of the crystal structures of (Me4N)(dcnm) (1), (Me4N)(dcnom) (2), and (Me4N)(nbdm) (3) [dcnm = dicyanonitrosomethanide, dcnom = dicyanonitromethanide, nbdm = nitroso-N,N-bis(dicyanometh...

Two isostructural series of compounds NH4[Ln(cdm)4(H2O)4]·18c6·3H2O (1Ln) and [K(18c6)(H2O)2][Ln(cdm)4(H2O)4]·H2O (2Ln) have been synthesised and structurally characterised (Ln = Gd, Dy, Er, cdm = C(CN)2(CONH2)−). These two classes of compounds are shown to be essentially isostructural to each other despite the change in counter-cation (ammonium vs. potassium) and the ensuing changes in coordination and hydrogen-bonding of water molecules in the structure. Structural data for 1Dy and 2Dy have been obtained using single crystal Laue neutron diffraction, allowing the precise location of all hydrogen atoms to be determined using fully anisotropic models. Both 1 and 2 contain the anionic complex [Ln(cdm)4(H2O)4]− in which the 8-coordinate lanthanoid is coordinated by a ring of four O-bound cdm ligands supported by inter-ligand N–H⋯O hydrogen bonds. The structures pack with complicated hydrogen-bonding networks in which both coordinated and non-coordinated water molecules are hydrogen-bond donors and all of the nitrile groups of the cdm ligands are hydrogen-bond acceptors. The change in cation between ammonium and potassium affects two water molecule sites which are both coordinated in 2Ln but not in 1Ln; in 1Ln one of these water molecules forms a hydrogen bond with NH4+ whilst the other has neither a coordination interaction nor a hydrogen bond to its oxygen atom.

The initial pH in the preparation of STA-16(Co) was found to have a great impact on the assembly of the MOF and the resulting porosity. The formation of a non-porous Co(II)-phosphonate pillared layer-structure was observed after changing the initial pH from 6.2 to 7.2 with distinct differences in the coordination environment of the cobalt centres.

Two new bis-(cyanobenzyl)piperazine ligands have been prepared, and have been used to prepare five Ag(I) coordination polymers which have been structurally characterised. Ligand N,N′-bis((4-cyanophenyl)methyl)piperazine L1 gave two structurally related two-dimensional coordination polymers poly-[Ag2(L1)(CF3SO3)2] 1 and poly-[Ag2(L1)(CF3SO3)2(C3H6O)1.5] 2 when reacted with silver trifluoromethanesulfonate in tetrahydrofuran and acetone, respectively. Compounds 1 and 2 display similar ligand geometries but form different extended networks, as a result of the inclusion of coordinating solvent molecules and the resulting influence on the flexible metal geometry. Reaction of N,N′-bis((3-cyanophenyl)methyl)piperazine L2 with silver ions gave rise to three new structurally characterised species. Complex poly-[Ag2(L2)(C3H6O)2]2(PF6) 3 forms a one-dimensional chain structurally related to 1. Complex poly-[Ag2(L2)(C3H8O)2(CF3SO3)2] 4 formed under similar conditions to 3, except with the inclusion of a coordinating anion which links equivalent chains to those found in 3 into a two-dimensional sheet. Finally, complex poly-[AgL2]CF3SO35 was formed simply by altering the reaction stoichiometry, producing a three-dimensional PtS network containing linear, acentric anion channels. Analysis of the structures reveals that the ligand geometries are largely consistent, leading to the extended structures being more influenced by the nature of the anions and solvent molecules.

Two divergent ligands 1,4,7,10-tetrakis-(4-cyanobenzyl)-1,4,7,10-tetraazacyclododecane L1 and 1,4,7,10-tetrakis-(4-carboxybenzyl)-1,4,7,10-tetraazacyclododecane dihydrochloride dihydrate H6L2·2Cl·2H2O have been prepared and structurally characterised, and the solid-state structures of four new metal complexes have been elucidated. Ligand L1 was found to form a dimeric complex of the form [Ag2(L1)2]·2ClO4 when reacted with silver perchlorate, in which a macrocycle-bound Ag(I) ion is coordinated by the nitrile group of an adjacent ligand, forming a tightly-bound pair of Ag(I) ions supported by intramolecular π–π interactions. Compound H6L2·2Cl·2H2O was prepared by a solvothermal recrystallization following hydrolysis of the ester precursor, and forms a densely packed three-dimensional structure containing numerous hydrogen bonding interactions. Complexes [Ni(H4L2)Cl]2·[NiCl4]·2EtOH 2 and [Co(H4L2)Cl]2·[CoCl4]·2EtOH 3 were characterised as isostructural discrete macrocycle-bound Ni(II) and Co(II) species where the formation of rare hydrogen-bonded carboxylic acid tetramers gives rise to a series of 2-dimensional sheets, containing checkerboard-type cavities encapsulating alternating tetrachloridometallate anions and regions containing disordered solvent molecules. Complex poly-{[Cu2Cl(H2L1)(HOEt)]2·[CuCl4]·5H2O} 4 consists of a series of two-dimensional sheets formed from a macrocycle-bound CuCl species linked by copper paddlewheel clusters and hydrogen-bonded carboxylic acid dimers. Charge balance is again achieved by tetrachloridometallate anions, and the sheets undergo parallel 2D → 2D interpenetration. The influence of the flexible geometry and donor ability of the methylene-linked pendant arms is clearly visible when comparing discrete complex 1 with hydrogen-bonded networks 2 and 3 and polymeric species 4. The presence of tetrachloridometallate counterions resulting from the presence of excess chloride ions in the reaction mixtures also provides powerful structure-directing effects in complexes 2, 3 and 4.

The variable-length azacrown ether bridging ligand N,N′-bis(3-pyridyl-methyl)diaza-18-crown-6 (b3pmdc) was reacted with cuprous iodide to give a range of new discrete and polymeric coordination compounds. Six structurally diverse CuI(b3pmdc) architectures were isolated, as well as a single oxidized CuII(b3pmdc) species. These include the helical one-dimensional (1D) chain [H4b3pmdc][Cu10I14]·CHCl3·2H2O (1), the luminescent linear cluster chain [Cu4I6(H2b3pmdc)] (2), the guest water containing network [Cu4I4(Hb3pmdc)2](1.5ClO4)(0.5I3)·3.5H2O·2.5MeOH (3), the luminescent cubane cluster chain [Cu4I4(b3pmdc)2] (4), the three-dimensional (3D) net [Cu9I12(Kb3pmdc)3(H2O)4]·9MeOH (5), the dinuclear mixed halide [Cu2Cl3.4I2.6(H4b3pmdc)] (6), and the cupric 1D chain [CuCl2(H2b3pmdc)(MeOH)2]·2Cl·2MeCN (7). Manipulation of the ligand conformation was achieved by the addition of the alkali metal salt potassium and by varying the pH of the solution with a range of acids (HCl, HClO4). In the case of 2 and 4, green and y...

Hexakis(4-cyanophenyl)[3]radialene (1) is a hexadentate ligand that has previously been shown to form isomorphous honeycomb two-dimensional (2-D) coordination polymers {[Ag(1)](X)·2(CH3NO2)}n (X = ClO4, 2a; X = PF6, 2b) upon reaction with AgClO4 and AgPF6. Within these coordination polymers, close contacts were observed between the anions and the electron-deficient [3]radialene core. Here the synthesis and characterization of four new coordination polymers of 1 and copper(I), {[Cu2(1)2](X)2·Y(CH3NO2)}n (X = BF4, Y = 20, 4a; X = PF6, Y = 14, 4b) and {[Cu(1)](X)·2(CH3NO2)}n (X = BF4, 5a; X = PF6, 5b), are reported, along with two further examples of the (6,3) network {[Ag(1)](X)·2(CH3NO2)}n (X = BF4, 2c; X = SbF6, 2d), and an 8-fold interpenetrated (10,3)-b net formed from 1 and AgClO4, {[Ag3(1)](ClO4)3·CH3NO2}n (3). Coordination polymers 2a–2d were synthesized using low ratios of ligand to metal, 1:1 to 1:3, whereas other examples described herein (compounds 3, 4, and 5) were obtained via the use of a cons...

A 3-fold interpenetrating porous metal–organic framework, namely, Zn(bdc)(L)·solvents (1, L = N4,N4′-di(pyridin-4-yl)biphenyl-4,4′-dicarboxamide, H2bdc = terephthalic acid), composed of self-catenated nets with unprecedented hxg-d-4-Fddd topology is reported. Upon removal of guest molecules, the crystal lattice is unaffected, and the resulting permanent porosity can be applied for gas chromatography separation of various organic molecules. Furthermore, remarkable tunable photoluminescence and direct white emission dependent on excitation wavelength, as well as visible light photocatalytic activity, are also observed, creating a new multifunctional material antetype.

Two unprecedented three-dimensional (3D) true coordination polymorphs, namely, [Pb2(phda)2(H2O)]n·2nH2O (1a, and 1b) (H2phda = 1,4-phenylenediacetate acid), which show distinct novel topological networks, have been successfully prepared by utilizing a kinked flexible H2phda. This work shows the first example of two different isomers reported for a flexible ligand acting as a bridge.

Six new neutral crystalline clusters Zn8S(SC6H5)14L2 [L = pyridyl (1), 3-(phenylthio)pyridyl (2), 4-(phenylthio)pyridyl (3), 3-iodopyridyl (4), 3-butylpyridyl (5), and phenanthridyl (6)] with Zn8S cores have been assembled by a hydrothermal process. Exceptionally, in situ ligand reactions have been observed in clusters 2 and 3. There are no detectable fluorescence emissions of complexes 1−5, whereas 6 shows an emission peak at 365 nm due to the existence of terminal phenanthridyl ligands.

Layered organic structures, containing robust hydrogen-bonded anionic tapes bridged by di- and triammonium cations, have been synthesized and structurally characterized. Salts of the carbamoyldicyanomethanide (cdm) anion, C(CN)2(CONH2)−, using H3N(CH2)nNH3 cations (n = 2, 3, or 4) display layered structures containing one-dimensional (1D) hydrogen-bonded chains of cdm. The structure of (H3N(CH2)2NH3)(cdm)2 (1) forms a bilayer structure with the cation bridging, through charge-assissted hydrogen bonds, between parallel anionic ribbons containing two different synthons. The longer cation in (H3N(CH2)3NH3)(cdm)2 (2) results in a structure containing parallel anionic layers with cationic pillars running through them. The layers in 2 contain different hydrogen bonded tapes with R22(8) and R22(16) ring synthons which are also observed in the structure of (H3N(CH2)4NH3)(cdm)2 (3). Despite the differing length of the cation in 2 and 3, the distances between the layers are remarkably similar; however, the extra de...

Seven three-dimensional (3D) cadmium coordination frameworks, {[Cd(5MT)2] (1a); [Cd5(N3)(5MT)9·0.12H2O] (1b); [Cd3(OH)Cl1.39(N3)0.61(5MT)3] (1c), 5MT = 5-methyl-tetrazole}; {[Cd3(OH)Cl(N3)(5AT)3 (2a); Cd2(OH)Br(5AT)2 (2b), 5AT = 5-amino-tetrazole]}; {[Cd7Cl2(5BT)12(H2O)2 (3a); and [Cd7Br2(5BT)12(H2O)2 (3b), 5BT = 5-butyl-tetrazole], were obtained through in situ tetrazole synthesis and have been structurally characterized by elemental analyses, Fourier transform infrared spectroscopy, thermal studies, and single crystal and powder X-ray diffraction. Compounds 1a and 1b were constructed by the interconnection of 5MT and cadmium metal ions, and both exhibited distinct topological nets: 1a has a diamond-like framework, while 1b has the acs topological net. Compounds 1c and 2a represented similar structural network motifs; both were intricate coordination polymers constructed from interconnected {ClCd3O} subnets through tetrazole anions. Compound 2b was constructed from two-dimensional (2D) wavelike {BrCd3O} ...

Five new coordination compounds, namely [Zn(Hbtc)(1,3-bix)(H2O)]n (1), {Zn2(µ-O)(btc)(timp)]·3(H2O)}n (2), {[Zn3(4,4′-bibp)2(btc)2(H2O)2]·4(H2O)}n (3), {[Ni3(4,4′-bibp)2(btc)2(H2O)2]·3(H2O)}n (4), {[Cu3(4,4′-bibp)2(btc)2(H2O)]·2(H2O)}n (5), where 1,3 - bix = 1- (3 - (1H -inidazol - 1 − yl)methyl)benzyl)-1H-imidazole, timp = 1- (3,5-di (1H-imidazol-1-yl)phenyl)-1H-imidazole, 4,4′-bibp = 4,4′-bisimidazolylbiphenyl, and btc = 1,3,5-benzenetricarboxylate anion, were synthesized under hydrothermal conditions. In compound 1, both 1,3-bix ligand and btc anion act as bidentate bridging ligands, and connect the zinc cations into a one-dimensional chain. In compound 2, timp and btc anions as tridentate ligands coordinate to zinc cations to form a three-dimensional 3,6-connected network. Compounds 3–5 have similar structures, 4,4′-bibp and btc anions act as bidentate and tetradentate ligands, respectively, and coordinate to metal cations to form a three dimensional 4,4-connected network. The luminescence properties for 1–3 and magnetic properties for 4–5 are also discussed in detail.

A couple of metal-organic frameworks (MOFs) constructed from rigid bicarboxylates are presented herein, namely, Co3(ndc)3(bbi)(CH3CN)2 (1) and Dy2Mn3(ndc)6(bipy)2 (2), where H2ndc = 2,6-naphthalenedicarboxylic acid, bipy = 2,2′-pyridine, and bbi = 1,1′-(1,4-butanediyl)bis(imidazole). These two coordination polymers have been prepared through solvo/hydrothermal reactions and characterized by single-crystal X-ray study, TG, IR, and elemental analysis. Polymer 1 features a novel self-penetrating network mediated by flexible long-chain ligand and well defines a unique 416·58·64 topology with the treatment of Co3 unit as an 8-connected node, which equals the highest connectivity for monometallic self-penetrating system so far. Polymer 2 represents the first example of a MnII−DyIII (3d-4f) heteropentanuclear complex showing an intriguing 3-D 36·418·53·6 framework upon the assignment of Dy2Mn3 cluster to an 8-connected node. In addition, magnetic studies of 1 reveal that the antiferromagnetic behavior is operati...

Twelve structurally diverse complexes, [Pb2(pzp)2(adip)(NO3)2] 1, [Pb(pzp)(glu)] 2, [Pb(pzp)(chdc)]·[Pb(pzp)(chdc)]·pzp·H2O 3, [Pb2(ndc)2(pzp)2(H2O)]·0.5H2O 4, [Pb(pzp)(1,3-bdc)(H2O)0.5]·H2O 5, [Pb(pzp)(1,2-bdc)]·H2O 6, [Pb2(ptc)2(adip)(NO3)2] 7, [Pb(ptc)(glu)] 8, [Pb(ptc)(chdc)] 9, [Pb(ptc)(dpdc)]2 10, [Pb(ptc)(1,3-bdc)]·2.5H2O 11, and [Pb(ptc)(1,4-bdc)]·0.75H2O 12, where H2adip = adipic acid, H2glu = glutaric acid, H2chdc = 1,4-cyclohexanedicarboxylic acid, H2ndc = 1,4-naphthalenedicarboxylic acid, 1,4-H2bdc = benzene-1,4-dicarboxylic acid, H2dpdc = 2,2′-diphenyldicarboxylic acid, 1,3-H2bdc = benzene-1,3-dicarboxylic acid, 1,2-H2bdc = benzene-1,2-dicarboxylic acid, pzp = pyrazino[2,3-f][1,10]phenanthroline, and ptc = 2-phenyl-1H-1,3,7,8,-tetraaza-cyclopenta[l]-phenanthrene, have been hydrothermally synthesized. Compounds 7 and 10 possess dinuclear structures, which are further extended by π−π interactions to form supramolecular layers and chains, respectively. 1−6, 8−9, and 11−12 feature chain structure...

To determine the influence of reaction conditions on the formation of metal−organic frameworks, a series of Co(II)/H2tbip/bpp complexes, {[Co2(tbip)2(H2O)6]·8H2O}n (1), {[Co(tbip)(bpp)(H2O)]2·4H2O}n (2), {[Co(tbip)(bpp)]·H2O}n (3), {[Co2(H2O)(tbip)(Htbip)2(bpp)2]·0.5(H2tbip)·0.5H2O}n (4), {[Co3(OH)(tbip)2(Htbip)(bpp)]}n (5) (H2tbip = 5-tert-butyl isophthalic acid, bpp = 1,3-bi(4-pyridyl)propane), have been synthesized through the hydrothermal reaction of cobalt(II) acetate, H2tbip, and bpp under different temperatures and pH conditions. The diverse product structures show the marked sensitivity of the structural chemistry of the aromatic carboxylate ligand to synthesis conditions. Polymer 1, which features a three-dimensional (3D) framework with CdSO4 topology, has carboxylate bridging polymeric chains spanning two different directions and bridging water molecules between these chains, and is formed at pH = 4 at 120 °C. At pH = 6, a one-dimensional tube-like structure of 2 is formed. Further increase of t...

A series of Zn(II) and Cd(II) metal−organic frameworks, namely, [Zn(DFDA)] (1), [Cd(DFDA)(C2H5OH)] (2), [Zn2(DFDA)2(L1)2]2·3H2O (3), [Cd2(DFDA)2(L1)2] (4), [Zn(DFDA)(L2)] (5), [Cd(DFDA)(L2)(DMF)] (6), and [Zn(DFDA)(L3)] (7) (where DFDA = 9,9-dipropylfluorene-2,7-dicarboxylate anion, L1 = 1,4-bis(imidazol-1-ylmethyl)benzene, L2 = 1,1′-(1,4-butanediyl) bis(imidazole), L3 = 2,2′-bipyridine) have been synthesized under hydrothermal conditions and structurally characterized. Compound 1 exhibits a three-dimensional (3D) framework containing one-dimensional (1D) Zn(II)-O clusters, with (48·67) topology. Compound 2 contains hydrophobic channels built from infinite 1D Cd(II)-O clusters, with (48·54·63) topology. Compounds 3 and 4 possess isomorphic two-dimensional (2D) layer structures which contain two kinds of rings, and the layers interdigitate extensively. Compound 5 features a 3D diamond-like structure that contains four interpenetrating networks. Compound 6 displays a 2D (4,4) topology. Compound 7 is compose...

Several CuII complexes of carbamoyldicyanomethanide (cdm, C(CN)2(CONH2)−) with various bidentate co-ligands have been prepared and characterised to examine the persistence of a previously observed dual-synthon ‘heterotape’ hydrogen-bonding motif that incorporates both amide and nitrile functionalities. Using 2,2′-bipyridine or 1,10-phenanthroline as co-ligands yields dimeric complexes of the form [Cu(cdm)Cl(L)]2·2MeOH (L = 2,2′-bipy 1 or 1,10-phen 2). However, the bridging species in these two dimers are different; μ2 chloride bridging in the bipyridine dimer and η1(N):η1(N′) cdm bridging in the phenanthroline complex. The subtle change in co-ligand prompts a change in the bridging mode that prevents the desired motif from forming in the phenanthroline structure, an effect that appears to arise from the greater π-stacking of the phenanthroline groups. The dimeric complex [Cu(cdm)(acac)(H2O)]23 and the monomeric complexes [Cu(cdm)2(NH2(CH2)3NH2)] 4 and [Mn(cdm)Cl(1,10-phen)2] 5 also fail to display the expected tape motif, although other complicated hydrogen bonding is present, and their structures are discussed.

A series of four- and six-connected entangled structures, namely [Cd(oba)(bbi)]·0.5H2O (1), [Ni(oba)(bbi)]2·H2O (2), [Co(bpea)(bbi)]·H2O (3), [Co2(bpea)2(bbi)2]·1.5H2O (4), [Cd(oba)(1,4-bix)] (5), and [Ni2(oba)2(1,4-bix)(H2O)2] (6), where oba = 4,4′-oxybis(benzoate), bpea = biphenylethene-4,4′-dicarboxylate, 1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, and bbi = 1,1′-(1,4-butanediyl)bis(imidazole), have been successfully synthesized through a hydrothermal process. The structures of 1 and 2 both consist of two interpenetrating CdSO4 nets. In 1, the two nets are related by symmetry. By comparison, the individual nets are, unusually, crystallographically distinct in 2. The structures of 3 and 4 both contain interpenetrating diamond networks. In 3, there are 6 interpenetrating nets, and they show the usual mode of interpenetration. For 4, however, there are 7 nets, and a rare ‘abnormal’ [4 + 3] interpenetration mode is observed. In 5, the oba and 1,4-bix ligands linked the Cd(II) atoms into a deeply corrugated 2D sheet. The corrugated 2D sheets polycatenate each other in a parallel manner with DOC (degree of catenation) = 2, yielding a rare 2D → 3D parallel polycatenation net. In 6, the dinuclear Ni(II) units are bridged by the oba ligands to generate a 2D (4,4) square-grid with a rhombic window. It is interesting that the two identical (4,4) square-grids show 2D → 2D parallel interpenetration but are then further crosslinked by the 1,4-bix ligands to yield an unusual 3D self-penetrating net with an unique 6-connected 44.611 topology. The importance of bbi conformations and metal sources in the framework formation of complexes 1–6 was unraveled. Their infrared spectra, powder X-ray diffraction (XRD) and photoluminescent properties were also investigated in detail.

A series of five salts of carboamoyldicyanomethanide, C(CN)2(CONH2)−cdm, have been synthesised and structurally characterised using different cations; ammonium (1), methylammonium (2), dimethylammonium (3), trimethylammonium (4) and tetramethylammonium (5). These organic salts vary in the degree of hydrogen-bonding interactions that the cation can partake in with minimal change in the size of the cation. The structure of 1 shows the NH4 cation involved in extensive hydrogen bonding to the cdm anions to form a 3D network with minimal interaction between anions and the disruption of previously observed supramolecular synthons that occur between cdm anions. In contrast to this the structure of 5 contains no hydrogen-bonding between cations and anions and leads to the formation of a corrugated sheet containing only interactions between neighbouring anions. The intermediate cases involving the MeH3N+ (2), Me2H2N+ (3) and Me3HN+ (4) cations, display a 2D hydrogen bonded sheet in the case of 2 and 1D chains in the structures of 3 and 4. The structure of a larger tetraalkylammonium salt, (Et3MeN)cdm (6) contains a similar sheet network to that of the Me4N+ compound with subtle changes due to the increase in size of the counter cation. The role of the steric bulk of the counter-cation has been further investigated by the synthesis of the benzyltrimethylammonium salt of cdm (7) in which the anions form a previously observed 1D chain motif and are well separated due to the bulk of the cation.

Two new 3D frameworks [(WS4Cu6Br4)(timp)8/3(H2O)40/3]n (1) and [(WS4Cu6Br4) (timtz)8/3(H2O)40/3]n (2), containing heptanuclear cluster blocks (one W atom and six Cu atoms) bridged by trigonal ligands timp or timtz (timp = 1-(3,5-di (1H-imidazol-1-yl)phenyl)-1H-imidazole; timtz = 2,4,6-tri(1H-imidazol-1-yl)-1,3,5-triazine), were successfully synthesized. Both compounds were characterized by single-crystal X-ray diffraction, elemental analysis, XRD, IR, TGA. X-ray determination shows that 1 and 2 can be topologically represented as (3,4)-connected networks with α-C3N4 (or ctn) topology where [WS4Cu6] act as the 4-connecting nodes, and the timp or timtz ligands bridge in pairs that act as the three-connecting nodes. Both compounds have the high symmetry of space group I-43d, which is the maximum symmetry for this net topology. The luminescent spectra and N2 absorption behaviors for 1 and 2 have also been investigated.

Two structurally related flexible bis(imidazole) ligands, 1,2-bis(imidazole-1-ylmethyl)-benzene (1,2-bix) and 1,4-bis(imidazole-1-ylmethyl)-benzene (1,4-bix), reacted with Cu(II) salts and various organic acids at room temperature, leading to the formation of nine novel metal-organic coordination architectures, from dinuclear structures to two-dimensional networks: [Cu2(CO3)2(1,2-bix)4]·8H2O (1), [Cu(L1)(1,2-bix)2]·2H2O (2), [Cu2(L2)(1,2-bix)2(H2O)4]·8H2O (3), [Cu(1,2-bix)2(H2O)2]·L3·4H2O (4), [Cu(L4)2][Cu(1,2-bix)2(H2O)2]·3H2O (5), [Cu(L5)(1,2-bix)]·H2O (6), [Cu2(L6)2(1,2-bix)2]·H2O (7), [Cu2(CO3)2(1,4-bix)3]·(1,4-bix)·10H2O (8), and [Cu(L6)2(1,4-bix)][Cu(1,4-bix)2(H2O)2]·4H2O (9) (H2L1 = 1,4-naphthalenedicarboxylic acid, H4L2 = 1,2,3,4-benzenetetricarboxylic acid, H2L3 = sebacylic acid, H2L4 = maleic acid, H2L5 = fumaric acid, and H2L6 = 1,3-benzenedicarboxylic acid). All complexes were structurally characterized by X-ray diffraction analysis. The formation of water clusters and the fixation of atmosphe...

This paper reports eight novel one-dimensional (1D) helical chain polymers consisting of metal salts and flexible bis(imidazole) ligands, formulated as [Co(L1)2(bimb)] (1), [Cu2(bimb)2Cl2] (2), [Co(L2)2(bimb)] (3), [Co(L3)(bix)Cl] (4), [Co(L4)2(bix)] (5), [Co(L5)2(bimb)] (6), [Ni(L6)2(bimb)] (7), and [Ni(L7)2(bimb)] (8) (bimb = 1,4-bis(imidazol-1-yl)-butane, bix = 1,4-bis(imidazol-1-yl-methylene)-benzene, HL1 = 3,5-dinitrobenzoic acid, HL2 = 4-methoxylbenzoic acid, HL3 = benzoic acid, HL4 = 4-methylbenzoic acid, HL5 = 3-nitrobenzoic acid, HL6 = 4-nitrobenzoic acid and HL7 = 4-chlorobenzoic acid), which have been obtained via hydrothermal reaction and characterized by single-crystal X-ray diffraction, elemental analysis, IR and thermogravimetric analyses. 1 consists of chiral polymer chains assembled from achiral components due to the presence of left-handed helices. 2 is a very unusual racemic compound based on perpendicular left- and right-handed helical chains. 3 contains two distinct types of helical c...

One new one-dimensional polymeric complex [Cd(C5H6N2)2(SeCN)2] n (1) has been synthesized and characterized by elemental analyses, spectroscopic studies and single crystal X-ray crystallography. Crystal structure shows the one-dimensional chain is propagated through doubly bridging selenocyanate and 4-aminopyridine acts as terminal ligand. The complex was characterized by fluorescence and NMR spectral studies and the results are consistent with the crystal structure.

A new long flexible ligand, L = 1,1′-(2,2′-oxybis(ethane-2,1-diyl))bis(1H-imidazole), has been prepared. The hydrothermal reactions of L with various metal ions (M(II) = Co, Zn, and Cd) as well as a series of aromatic polycarboxylate co-ligands yielded seven new metal−organic frameworks consisting of 1D, 2D, and 3D structures. Complexes 1–5 are constructed by SBU I (a M2L2 metallocycle), while complexes 6 and 7 are assembled by SBU II (left- and right-handed helical [M(L)]n chains). In 1and 2, the SBUs I are bridged by 1,2-BDC (1,2-benzenedicarboxylate) and 3,5-DNP (3,5-dinitrophthalate) anions with the same coordination modes to generate 1D chains with repeated rings. 3 exhibits a typically 3-fold interpenetrated 3-connected (10,3)-b net. In 4, the Co centers are connected by μ3-OH and carboxylic O atoms to form a cobalt−oxygen tetranuclear cluster. 5 represents an uncommon example of a 3,4-connected net with (83)2(85 × 10) topology. In 6, the SBUs II are extended by 1,4-BDC (1,4-benzenedicarboxylate) an...

Two 1D coordination polymers of copper(II) acetylenedicarboxylate, [Cu(O2CCCCO2)(C5H5N)2(MeOH)] (1) and [Cu(O2CCCCO2)(Me2C5H3N)2(MeOH)]·MeOH (2), have been synthesised and structurally characterised by single crystal X-ray diffraction. In both cases the square pyramidal CuII atoms have trans coordinated pyridyl ligands and trans η1 carboxylates in the equatorial sites with methanol occupying the apical position. The linear dicarboxylate ligand results in the formation of near linear coordination polymers. The polymeric chains in 1 form 2D hydrogen bonded (4,4) sheets whereas in 2 this topology is not possible, due to the extra steric bulk of the pyridine methyl groups, and a 3D hydrogen bonded network with CdSO4 (cds) topology is formed in which the lattice methanol molecules are also incorporated into the hydrogen bonding bridges.

Reported herein is the synthesis and structural characterisation of the novel ligand, 4,4′,6,6′-tetracarboxylic acid-2,2′-bipyridine (H4tcbp), along with an investigation of its coordination chemistry. Single crystal X-ray diffraction studies showed H4tcbp crystallises as a dihydrate and that intermolecular hydrogen bonding involving adjacent 4,4′-carboxylic acid groups form a R22(8) dimer motif whereas the 6,6′-carboxylic acid groups hydrogen bond together via the lattice water molecules [R44(12)] to form a 2D grid which is 3-fold interpenetrated and yields a 3D hydrogen bonded network. The reaction of H4tcbp under solvothermal conditions in MeOH with Ln(III) (Ln = Yb, Gd and Sm) lead to the isolation of {[Yb(Me2tcbp)2]·H2O·MeOH·H3O}, 1, and {[Ln(Me2tcbp)2]·2H2O·H3O}, where Ln = Gd, 2, or Sm, 3, and when in the presence of Yb(III) and Cu(II) to the mixed-metal species, {[Yb2(Me2tcbp)2]2Cu(OMe)2(H2O)2]·6MeOH}, 4, which were structurally characterised. Under these synthetic conditions the H4tcbp ligand di-esterified in situ at the remote 4- and 4′-carboxylic acid groups to form the 4,4′-dimethylcarboxy-6,6′-dicarboxy-2,2′-bipyridine ligand (Me2tcbp2–). Although 1 is monomeric, extensive hydrogen bonding between lattice water molecules, hydronium counterions and deprotonated carboxylate oxygen atoms results in 2D bilayer structure. Isostructural 2 and 3 are discrete mononuclear complexes whereas the tri-nuclear 4 forms a 2D sheet through face-to-face π–π interactions between adjacent units. In addition, the structural characterization and thermal analysis of four alkaline earth metal 3D coordination networks are reported, two of which feature the H4tcbp ligand: [Ba2(tcbp)(H2O)2] 5 and [CuSr(tcbp)(H2O)3] 6 (a 5,6-connected net), with the remaining two featuring the related 4,4′-dicarboxy-2,2′-bipyridine (H2dcbp) ligand: {[Ba(dcbp)(H2O)0.4]·0.6H2O} 7 (a bi-nodal 6-connected net) and {[Sr(dcbp)]·H2O} 8 (a uni-nodal 6-connected net).

The reaction of copper(II) chloride dihydrate with 2-hydroxy-3-methoxybenzaldehydethiosemicarbazone (HL) ligand in a 1:1 ratio forms the complex [Cu(L)(Cl)] · H2O. The complex is characterized by spectroscopic, electrochemical, and thermal analysis. X-ray crystallographic analysis reveals that the central copper atom displays the distorted square planar geometry. The water molecule present in the lattice participates in a strong hydrogen bonding network, which leads to a 2D supramolecular arrangement.

Using nonsubstituted 1,2,4-triazole and the second bridging ligands as coligands, a series of three-dimensional metal–organic frameworks based on different secondary building units (SBUs), namely, Zn2(trz)3(SCN) (1), Zn2(trz)2(ox) (2), Cd3(trz)2(suc)Cl2(3), [Cd5(trz)6(OAc)2Cl2(H2O)2]·2H2O (4), and [Zn7(trz)6(1,2,4,5-BTC)2(H2O)6]·8H2O (5) (trz = 1,2,4-triazole, ox = oxalate, suc = succinic acid, 1,2,4,5-BTC = 1,2,4,5-benzenetetracarboxylate), have been synthesized and structurally characterized with the aid of single-crystal X-ray diffraction. The SBUs in 1–5 vary from mononuclear, binuclear, linear trinuclear, linear pentanuclear to heptanuclear d10-1,2,4-triazolate polynuclear clusters. Compound 1 presents a complicated 3,6-connected topology based on three nonequivalent nodes. Compound 2 adopts a 6-connected 3D network of distorted α-Po topology that is built from dizinc units. The structure of 3 consists of two intersecting (4,4) grids which generate a novel self-penetrating 4,8-connected net with (456...

We have reported herein the synthesis of three new Cu(II) complexes of tri- and tetradentate Schiff base ligands containing N3 or N4 donor set along with terminal NNN− or SCN− ligands: [L1Cu(NCS)]ClO4 (1), [L2Cu(NCS)2] (2) and [L3Cu(NNN)]ClO4 (3) [L1 = NC5H4C(CH3)=N(CH2)3N=C(CH3)C5H4N, L2= Me2N–(CH2)3–N=C(CH3)C5H4N and L3 = NC5H4CH=N–(CH2)4–N=CHC5H4N]. The complexes have been systematically characterised by elemental, spectroscopic and electrochemical techniques. Antimicrobial activities of the Schiff base ligands and their metal complexes have been studied using the disc diffusion method on the strains of Candida tropicalis and Bacillus megaterium. Structures of all the complexes have been unequivocally established from single crystal X-ray diffraction analyses that show the monomeric units containing a five-coordinated copper center in highly distorted square pyramidal geometry with thiocyanate or azide anion coordinated as terminal ligand. The complexes 1 and 3 crystallise in monoclinic (P21/c) and 2 in triclinic (P-1) space group, respectively.

Six coordination polymers were prepared by linking Mn(SCN)2 units by three different bis(4-pyridyl) substituited hydrazone derivatives (L) in three different solvents (methanol, ethanol, and acetonitrile) in order to study the effect of the hydrogen bonding ability of L on the formation of solvates rather than interpenetrated solvent-free interpenetrated structures. When the ligand L which cannot act as a hydrogen donor was used, in all three solvents the same product was obtained. This was a [Mn(SCN)2L2]n metal–organic framework, consisting of two-dimensional (2D) networks, each interpenetrating two neighboring ones. When the bridging ligands L have additional functional groups capable of acting as hydrogen donors or acceptors, synthesis from acetonitrile yields non-interpenetrating 2D [Mn(SCN)2L2]n networks with solvent molecules occupying the voids of the network. Other solvents were found to yield interpenetrated solvent free networks, or they replaced some of the L ligands, forming one-dimensional coordination polymers.

Two new complexes [CuBr(C11H13N2O)] (1) and [Cu(NCO)(C11H13N2O)] (2) containing the tridentate Schiff base ligand, N-(1-acetyl-2-propylidene)(2-pyridylmethyl) amine which is the 1:1 condensation product of acetylacetone and 2-aminomethylpyridine, have been synthesised and characterised by elemental analysis, IR and electronic spectra, electrochemical study and single crystal X-ray diffraction study. Crystal structures reveal that the copper atom in both the complexes are in square geometry formed by the N2O donor set of the Schiff base and a bromine atom in 1 and one cyanate ligand in 2. Both bromide and isocyanate ligands act in a terminal monodentate fashion.

This article discusses the challenges that face the crystal engineer in the deliberate design of new network structures. These include control over ligand and metal coordination geometry, selection of network topology from a number of possibilities which all have the same connectivity, and control of methods of increasing packing efficiency, including interpenetration (both number of nets (including only one) and topology of interpenetration). These variables can lead to polymorphism and related phenomena, the bane of crystal engineers. Templation by counterions, guest molecules and/or solvents can also lead to unpredictable results.

Two structurally related flexible bis(imidazole) ligands, N,N‘-(1,1-methyl)bis(imidazole) (L1) and N,N‘-(1,4-butanediyl)bis(imidazole) (L2) reacted with AgI, CuII, ZnII, and CdII salts under hydrothermal conditions (except for 2 at room temperature), resulted in the formation of eight novel metal−organic coordination architectures, from one-dimensional (1D) chain to three-dimensional (3D) network structures: {[Ag(L1)2]ClO4}n (1), {[Cu(L1)2(H2O)2]Cl2(H2O)0.5(acetone)}n (2), {[Cu(L1)2](BF4)2}n (3), {[Cu(L1)2](ClO4)2}n (4), {[Zn(L1)3](ClO4)2}n (5), {[Cd(L1)3](ClO4)2}n (6), {[Cd(L1)2](N3)2}n (7), and {[Zn(L2)2](ClO4)2}n (8). All complexes have been structurally characterized by X-ray diffraction analysis. In 1, the AgI centers are two-coordinate with linear geometry and L1 ligands bridge the AgI centers to form 1D single helical chains. 2 and 7 have 1D double chain structures with the central metal ions being six-coordinated by four discrete L1 and two apical ligands (water molecules for 2 and N3- for 7). 3 ...

Three-dimensional (3-D) metallo-supramolecular architectures 1−3 based on CuII−dca−cypy systems [dca = dicyanamide, N(CN)2-, and cypy = n-cyanopyridine (n = 4, 3, 2)], which are extended by combining metal-coordination and second-sphere hydrogen-bonded interactions, were rationally designed and structurally characterized by single-crystal X-ray diffraction. Reaction of CuII with dca and 4- or 3-cypy afforded two similar neutral one-dimensional (1-D) coordination polymers, [Cu(dca)2(4-cypy)2]n (1) and [Cu(dca)2(3-cypy)2]n (2), in which the octahedral CuII centers are linked through double μ1,5-dca bridges and the cypy moieties act as monodentate terminal ligands via their pyridyl nitrogen donors. The coordination chains of 1 and 2 are further cross-linked by C−H···N interactions between the free nitrile N atoms of cypy and H atoms of the pyridyl ring, creating two interpenetrating 3-D networks (for 2, further weaker hydrogen-bonding interactions between the amide N atoms of dca and the H atoms in 3-cypy co...

The reaction of MnCl2·4H2O and 2,5-dimethylpyrazine-dioxide (2,5-dmpdo) with various anions in H2O affords different complexes, the solid structures of which are controlled by the choice of counteranions. Reaction of MnCl2·4H2O and 2,5-dmpdo with NH4NCS yields [Mn(NCS)2(2,5-dmpdo)1.5(H2O)2]·0.5(2,5-dmpdo)·H2O (1), which contains Mn(II) dimers bridged by 2,5-dmpdo. However, with the replacement of NH4NCS with NaN3 or sodium dicyanamide (Na(dca)) in the above reaction, Mn(N3)2(2,5-dmpdo)(H2O)2 (2) or Mn(dca)2(2,5-dmpdo) (3) was isolated. Compound 2 consists of a one-dimensional zigzag chain constructed by 2,5-dmpdo bridging ligands. Compound 3 is comprised of two-dimensional layers constructed by bridging 2,5-dmpdo and dca ligands. These results unequivocally indicate that the nature of the counteranions, which play different roles in each complex, is the key factor governing the structural topologies of them. While using 2,3-dimethylpyrazine-dioxide (2,3-dmpdo) instead of 2,5-dmpdo, [Mn(dca)2(2,3-dmpdo)]·H...

The crystal structures of M(dca)2(Mepyz)2·H2O, M = Co (1), Ni (2), dca = dicyanamide, N(CN)2-, and Mepyz = methylpyrazine; [Mn(dca)2(Mepyz)2][Mn(dca)2(Mepyz)]2·2MeCN (3); and Mn2(dca)3(NO3)(Mepyz)2 (4) are reported. Compounds 1 and 2 are isomorphous and consist of two-dimensional (2D) (4,4) sheets, with bridging μ1,5-dca ligands and trans-disposed monodentate Mepyz ligands. Compounds 3 and 4 were obtained as an intimate mixture from the same reaction mixture. Compound 3 contains both one-dimensional (1D) chains, in which Mn atoms are bridged by double μ1,5-dca bridges and the Mepyz ligands are trans and monodentate, and 2D (4,4) sheets, in which similar 1D chains are connected by bridging Mepyz ligands. The structure of 4 contains two interpenetrating 4,6-connected three-dimensional networks, with bridging μ1,5-dca anions, bridging Mepyz ligands, and chelating NO3- anions. Only very weak coupling and no long-range magnetic ordering intrinsic to these materials were observed for 1 or 2, although traces of ...