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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.

Two new isomeric bis(tacn) ligands, 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)-1-(hydroxymethyl)-benzene (HLhyx) and 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)anisole (Lanx) have been synthesised. In addition, 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)-4-methylphenol (HLohx) was also synthesised in a considerably higher yield than the previously reported method. The ligands were reacted with two equivalents of Cu(NO3)2·3H2O at pH 5 resulting in the formation of three binuclear complexes. The ligands Lanx and HLhyx form complexes [Cu2Cl3(L)(H2O)](PF6) containing two unique Cu2+ centres coordinated to the ligand. In contrast, the phenolic HLohx ligand forms a bridged complex [Cu2(μ-Cl)(Lohx)](PF6)2, with the two Cu centres further linked by (μ-Cl) and (μ-O) bridges.

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 metal–organic framework having formula {[NH2(CH3)][Cu6(L)3(OAc)(H2O)4]·xsolvent} (H4L = 3,5-bis(isophthalic acid)-1H-1,2,4-triazole) (1) was synthesized, in which two types of polyhedral cages and one-dimensional channels coexist. The incorporation of the drug 5-fluorouracil (5-FU) into the desolvated 1 was around 24.9 wt% per gram of dehydrated 1. 5-FU is released in a controlled and progressive fashion with 98% of the drug released after 120 h at PBS. The result from this work provides a new avenue for MOF to be used as potential drug delivery.

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...

In a study of multifunctional ('hybrid') molecular materials, with one function being spin-crossover and the second being reversible redox behaviour, we describe ferrocene-appended ligands and their d(6) and d(7) complexes trans-[Fe(II)(FTP)2(NCS)2] (1), [Co(II)(FTTP)2](ClO4)2·2(MeCN) (2) and [Fe(II)(FTTP)2](ClO4)2·Et2O (3) (where FTP = 4-(2-pyridyl)-1H-1,2,3-triazol-1-ylferrocene and FTTP = 4'-ferrocenyl-2,2':6',2''-terpyridine). The structures, magnetism and solution electrochemistry are described. Complex 1 remains high-spin, 2 displays gradual, incomplete spin crossover and 3 remains low-spin between 350-2 K. The electrochemical results show that one-electron oxidations at the ferrocene group, located external to the coordination site, occur at more positive potentials than the 'inner' M(II/III) couple in 1 and 2, but not in 3, and this has implications for retaining and influencing spin transitions at the M(II) centres, in future.

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.

Conventional bench top and solvothermal synthesis are determined to be reliable methods in the synthesis of coordination compounds containing the dicyanonitromethanide (dcnom) anion. From conventional bench top synthesis, [Ni(phen)3](dcnom)2 (1a), [Cu(phen)3](dcnom)2 (1b), [Cu(en)3](dcnom)2 (4), [Cu3(Hpz)3(H2O)(OH)(pz)3]Cl(dcnom)·H2O (7) and [Ag(Hpz)2(dcnom)] (8) (where phen = 1,10-phenanthroline, en = 1,2-ethylenediamine, Hpz = pyrazole and pz = pyrazolate) are obtained. With solvothermal synthesis, [Ni(phen)2(H2O)(dcnom)](dcnom) (2), [Cu(phen)2(dcnom)](dcnom) (3), [Cu(en)2(dcnom)2] (5) and [Cu(pn)2(dcnom)2] (6) (where pn = 1,3-propylenediamine) are formed. Both nitro κ1(O) and nitrile κ1(N) coordination modes are observed for the dcnom anion.

Metal cluster core expansion at tetrahedral group 6-group 9 mixed-metal clusters MIr3(μ-CO)3(CO)8(η(5)-L) (M = W, Mo, L = C5H5; M = Mo, L = C5Me5) with the iridium capping reagents Ir(CO)2(η(5)-L') (L' = C5Me5, C5Me4H) in refluxing toluene afforded the trigonal-bipyramidal clusters MIr4(μ-CO)3(CO)7(η(5)-C5H5)(η(5)-L') (M = Mo, L' = C5Me5, 1a; M = W, L' = C5Me5, 1b; M = Mo, L' = C5Me4H, 1c; M = W, L' = C5Me4H, 1d) and MoIr4(μ3-H)(μ-CO)2(μ-η(1):η(5)-CH2C5Me4)(CO)7(η(5)-C5Me5) (2). Related reactions with M2Ir2(μ-CO)3(CO)7(η(5)-L)2 (M = W, Mo, L = C5H5; M = Mo, L = C5Me5) afforded M2Ir3(μ-CO)3(CO)6(η(5)-C5H5)2(η(5)-L') (M = Mo, L' = C5Me5, 3a; M = W, L' = C5Me5, 3b; M = Mo, L' = C5Me4H, 3c; M = W, L' = C5Me4H, 3d), W2Ir3(μ-CO)4(CO)5(η(5)-C5H5)2(η(5)-C5Me4H) (4), and Mo2Ir3(μ-CO)3(CO)6(η(5)-C5Me5)3 (5). Single-crystal X-ray diffraction studies of 1a-1d, 2, 3a-3d, and 4 confirmed their molecular structures, including the μ-η(1):η(5)-CH2C5Me4 ligand at hydrido cluster 2, derived from a C-H bond activation of one of the methyl groups. Density functional theory (DFT) studies were employed to suggest the structure of 5. The redox behavior of the new clusters was examined through cyclic voltammetry; all clusters exhibit oxidation and reduction processes (with respect to the resting state), with the oxidation processes being the more reversible, and increasingly so on decreasing Ir content of the clusters, replacing W by Mo, and increasing alkylation of the cyclopentadienyl ligands. In situ IR and UV-vis-near-IR spectroelectrochemical studies of the reversible oxidation processes in 1a and 3a were undertaken, with the spectra of the former suggesting progression to an all-terminal CO geometry concomitant with the first oxidation and a significant structural change upon the second oxidation step. DFT studies of 1a revealed that its crystallographically-confirmed Mo-equatorial core geometry is essentially isoenergetic with a possible Mo-apical isomer, and identified several bridging CO structures for the charged states.

The transition metal-promoted in situ nucleophilic addition of methanol and ethanol to a nitrile arm of dicyanonitrosomethanide (dcnm) resulted in the formation of cyano[imino(methoxy)methyl]nitrosomethanide (cmnm) and cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) respectively. In the presence of 4,4′-bipyridine (4,4′-bipy), [Ni(cmnm)2(4,4′-bipy)]·½DMF (1), [Ni(cenm)2(4,4′-bipy)]·EtOH (2) and [Zn(cmnm)2(4,4′-bipy)]·2H2O (3) were isolated as 1D chains. When copper ions were used, a dinuclear structure, namely [Cu2(cmnm)4(4,4′-bipy)] (4) was observed. Synthesis of 1, 2 and 4 also required the presence of CeCl3·6H2O. The cmnm ligands in complex 3 display unique coordination modes to the metal ions, namely κ2(N,O)Zn. Finally, the hydrogen bonding in 3 generates three interpenetrating 3D networks with unusual bsn (or β-Sn) net topology.

This review gives an account of the coordination polymers that can be attained with ligands containing the sulphur-based dithiocarbamate (dtc), dithiocarboxylate and xanthate functional groups. The coordination modes adopted by the different sulphur-based ligands are discussed, and methods of attaining higher dimension complexes outlined. The review also addresses potential applications of such materials.

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...

Three manganese clusters have been synthesised via the reaction of Mn II with cyano(imino(methoxy)methyl)nitrosomethanide (cmnm), obtained from the in situ nucleophilic addition of MeOH to dicyanonitrosomethanide (dcnm). X-ray crystallographic studies show that the complex [Mn II 3 (cmnm) 6 ]·MeOH ( 1 ) is a linear trinuclear species, with a central octahedral and two outer trigonal-prismatic manganese(II) ions. Two mixed-valent tetranuclear complexes [Mn II 2 Mn III 2 O 2 (cmnm) 4 Cl 2 (MeOH) 6 ] ( 2 ) and [Mn II 2 Mn III 2 O 2 (cmnm) 4 Cl 2 (MeOH) 4 (pzH) 2 ]·2MeOH ( 3 ) (pzH = pyrazole) contain two Mn II and two Mn III ions in butterfly-type structures, with the six-coordinate ‘body’ Mn III ions bridged to the seven-coordinate ‘wingtip’ Mn II ions by μ 3 -O 2− and by nitroso oxygen atoms of the cmnm ligands. The formation of the trinuclear and tetranuclear manganese clusters is dependent on the stoichiometry used in the reactions. Solid state DC magnetic susceptibility studies on complexes 1 and 3 reveal that antiferromagnetic interactions are dominant within the clusters. Fits of the data reveal an S = 5 / 2 ground state for 1 and a S = 0 ground state for 3 , with several close lying excited states found in both cases.

A long and highly flexible internally functionalized dipyridyl ligand α,α'-p-xylylenebis(1-(4-pyridylmethylene)-piper-4-azine), L, has been employed in the synthesis of a series of coordination polymer materials with Co(II), Cd(II), and Ag(I) ions. In poly-[Cd(L)(TPA)] 1 and poly-[Co(L)(IPA)], 2, (TPA = terephthalate, IPA = isophthalate) the ligand adopts a similar linear conformation to that seen in the structure of the unbound molecule and provides a long (2.6 nm) metal-metal bridging distance. Due to the mismatch of edge lengths with that provided by the carboxylate coligands, geometric distortions from the regular dia and (4,4) network geometries for 1 and 2, respectively, are observed. In poly-[Ag2(CF3SO3)2(L)], 3, the ligand coordinates through both pyridine groups and two of the four piperazine nitrogen donors, forming a high-connectivity 2-dimensional network. The compound poly-[Ag2(L)](BF4)2·2MeCN, 4, a porous 3-dimensional cds network, undergoes a fascinating and rapid single-crystal-to-single-crystal rearrangement on exchange of the acetonitrile guests for water in ambient air, forming a nonporous hydrated network poly-[Ag2(L)](BF4)2·2H2O, 5, in which the well-ordered guest water molecules mediate the rearrangement of the tetrafluoroborate anions and the framework itself through hydrogen bonding. The dynamics of the system are examined in greater detail through the preparation of a kinetic product, the dioxane-solvated species poly-[Ag2(L)](BF4)2·2C4H8O2, 6, which undergoes a slow conversion to 5 over the course of approximately 16 h, a transition which can be monitored in real time. The reverse transformation can also be observed on immersing the hydrate 5 in dioxane. The structural features and physical properties of each of the materials can be rationalized based on the flexible and multifunctional nature of the ligand molecule, as well as the coordination behavior of the chosen metal ions.

The dicyanonitrosomethanide (dcnm) ligand undergoes an in situ transition metal promoted nucleophilic addition of methanol to a nitrile group to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) in the formation of the 3d/4f heterometallic complexes (Me4N)[{Ni(cmnm)3}2Ln(cmnm)2] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm). A change in the counter-ions of the metal and ligand salts employed under alternate reaction conditions results in the formation of (Et4N)2[{Ni(cmnm)3}2Ln(dcnm)2](ClO4) (2Ln; 2Ln = 2La, 2Ce), in which unreacted dcnm ligands are coordinated to the central lanthanoid. In both types of complexes three cmnm ligands chelate to a nickel metal centre to form a [Ni(cmnm)3] metalloligand. Two of these metalloligands are then bound to a central lanthanoid via the nitroso oxygen atoms, resulting in a trinuclear complex in which each nickel cation is connected to the lanthanoid by three bridging nitroso groups. Variable temperature magnetic susceptibilities on these {Ni(S = 1), Ln(f0 to f5), Ni(S = 1)} spin systems reveal very weak to zero Ln–Ni or Ni–Ni exchange coupling with the thermal depopulation between Stark levels on the Ln centres being of similar magnitude, and the Ni2Ce and Ni2Pr cases giving strongest evidence for exchange coupling.

A cobalt(II) coordination polymer, [Co(L1)(H2L2)]·2.5H2O, 1, has been prepared via the hydrothermal reaction of cobalt(II) chloride with the novel dicarboxy-Troger’s base ligand 2,8-dicarboxy-6H,12H-5,11-methano-dibenzo[b,f][1,5]diazocine, H2L1, and the bis-pyrazole ligand 4,4′-methylenebis-(3,5-dimethylpyrazole), H2L2. The structure of 1 contains 2D (4,4) networks showing 2D → 3D parallel interpenetration, whereby adjacent 2D sheets interlock through the apertures defined by the cleft-like Troger’s base ligand, to realise an overall 3D entanglement. The interlocking also forms one-dimensional solvent filled channels which are easily disturbed on drying resulting in framework collapse. The crystal structure of H2L1 is also reported, and represents a rare example of homochiral hydrogen bonded [6,4] dia networks interpenetrated by their enantiomeric partner frameworks.

The synthesis, structure and magnetic property of a new coordination network {[Co2(bcp)2(bpt)2]·2H2O}n (1) (H2bcp = 1,3-bis(4-carboxy-phenoxy)propane and bpt = 2,5-bis(4-pyridyl)-1,3,4-thiadiazole), is reported. Complex 1 shows a 3D 48.66.8 topology with unusual self-penetration, in which represents a new example of 6-connected networks. In addition, the magnetic property of 1 has also been investigated.

Four new dipyridylamino-substituted s-triazine ligands DBB (N(2),N(2),N(4),N(4)-tetrabenzyl-N(6),N(6)-di(pyridin-2-yl)-1,3,5-triazine-2,4,6-triamine), DDB (N(2),N(2),N(4),N(4)-tetrabutyl-N(6),N(6)-di(pyridin-2-yl)-1,3,5-triazine-2,4,6-triamine), DCCl (6-chloro-N(2),N(2)-dicyclohexyl-N(4),N(4)-di(pyridin-2-yl)-1,3,5-triazine-2,4-diamine) and DDT (N(2),N(2),N(4),N(4)-tetraphenyl-N(6),N(6)-di(pyridin-2-yl)-1,3,5-triazine-2,4,6-triamine), have been incorporated into eight new, 0D Fe(II) compounds of type [Fe(II)(NCX)(2)(L)(2)]·Solvent (where NCX = NCS(-), NCSe(-) or N(CN)(2)(-)). The polymorphic compounds α-trans-[Fe(II)(NCS)(2)(DBB)(2)] (1) and β-trans-[Fe(II)(NCS)(2)(DBB)(2)] (2) display, respectively, a relatively abrupt, complete, one-step spin transition with T(½) ~ 170 K, and a more gradual, complete, one-step spin transition with T(½) ~ 300 K. Gradual, one-step spin transitions are observed for trans-[Fe(II)(N(CN)(2))(2)(DBB)(2)]·2CH(3)CH(2)OH (3) and trans-[Fe(II)(NCSe)(2)(DCCl)(2)]·2CH(3)OH (6) with T(½) ~ 280 K for both, while the one-step spin transition observed for a desolvated sample of trans-[Fe(II)(NCSe)(2)(DDB)(2)]·2CH(3)OH (4) is relatively abrupt, showing hysteresis with T(½↑) = 285 K and T(½↓) = 275 K. The compounds cis-[Fe(II)(NCS)(2)(DDB)(2)] (5) and trans-[Fe(II)(NCS)(2)(DDT)(2)]·4CH(2)Cl(2) (7) remain high spin, while structural data on trans-[Fe(II)(NCSe)(2)(DDT)(2)]·4CH(2)Cl(2) (8) suggests a spin transition at low temperatures. It is likely that distortion of the Fe(II)N(6) octahedron, intermolecular interactions and molecular conformation are crucial in deciding both the T(½) and abruptness of the spin transition for these species, although the nature of their influence varies. Variable temperature powder X-ray diffraction measurements on the polymorphs 1 and 2 reveal anisotropy in the unit cell parameters as the spin transition occurs.

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.

International audience; A series of 1D polymeric FeII spin crossover (SCO) compounds of type trans-[FeII(NCX)2(L)]·Solvent has been synthesised {L = DPPyT = 1-[4,6-bis(dipyridin-2-ylamino)-1,3,5-triazin-2-yl]pyridin-4(1H)-one for 1–4; NCX = NCS– for 1 and 2, NCSe– for 3 and 4; Solvent = 2.5CH2Cl2 for 1, 2CHCl3·0.5CH3OH for 2 and 4, CH2Cl2 for 3; L = DPT (6-phenoxy-N2,N2,N4,N4-tetra-2-pyridinyl-1,3,5-triazine-2,4-diamine) for 5; NCX = NCS– for 5; Solvent = 2CH3OH·H2O for 5; L = DQT {4-[4,6-bis(dipyridin-2-ylamino)-1,3,5-triazin-2-yloxy]phenol} for 6–8; NCX– = NCS– for 6; Solvent = 2CH2Cl2 for 6; NCX– = NCSe– for 7; Solvent = CH2Cl2·CH2ClCH2Cl for 7; NCX– = NCSe– for 8; Solvent = 1.5CH2Cl2·0.5CH3OH for 8}. Two mononuclear complexes, trans-[FeII(NCS)2(DPT)2]·2CH3OH (9) and trans-[FeII(NCSe)2(DPT)2]·2CH3OH (10), contained the L ligand in a terminal bidentate coordination mode. As well as variations made in the NCX– ligands, variations were also made in substituent groups on the s-triazine “core” of L to investigate their intermolecular/supramolecular role in crystal packing and, thus, their influence on SCO properties. All the complexes crystallised as solvates, and the influence of the latter on the magnetism and spin transitions was explored. A wide range of physical methods was employed, as a function of temperature, viz. crystallography, PXRD (synchrotron), susceptibilities, LIESST and Mössbauer effect, in order to probe magnetostructural correlations in these 1D families. New examples of half-crossovers, with ordered –LS–HS–LS–HS– intrachain states existing below T1/2, have been observed and comparisons made to related one- or two-step systems. All the observed transitions are gradual and non-hysteretic, and brief comments are made in relation to recent theoretical models for cooperativity, developed elsewhere.

A fascinating 3D entangled metal-organic framework, namely, {[Co(2)(bcp)(2)]·3H(2)O}(n) (1), was obtained through the solvothermal generation of flexible and long dicarboxylate (bcp) and metal salt. The crystal structure contains a 1D metal chain with bcp ligands wrapped around it in a wavy line and features an unusual entangled topological net. Furthermore, the magnetic behavior of 1 was also studied and indicated the existence of ferromagnetic interaction and long-range ordering character.

The anionic dinitrile ligand dicyanonitrosomethanide (dcnm), C(CN) 2 (NO) - , and the anion resulting from its addition product with water, carbamoylcyanonitrosomethanide (ccnm), C(CN)(CONH 2 )(NO) - , have been incorporated into lanthanoid complexes and display unusual η 2 (N,O) nitroso coordination modes. (Et 4 N) 3 [Ln(ccnm) 6 ] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm) and (Me 4 N) 3 [Ln(ccnm) 6 ] (2Ln; 2Ln = 2La, 2Ce, 2Pr, 2Nd) are systems containing 12-coordinate homoleptic trianionic lanthanoidate complexes. The nitroso groups of the ccnm ligands form three-membered ring chelates with the lanthanoid metal centre, with the asymmetry of the nitroso η 2 interactions dependent upon the intramolecular N-H ··· O=N hydrogen bonding. Additional intermolecular hydrogen bonding interactions exist between adjacent amide and nitrile groups giving rise to 3D α-Po and 6,8-connected (4 12 .6 3 )(4 20 .6 8 ) networks in 1Ln and 2Ln, respectively. The compounds (Me 4 N) 3 [Ln(dcnm) 6 ] (3Ln; 3Ln = 3La, 3Ce, 3Nd, 3Sm) also contain a 12-coordinate trianionic lanthanoidate complex with the nitroso group exhibiting a highly symmetrical η 2 interaction. The sterically crowded environments of [Ln(18-crown-6)(dcnm) 3 ] (4Ln; 4Ln = 4La, 4Ce, 4Pr, 4Nd) result in a shift towards a more asymmetric η 2 bonding of the nitroso group with decrease in the Ln 3+ radius. There is a corresponding increase of the Ln-O-N angle, and one ligand is η 1 (O) binding in 4Nd. The dcnm ligands in the discrete complexes [La(phen) 3 (dcnm) (3-x) Cl x ], x ≈ 0.25 (5) (phen = 1,10-phenanthroline), (Et 4 N)[Ce(phen) 2 (dcnm) 4 ] (6a/ b, 6c) and [Ce(phen) 2 (dcnm)Cl 2 H 2 O] (7) display a variety of coordination modes. Complex 5 has 1D chains formed by π-π stacking of adjacent phen co-ligands. Complexes 6 contain the monoanionic complex [Ce(phen) 2 (dcnm) 4 ] - with two geometric isomers present in the crystal structure of 6a/b. Complex 7 forms extended 1D chains via hydrogen bonding between coordinated water and chloride atoms and an extensive array of face-to-face π interactions.

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} ...

The flexible ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazol-1-yl)ethane (L4Et) displays remarkable versatility in the complexes that it forms with transition metals with products ranging from 1D chains to interpenetrating 3D networks. The L4Et ligand itself crystallises in the space group P21, adopting a helical twist, although it is found in a variety of other conformations in its complexes. Coordination polymers containing the L4Et ligand vary from almost straight, parallel 1D chains of [Ag2(L4Et)2(ClO4)2(DMF)]·DMF (1), through interdigitating helical complexes containing tetrahedral Zn(II), [Zn(NCS)2(L4Et)]·DMF·H2O (2) to 2D sheets of [Cu(L4Et)2(H2O)2](PF6)2·xH2O (3) and the three-fold interpenetrating 3D network of [Co(L4Et)2(NCS)2] (4). The 3D network adopts an unusual 3D 4-connected dmp (65.8) topology. Dimensionality can be limited by the use of chelating co-ligands, demonstrated by the formation of the dinuclear complex [{Cu(py-2,6-CO2)(H2O)}2(L4Et)] (5).

Several new 1D coordination polymers have been synthesised using the anionic ligand carbamoyldicyanomethanide, C(CN)2(CONH2)− (cdm). The polymeric complexes [Cu(cdm)2(py)2]·2MeOH (1), [Cu(cdm)2(4-Etpy)2]·2MeOH (2), [Cu(cdm)2(3,5-Me2pzH)2]·2MeOH (3) and [Cu(cdm)2(3-HOCH2py)2]·2MeOH (4) (py = pyridine; 3,5-Me2pzH = 3,5-dimethylpyrazole) contain Cu(II) atoms bridged by μ2-(N,N′) cdm ligands between equatorial and axial coordination sites. The use of monodentate co-ligands brings about polymeric products, in contrast to the use previously of chelating co-ligands which facilitate the formation of discrete products. These 1D polymeric complexes are connected by hydrogen bonding between the amide functionalities and the lattice solvent. In the structures of 3 and 4 the neutral ligands also contain hydrogen bond donor groups that supplement the amide ring motif. Two other complexes have been obtained that are polymeric chains of alkoxide-bridged Cu(II) dimers. The complexes [Cu(cdm)(MeO)(2-amp)] (5) and [Cu(cdm)(dmap)] (6) (2-amp = 2-(aminomethyl)pyridine and dmap = dimethylaminopropoxide) are remarkably similar despite the different ligands that they contain. Bridging between dimers is via μ2-(N,O) cdm ligands, consequently altering the nature of the hydrogen bonding between adjacent chains compared to the simple polymeric species 1–3.

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.

Ligands resulting from the transition-metal-promoted nucleophilic addition of water or an alcohol to dicyanonitrosomethanide ions (dcnm) have been utilised in the formation of a large series of polynuclear complexes. Addition of water to dcnm results in formation of carbamoylcyanonitrosomethanide (ccnm); deprotonation of this ligand gives amidocarbonyl(cyano)nitrosomethanide (acnm), which has been incorporated into the trinuclear complex [Cu 3 (acnm) 2 (dmae) 2 (H 2 O) 2 ] [dmae = 2-(dimethylamino)ethoxide] (1) which shows strong antiferromagnetic coupling with an exchange coupling constant, J = ―500 cm ―1 . [Cu(acnm)(NH 3 ) 2 ] ∞ (2) marks the first instance of acnm facilitating the formation of a coordination polymer, namely a 1D chain with intramolecular hydrogen bonding. Attempts to synthesise 2 through different reaction conditions instead resulted in the mononuclear [Cu(acnm)-(NH 3 ) 2 (py)] (py = pyridine) (3). The addition of ethanol to dcnm results in cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) which features in the mononuclear [Cu(cenm) 2 -(H 2 O) 2 ] (4) and polymeric {[Cu(cenm) 2 ] 2 ·H 2 O} ∞ (5). The latter is the first example of the cenm ligand in a coordination polymer and has a highly unusual coordination mode through the nitrile groups and extremely weak antiferromagnetic coupling. {[Mn 3 (ccnm) 2 (EtOH) 2 (OAc) 4 ]·2EtOH} ∞ (6) and (Et 4 N) 2 -[Cu(ccnm) 4] (7) contain previously unobserved coordination modes of the ccnm ligand while the complex [Mn(cmnm) 3 -Mn(bipy)(MeOH)](ClO 4 ) (8) {cmnm=cyano[imino(methoxy)-methyl]nitrosomethanide, bipy = 2,2'-bipyridine} displays weak antiferromagnetic coupling between manganese atoms with J = ―1.44 cm ―1 . A change in the solvent systems used in the synthesis of 7 results in the formation of the mononuclear complexes [Mn(bipy) 2 (dcnm) 2 ] (9) or [Mn(bipy) 2 (H 2 O)-(dcnm)](dcnm)·H 2 O (10) and [Mn(bipy) 2 (dcnm)(H 2 0)](dcnm) (11). The addition of ethlyene glycol monomethyl ether to dcnm gives cyano[imino(2-methoxyethoxy)methyl]nitrosomethanide (cgnm) and the formation of [Cu(cgnm) 2 -(H 2 O) 2 ] (12).

A series of complexes of the form [M(Bp 3(4Bz) )(Tp 3(4Bz) )] containing a mixture of novel dihydrobis(3-(4-benzonitrile)pyrazolyl)borato (Bp 3(4Bz) ) and hydrotris(3-(4-benzonitrile)pyrazolyl)borato (Tp 3(4Bz) ) ligands have been synthesised and structurally characterised. The ligands, both containing 3-(4-benzonitrile)pyrazole arms, form isostructural complexes with a variety of transition metals although different crystalline solvates have been obtained depending upon the crystallisation conditions, namely [M(Bp 3(4Bz) )(Tp 3(4Bz) )] (M = Ni, Co), [Ni((Bp 3(4Bz) )(Tp 3(4Bz) )]·2MeOH and [M(Bp 3(4Bz) )(Tp 3(4Bz) )]·MeOH (M = Mn, Cd). In all cases the metal atoms are five-coordinate with an additional agostic B–H interaction from the bis(pyrazolyl)borate ligand.

Using Cu(II), Mn(II) or Co(II) salt and the flexible ligands, N-[(4-carboxyphenyl)-sulfonyl]glycine (H3L1) and N-[(3-carboxyphenyl)-sulfonyl]glycine (H3L2), a series of new coordination polymers, [Mn(phen)(H2O)4][HL1 ]( 1), [Co3(L1)2(bipy)3(H2O)6]n� 8nH2 O( 2), [Cu4(L1)2(OH)2(bipy)4]n� 12nH2 O( 3), [Na(H2L1)

The reaction of M(II) ions with azido ligands in the presence of different amino carboxylic acids gave four three-dimensional metal-azido coordination polymers, [Mn(3,5-daba)(N(3))](n) (1), [Cd(3,5-daba)(N(3))](n) (2; 3,5-daba = 3,5-diaminobenzoate), [Mn(4-aba)(N(3))](n) (3; 4-aba = 4-aminobenzoate), and [Cu(2)(gly)(2)(N(3))(2)](n) (4; gly = glycinate), which display different topological structures. Polymers 1 and 2 present 4,6-connected 3D networks with different Schlafli symbols. However, 3 and 4 feature an unprecedented trinodal 3,6-connected network with the Schlafli symbol (4(2).6)(4.6(2))(4(3).6(6).8(6)) and an unusual 4-connected 3D net with the Lonsdaleite (hexagonal diamond) topology, respectively. Magnetic susceptibility measurements revealed dominant antiferromagnetic couplings for 1 and 3 and an overall dominant ferromagnetic coupling for 4, which presents metamagnetic behavior with a magnetic phase transition at a critical temperature of 6 K and a transition field of ca. 6030 Oe. The results demonstrate that the EE azido and syn-anti carboxylato bridges in our cases induce an antiferomagnetic interaction, and the anti-anti carboxylato bridge in 4 mediates a ferromagnetic interaction. The magnetic interaction through the EO azido bridge in 3 and 4 has a dependence on the value of the M-N-M bond angle.

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...

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...

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.

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.

A series of interesting coordination polymers have been prepared by the combination of a V-shaped 4,4′-oxybis(benzoic acid) (H2oba) and neutral organonitrogen ligands with different metal ions, namely, {[M(oba)(bpe)]·H2O}n [M = Mn (1), Co (2)], [M(oba)(N3)]n [N3 = dipyridin-2-ylamine; M = Cd (3), Cu (4)] and {[Zn(oba)(N5)]·2H2O}n (5) [bpe = 1,2-bis(4-pyridyl)ethene, N5 = bis(pyridin-2-yl)pyridine-2,6-diamine]. The framework structures of these neutral polymeric complexes have been determined by single-crystal X-ray diffraction studies. Compound 1 has a threefold pcu-type network structure. Although 2 has the same ligands and coordination modes as 1, it consists of corrugated 2D layers formed of a series of squares, which allows the sheets to interpenetrate in an unusual 2D 3D parallel fashion. Polymers 3 and 4 exhibit double-helical chains formed by π–π stacking interactions from the phenyl rings of the N3 ligands. Compound 5 forms a 2D supramolecular architecture directed by hydrogen bonding between the NH groups of the N5 ligand, the uncoordinated carboxylate oxygens, and the intercalated water molecules. This work markedly indicates that the effect of auxiliary ligands is significant in the construction of these network structures, which are also well regulated by the metal centers. Thermogravimetric analysis (TGA) and XRPD results for compound 1 as well as luminescent properties for compounds 3 and 5 are discussed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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...

Four new compounds of partially or wholly deprotonated 5,5'-(1,4-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L1) and 5,5'-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L2), namely {[Co(L1)0.5] x (H2O)2}n (1), {[Mn(L1)0.5] x (H2O)2}n (2), {[Cu(H2L1)](mu2-bipy)}n (bipy = 4, 4'-bipyridyl) (3), and {[Zn2(L2)] x H2O}n (4) were synthesized in the presence or absence of auxiliary bipy ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Compounds 1 and 2 are isostructural and possess three-dimensional (3D) networks. In compound 3, multicarboxylate ligands and bipy ligands link Cu centers to generate a two-dimensional (2D) sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. In compound 4, the Zn centers are connected by L2(4-) anions to generate a 3D framework. Magnetic susceptibility measurements indicate that compounds 1 and 2 exhibit antiferromagnetic coupling between adjacent Co(II) ions and Mn(II) ions. The photoluminescent properties of the free 4L1 and H4L2 ligands and compound 4 have been studied in the solid state at room temperature. Both ligands and compound 4 exhibit strong violet emissions. Compared with the fluorescent emission of the ligand, the emission of 4 is red-shifted and enhanced.

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...

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 new Cd(II) complexes, having one binuclear structure [Cd2(L)2(Cl)2] (1) and another azido bridged one-dimensional zig-zag polynuclear network [Cd3(μ1,1-N3)4(L)2{H2N(CH2)2N(C2H5)2} · H2O]n (2) have been synthesized from a tridentate N2O donor Schiff base ligand LH, [LH = (OCH3)(OH)C6H3CHN(CH2)2N(C2H5)2], which is the condensation product of 2-hydroxy-4-methoxybenzaldehyde and 2-diethylaminoethylamine. Both the complexes 1 and 2 have been characterized by elemental analyses, IR & 1H NMR spectroscopy, TGA and fluorescence studies. Finally their structures have been established by single crystal X-ray diffraction method. Structural study reveals that in the complex 1, two Cd(II) centers are held together by two μ2-phenolato oxygen atoms and the terminal chlorine atom occupies the apical site of the square pyramidal environment of each metal center. In case of complex 2, the trinuclear asymmetric unit contains octahedral Cd(II) centers which are further held together by doubly end-on azido bridging to form a zig-zag polynuclear structure. It also displays intraligand 1(π–π∗) fluorescence and can potentially serve as photoactive material.

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).

Three lanthanide coordination polymers constructed from infinite rod-shaped secondary building units (SBUs), [Nd(2)(H(2)O)(2)(cis-chdc)(2)(trans-chdc)]2H(2)O (1), Nd(2)(H(2)O)(4)(trans-chdc)(3) (2), and [Sm(2)(H(2)O)(2)(cis-chdc)(trans-chdc)(2)]4H(2)O (3) (chdcH(2)=1,4-cyclohexanedicarboxylic acid), were hydrothermally synthesized and structurally characterized. The structures of 1-3 are modulated by different ratios of the cis and trans configurations of chdc(2-) ligands, which was achieved by temperature control in the hydrothermal reactions. Crystal-structure analysis revealed that 1 is a four-connected pcu-type rod packing network built from cross-linking of rod-shaped neodymium-oxygen SBUs by cis- and trans-chdc(2-) ligands in a 2:1 ratio, 2 displays a complicated six-connected hex-type rod packing structure built by connection of rod-shaped neodymium-oxygen SBUs and trans-chdc(2-) ligands, and 3 features an unprecedented five-connected rod packing pattern constructed from rod-shaped samarium-oxygen SBUs and cis- and trans-chdc(2-) ligands in a 1:2 ratio.

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...

The structure of tetramethylammonium hexanitratoneodymiate(III) has been determined at 123 K in the suprisingly low symmetry space group P 1 considering the simplicity of the compound. The structure has Z′ = 4 with seventeen distinct chemical fragments in the asymmetric unit (12 tetramethylammonium cations, three complete [Nd(NO3)6]3− anions and two half [Nd(NO3)6]3− species situated on special positions). This one structure contains five different coordination geometries of the [Nd(NO3)6]3− species.

An investigation into the dependence of coordination polymer architectures on organic-acid ligands is reported on the basis of the reaction of Pb(NO3)2 and eight structurally related organic-acid ligands in the presence or absence of N-donor chelating ligands. Eight novel lead(II)-organic architectures, [Pb(adip)(dpdp)]2 1, [Pb(glu)(dpdp)] 2, [Pb(suc)(dpdp)] 3, [Pb(fum)(dpdp)] . H2O 4, [Pb2(oba)(dpdp)2] . 2(dpdp).2(NO3).2H2O 5, [Pb2(1,4-bdc)2(dpdp)2] . H2O 6, [Pb(dpdc)(dpdp)] 7, and [Pb(1,3-bdc)(dpdp)] . H2O 8, where dpdp = dipyrido[3,2-a:2',3'-c]-phenazine, H2adip = adipic acid, H2glu = glutaric acid, H2suc = succinic acid, H2fum = fumaric acid, H2oba = 4,4'-oxybis(benzoic acid), 1,4-H2bdc = benzene-1,4-dicarboxylic acid, H2dpdc = 2,2'-diphenyldicarboxylic acid, and 1,3-H2bdc = benzene-1,3-dicarboxylic acid, were successfully synthesized under hydrothermal conditions through varying the organic-acid linkers and structurally characterized by X-ray crystallography. Compounds 1-8 crystallize in the presence of organic-acid linkers as well as secondary N-donor chelating ligands. Diverse structures were observed for these complexes. 1 and 5 have dinuclear structures, which are further stacked via strong pi-pi interactions to form 2D layers. 2-3 and 6-8 feature chain structures, which are connected by strong pi-pi interactions to result in 2D and 3D supramolecular architectures. Compound 4 contains 2D layers, which are further extended to a 3D structure by pi-pi interactions. A systematic structural comparison of these 8 complexes indicates that the organic-acid structures have essential roles in the framework formation of the Pb(II) complexes.

Four new coordination complexes, NiII(L)2 (1), [CoIII(L)2]ClO4 (2), [Zn(HL)(L)]ClO4 · H2O (3) and [Zn(L)2][Zn(L)(HL)]ClO4 · 7H2O (4) (where L is a monoanion of a Schiff base ligand, N′-[(2-pyridyl)methylene]salicyloylhydrazone (HL) with NNO tridentate donor set), have been synthesised and systematically characterised by elemental analysis, spectroscopic studies and room temperature magnetic susceptibility measurements. Single crystal X-ray diffraction analysis reveals that 1 is a neutral complex, while 2–4 are cationic complexes. Among them, 4 is a rare type of cationic complex with two molecules in the asymmetric unit. The ligand chelates the metal centre with two nitrogen atoms from the pyridine and imino moieties and one oxygen atom coming from its enolic counterpart. All the reported complexes show distorted octahedral geometry around the metal centres, with the two metal–N (imino) bonds being significantly shorter than the two metal–N (Py) bonds.