Synthesis and Characterization of Heterobimetallic Zigzag Chains with a Close-packed Structure Based on Macrocyclic Metalloligands

Two new heterobimetallic coordination polymers{[Co(NiL)(H2O)3]·4H2O}n(1)and{[Cu(NiL)(H2O)3]·4H2O}n(2)were synthesized based on metalloligand under the same self-assembly conditions.X-ray diffraction analyses reveal that the two compounds involve close-packed zigzag chains,which expand into various three-dimensional supramolecular frameworks through the second interactions such as hydrogen bonds andπ···πstacking interactions.In these two compounds,NiL as a bridging ligand chelates the metal ion nodes via two oxamido carbonyls and carboxylate oxygen atom.The central Co(Ⅱ)and Cu(Ⅱ)ions in 1 and 2 both exhibit distorted octahedral coordination geometry.They are bridged by macrocyclic oxamido metalloligands fusing the zigzag chains with a‘‘head-to-tail’’arrangement.The Ni(Ⅱ)ion in metalloligand is coordinated by four nitrogen atoms with the[NiN4]chromophore exhibiting distorted planarity.The two investigated compounds were further characterized by thermogravimetric analysis and FT-IR spectroscopy.The fluorescent properties of 1 and 2 in the solid state were also investigated.

Design,Synthesis and Crystal Structure of Two One-dimensional Zigzag Chain-like Compounds

Two one-dimensional chain-like cyanide-bridged compounds, [Fe（Phen）2（CN）2Ni（Cyclam）]（ClO4）2·DMF-2H2O 1 （Cyclam = 1,4,8,11-tetraaza-cyclotetradecane, Phen = 1,10-phenanthroline, and DMF = N,N-dimethylformamide） and [Fe（Phen）2（CN）2Zn（Cyclam）]（PF6）2·CH3CN 2, were prepared by the reaction of [Fe（Phen）2（CN）2]·2H2O with M（Cyclam）^2＋ （M = Ni, Zn）. In complexes 1 and 2, the metal atoms are connected alternatively with CN groups. X-ray structure and IR analyses for 1 and 2 were performed. Structure analysis revealed that both complexes are centrosymmetric and the geometry around each metal atom is an octahedron. The two complexes crystallize in triclinic with space group of P^1-. For 1, a = 10.439（4）, b = 14.976（7）, c = 15.914（8）A,α = 83.168（15）, β = 74.338（15）, γ = 78.023（15）°, V = 2338.3（18）A^3, Z = 2, Mr = 1035.37, Dc = 1.471 g/cm^3, F（000） = 1076,μ = 0.895 mm^-1, the final R = 0.0616 and wR = 0.1414 for 5849 observed reflections （1 〉 2σ（I））. For 2, a = 9.656（6）, b = 15.404（9）, c = 15.822（10）A, α = 78.68（2）, β= 78.917（19）, γ = 77.15（2）°, V = 2223（2）A^3, Z = 2, Mr = 1064.87, Dc = 1.587 g/cm^3, F（000） = 1078,μ = 1.032 mm^-1, the final R = 0.0672 and wR = 0.1595 for 6819 observed reflections （I 〉 2σ（I））.

Ferrimagnetism induced by asymmetrical ferromagnetic next-nearest-neighbour exchange interactions in an antiferromagnetic spin-1/2 zigzag chain

The magnetic properties of an antiferromagnetic bond alternating spin-l/2 zigzag chain with asymmetrical ferro- magnetic next-nearest-neighbour exchange interactions at finite temperature are investigated by using the many-body Green＇s function theory. It is found that the ferrimagnetic ordering does not appear in the symmetrical next-nearest- neighbour coupling case, and takes place only for the asymmetrical next-nearest-neighbour case at finite temperature rather than the ground state. Furthermore, as the asymmetry degree of the next-nearest-neighbour exchange inter- actions increases, the ferrimagnetism becomes more and more dominant. It is shown that the elementary excitation spectra are responsible for the observed magnetic behaviour.

Syntheses and Crystal Structures of Two Co(II) Coordination Polymers with 4,4'-(Hexafluoroisopropylidene)bis(benzoic acid)

Two new one-dimensional zigzag chain coordination polymers, [Co（hfipbb）（2,2＇- bpy）（H2O）2]n 1 and [Co（hfipbb）（1,10-phen）（H2O）], 2, have been synthesized under hydrother- mal reactions from COCl2.6H20, 4,4＇-（hexafluoroisopropylidene）bis（benzoic acid） and 2,2＇ -bipyridine or 1,10-phenanthroline ligands, respectively. Single-crystal X-ray analyses revealed that the zigzag chains of 1 and 2 are linked into three-dimensional supramolecular networks by both O-H…O hydrogen-bonds and π…π stacking interactions. Crystal data for 1： CzTHajCoF6N2Os Mr = 641.38, orthorhombic, space group Pnna, a = 9.3820（19）, b = 27.366（6）, c = 10.106（2）A, V = 2594.8（9）A3, Z = 4, Dc = 1.642 g/cm3, F（000） = 1300,/t = 0.752 mm-l, R = 0.0311 and wR = 0.0924. Crystal data for 2： C29H18CoF6N2O5, Mr = 647.38, monoclinic, space group P21/n, a = 7.7626（16）, b = 29.446（6）, c = 11.281（2）A,β= 93.98（3）°, V= 2572.3（9）A3, Z = 4, Dc = 1.672 g/cm3, F（000） = 1308,μ= 0.757 mm-1, R = 0.0403 and wR = 0.0820.

Syntheses and Crystal Structures of Two One-dimensional Coordination Polymers Constructed from a Flexible Hinge-like Ligand

By using the flexible hinge-like ligand 2,2＇-bis（3-hydroxy-l,4-naphthoquinone） （H2bhnq）, two isomorphous one-dimensional zigzag chain coordination polymers have been obtained. Single-crystal X-ray analyses revealed that the metal centers in these two complexes are distorted octahedra involving four oxygen atoms of two bhnq2 anions, and two oxygen atoms of two DMF molecules situated in trans positions to one another. Crystal data for [Mn（bhnq）（DMF）2]n 1： C26H22MnN2O8, Mr = 545.40, monoclinic, space group C2/c, a = 14.936（3）, b = 10.362（2）, c = 15.901（3）A., β = 99.86（3）°, V = 2424.7（8）A3, Z = 4, Dc = 1.494 g/cm^3, F（000） = 1124,μ = 0.599 mm^-1, final GOOF = 1.025, R = 0.0654 and wR = 0.1537. Crystal data for [Cd（bhnq）（DMF）2]n 2： C26H22CdN2O8, Mr = 602.86, monoclinic, space group C2/c, a = 14.839（3）, b = 10.493（2）, c = 16.034（3）A, β = 99.40（3）°, V = 2463.1（9）A^3, Z = 4, Dc = 1.626 g/cm^3, F（000） = 1216,μ = 0.941 mm^-1, final GOOF = 1.069, R = 0.0358 and wR = 0.0944.

Syntheses and Crystal Structures of Two Zn(Ⅱ) Coordination Polymers Constructed with 4,4'-(Dihydroxymethylene)dibenzoic Acid

Two new isomorphous metal-organic coordination polymers, [Zn（dhmdb）（2,2＇- bpy）]n 1 and [Zn（dhmdb）（1,10-phen）]n 2, have been obtained under hydrothermal reactions from 4,4＇-（dihydroxymethylene）dibenzoic acid （H2dhmdb）, Zn（NO3）2·6H2O and 2,2＇-pyridine or 1,10- phenanthroline, respectively. Compounds 1 and 2 have been characterized by FT-IR spectroscopy, thermal analysis and single-crystal X-ray diffraction. The zigzag chains of 1 and 2 are linked into three-dimensional supramolecular networks by both O–H…O hydrogen bonds and π…π stacking interactions. Crystal data for 1： ZnC25H18N2O6, Mr = 507.78, orthorhombic, space group Pbca, a = 14.031（3）, b = 10.826（2）, c = 27.343（6）, V = 4153.5（14）3, Z = 8, Dc = 1.624 g/cm3, F（000） = 2080, μ = 1.231 mm-1, R = 0.0699 and wR = 0.1829. Crystal data for 2： ZnC27H18N2O6, Mr = 531.80, orthorhombic, space group Pbca, a = 13.796（3）, b = 10.809（2）, c = 28.612（6）, V = 4266.8（15）3, Z = 8, Dc = 1.656 g/cm3, F（000） = 2176, μ = 1.203 mm-1, R = 0.0454 and wR = 0.1399.

Synthesis and Structure of a Zinc(II) Complex:[Zn(Pybta)·Cl_2]_n

The title compound, [Zn（Pybta）Cl2]n （Pybta = 1-（2-pyridylmethyl）benzontriazole）, has a zigzag chain structure. It crystallizes in the monoclinic system, space group P21/c with a = 9.0103（11）, b = 17.0276（18）, c = 9.2288（11）A,β = 101.309（6）°, Mr= 346.51, V= 1388.4（3）A^3, Z= 4, De= 1.658 g/cm^3, F（000） = 696,/a = 2.143 mm^-1, the final R = 0.0492 and wR = 0.1236 for 2545 observed reflections with I 〉 2σ（I）. The Zn atom is four-coordinated by two N and two Cl atoms, forming a slightly distorted tetrahedral geometry. Each zigzag chain links its adjacent symmetryrelated equivalents via multiple π-π interactions, which are not frequently observed in the previously reported architectures.

Structure dependent elastic properties of supergraphene

Complete replacement of aromatic carbon bonds in graphene by carbyne chains gives rise to supergraphene whose mechanical properties are expected to depend on its structure. However, this dependence is to date unclear. In this paper, explicit expressions for the in-plane stiffness and Poisson＇s ratio of supergraphene are obtained using a molecular mechanics model. The theoretical results show that the in-plane stiffness of supergraphene is drastically（at least one order） smaller than that of graphene, whereas its Poisson＇s ratio is higher than 0.5. As the index number increases（i.e., the length of carbyne chains increases and the bond density decreases）, the in-plane stiffness of supergraphene decreases while the Poisson＇s ratio increases. By analyzing the relation among the layer modulus, in-plane stiffness and Poisson＇s ratio, it is revealed that the mechanism of the faster decrease in the in-plane stiffness than the bond density is due to the increase of Poisson＇s ratio. These findings are useful for future applications of supergraphene in nanomechanical systems.

A New Zn(Ⅱ) Coordination Polymer Constructed by 1,4-Benzenedithiolate Dianion: [Zn(SC_6H_4S)(1,3-DPA)]_n

A new one-dimensional polymer, [Zn（SC6H4S）（1,3-DPA）]n （1, SC6H4S = 1,4-ben- zenedithiolate and 1,3-DPA = 1,3-diaminepropane）, has been synthesized and characterized by elemental analysis, PXRD, IR spectra, and single-crystal X-ray diffraction. The complex crystallizes in triclinic system, space group P1, with a = 6.7119（1）, b = 9.0230（2）, c = 10.4943（2） A, a = 69.288（1）, β = 75.848（1）, ）, = 81.513（1）°, V= 575.123（19） A3, Dc = 1.615 g/cm^3, Z = 2, F（000） = 288; the final S = 1.070, R = 0.0234, and wR = 0.0551. The compound consists of an infinite zigzag chain formed by [Zn（1,3-DPA）]^2＋ units joined by SC6H4S ligands. Each chain interacts with neighboring chains via weak N-H…S hydrogen bonds to form an extended three-dimensional （3D） supramolecular network. The thermal and photoluminescent properties of 1 have also been investigated.

Structure and magnetic properties of the S=3/2 zigzag spin chain antiferromagnet BaCoTe_(2)O_(7)

We report a study of the structure and magnetic properties of the S=3/2 zigzag spin chain compound BaCoTe_(2)O_(7).Neutron diffraction measurements show that it crystallizes in the noncentrosymmetric space group Ama2 with a canted↑↑↓↓spin structure along the quasi-one-dimensional zigzag chain and a moment size of 1.89(2)μBat 2 K.Both magnetic susceptibility and specific heat measurements yield an antiferromagnetic phase transition at TN=6.2 K.A negative Curie-Weiss temperature,ΘCW=-74.7(2) K,and an empirical frustration parameter,f=|ΘCW|/TN≈12,are obtained by fitting the magnetic susceptibility,indicating antiferromagnetic interactions and strong magnetic frustration.From ultraviolet-visible absorption spectroscopy and first-principles calculations,an indirect band gap of 2.68(2) eV is determined.We propose that the canted zigzag spin chain of BaCoTe_(2)O_(7) may produce a change in the polarization via the exchange-striction mechanism.