Double Zigzag Chains Research Articles

Coexistence of metamagnetism and single chain magnet behavior in a FeIII 2CoII layer compound

A cyanide-bridged FeIII 2CoII double zigzag chain, {[FeIII(bipy)(CN)4]2CoII(btab)2} n [bipy=2,2′-bipyridine, btab=4,4′-(1,3-phenylene)-bis-4H-1,2,4-triazole] (1), was obtained with tetracyanometalate precursors and CoII ions. The chains were further linked by the ditopic btab ligands to a layer. Magnetic property studies demonstrate that 1 shows both metamagnetism with a critical field H c=400 Oe and single-chain magnet behavior.

Crystal structures, thermal analysis and electrochemical behaviors of functionalized pyridinium ionic liquids comprising one 1-ethyl acetate group

Pyridinium ionic liquids(ILs, 1-ethyl acetate pyridinium hexfluorophosphate[EAPy][PF6] and 1-ethyl acetate-3-methyl pyridinium hexfluorophosphate[EAMPy][PF6]), were synthesized by a two-step process involving introduction of one ethyl acetate group and anion metathesis. Colorless single crystals of the two ILs were initially obtained using the solvent-evaporation method in mixed solvents. Single-crystal X-ray diffraction was used to determine the crystal structures. [EAPy][PF6] crystallize in the monoclinic space group C2/c with a=2.2748(16) nm, b=0.6204(4) nm, c=1.8552(12) nm and Z=8, whereas [EAMPy][PF6] crystallizes in the orthorhombic space group P212121 with a=0.7126(17) nm, b=1.2792(3) nm, c=1.5327(3) nm and Z=4. The structure of [EAPy][PF6] contains double zigzag chains formed by alternately pairing large organic cations with the octahedral anions of [P1F6]–or [P2F6]–. The [P1F6]– and [P2F6]– anions occupy respectively two distinct crystallographic sites in crystal packing models. The structure of [EAMPy][PF6] includes ladder-type chains constructed through pairing pyridinium cations with inorganic anions of [PF6]–. The [PF6]– anion in [EAMPy][PF6] shows a distorted octahedron structure and is sandwiched by ethyl acetate groups in crystallographic stacking. This study reveals the influence of chemical modification involving the methyl group(CH3) onto crystallographic structure of pyridinium ILs. Thermal analysis indicates that the difficult crystallization of the two ILs is related to the low void filling of ion pairs in crystal structure, leading to relatively low melting point and evident supercooling during the cooling process. Additionally, the experimental results indicate that the two ILs have electrochemical activity. The ethyl acetate group also allows downward shifting of electrochemical windows to less negative positions and the ionic conductivities of the two ILs follow an Arrhenius-type behavior.

Chiral solitons in a coupled double Peierls chain.

Chiral edge states are the hallmark of two- and three-dimensional topological materials, but their one-dimensional (1D) analog has not yet been found. We report that the 1D topological edge states, solitons, of the charge density wave system of indium atomic wires self-assembled on a silicon surface have chirality. The system is described by a coupled double Peierls-dimerized atomic chain, where the interchain coupling induces dynamical sublattice symmetry breaking. This changes its topological symmetry from Z₂× Z₂to Z₄ and endows solitons with a chiral degree of freedom. Chiral solitons can produce quantized charge transport across the chain that is topologically protected and controllable by the soliton's chirality. Individual right- and left-chiral solitons in indium wires are directly identified by scanning tunneling microscopy.

Structural study on four co-crystals of N-containing heteroaromatics with iodofluorobenzene

N-Containing heteroaromatics 1,2,4,5-tetra(pyridin-3-yl)benzene[1,2,4,5-T(3-PY)B] and 1,2,4,5-tetra-(pyridin-4-yl)benzene[1,2,4,5-T(4-PY)B] were each co-crystallized with 1,2-diiodo-tetrafluoro-benzene(1,2-DITFB), or 1,4-diiodo-tetrafluoro-benzene(1,4-DITFB), respectively, generating four co-crystals, namely, (1,2-DITFB)4·[1,2,4,5-T(3-PY)B](1), (1,2-DITFB)4·[1,2,4,5-T(4-PY)B](2), (1,4-DITFB)2·[1,2,4,5-T(3-PY)B]·CHCl3(3), and (1,4-DITFB)·[1,2,4,5-T(4-PY)B]·2CHCl3(4). This study takes aim at providing an insight into the relative importance of fundamental solid state halogen bonding interactions(i.e., halogen⋯N, halogen⋯halogen, and halogen⋯π) in systems. The effects of the donor and acceptor on supramolecular assembly and the crystal structure determined interactions were discussed. The N⋯I halogen bonds are the main directing interactions responsible for the observed structures. In compounds 1 and 2, the donors exhibited lower-than-expected supramolecular connectivity. In spite of this, co-crystal 2 exhibits polymeric structures consisting of infinite one-dimensional(1D) double-zigzag chains of alternating electron donor and acceptor. The basic structure of co-crystals 3 and 4 is also infinite 1D chain. Therefore, the 1D halogen bonded supramolecular assemblies can be obtained by matching the appropriate donor and acceptor.

1D Heterometallic Oxalate Compounds as Precursors for Mixed Ca–Cr Oxides – Synthesis, Structures, and Magnetic Studies

AbstractThe heterodimetallic compounds {[CaCr2(L)2(C2O4)4]·xH2O}n [L = 2,2′‐bipyridine (bpy), x = 0.83 (1); L = 1,10‐phenanthroline (phen), x = 0.33 (2)] were synthesized and characterized by IR spectroscopy, X‐ray diffraction and magnetic measurements. The crystal structure of 2 is reported: the chelation of a [Cr(phen)(C2O4)2]– units towards Ca cations results in 1D double zigzag chains. The ability of 1 and 2 to act as single‐source precursors for the formation of Ca–Cr oxides is explored by thermal analysis, powder X‐ray diffraction and IR spectroscopy. The thermal processing of 1 and 2 at 1100 °C in air led to the appearance of the β‐CaCr2O4 phase as the major crystalline oxide. By heating the samples up to 1100 °C in nitrogen, only the β‐CaCr2O4 phase formed, whereas heating at 1400 °C caused the crystallization of two polymorphs, α‐ and β‐CaCr2O4. The magnetic behaviour of β‐CaCr2O4 pointed to the freezing of magnetic moments in coexistence with a weak ferromagnetic order.

Cyano-bridged Fe2Cu double-zigzag chains: From metamagnetism to coexistence of metamagnetism and single-chain magnet behavior

It is a challenge to tune the magnetic properties of 1D complex via balancing the intra- and interchain magnetic interactions. Utilizing tricyanometalate precursors with different steric hindrance to react with CuII in the presence of 4-styrylpyridine or 4-cyanopyridine, respectively, two cyano-bridged {Fe2Cu} double-zigzag chains [FeIII(Tp)(CN)3]2CuII(4-styrylpyridine)2·3CH3CN·3H2O (Tp=hydrotris(pyrazolyl)borate) (1) and [FeIII(pzTp)(CN)3]2CuII(4-cyanopyridine)2·2CH3CN·H2O (pzTp=tetrakis(pyrazolyl)borate) (2) were obtained. 1 shows metamagnetism with a critical field of 700Oe, whereas 2 shows the coexistence of metamagnetism and single-chain magnet behavior.

From Oxalate-based Heterometallic Compounds to nanocrystalline Ca-Cr Oxides

"Metal-organic coordination systems may exert a variety of specific properties including porosity, conductivity, or luminescence and have potential applications in various fields, from heterogeneous catalysis to supramolecular magnetism. Recently, these systems are exploited as molecular precursors by thermal decomposition for the preparation of mixed-metal oxide [1-3]. Since this synthetic route is relatively new and unexplored, there are few reported examples of nanomaterials obtained in this way. The heterobimetallic polymeric compounds [CaCr2(bpy)2(C2O4)4]·0.83H2O}n (1) and {[CaCr2(phen)2(C2O4)4]·0.33H2O}n (2) (bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline) were synthesized and characterized. The crystal structure of 2 is reported: the [Cr(phen)(C2O4)2]– unit, through the two oxalate groups, acts as a chelating ligand towards Ca cations, resulting in one-dimensional (1D) double zigzag chains, formed of diamond-shaped units. The ability of compounds 1 and 2 to act as the single-source precursors for the formation of the CaII–CrIII oxides was explored by thermal analysis (TGA and DTA) in the stream of the synthethic air or nitrogen, powder X-ray diffraction and IR spectroscopy. The heat treatment of 1 and 2 resulted in the formation of mixed-metal oxide phases, CaCrO4, α-CaCr2O4 and β-CaCr2O4. Thermal processing of compounds at 11000C in the stream of air, led to the appearance of the orthorhombic β-CaCr2O4 phase as the major crystalline oxide, together with CaCrO4. By heating the samples up to 11000C in nitrogen flow, only β-CaCr2O4 phase was formed, whereas the heating at 14000C caused the crystallization of two polymorphs, α-CaCr2O4 and β-CaCr2O4. J.P. acknowledge financial help from the Croatian Academy of Sciences and Arts. This work has been supported by HAZU grant "XBroad – program za brzo i točno određivanje mikrostrukturnih parametara iz proširenja difrakcijskih linija polikristalnih uzoraka" and ""Nanokristalni oksidi prijelaznih metala: Mikrovalna sinteza i strukturna svojstva"""

Synthesis, crystal structures, and properties of two novel cadmium(II)–organic frameworks based on asymmetric dicarboxylate and N-donor ligands

Two novel cadmium(II)–organic frameworks with asymmetric dicarboxylate and N-donor ligands, namely [Cd(cpa)(phen)]n (1) and {[Cd2(cpa)2(bpy)1.5]·0.5H2O}n (2) (H2cpa=3-(4-benzoic)propionic acid, phen=1,10-phenanthroline, bpy=4,4′-bipyridine) have been hydrothermally synthesized and characterized by elemental analyses, FT-IR spectra, single-crystal X-ray diffraction analyses, TGA, powder XRD and fluorescent measurements. 1 displays a double zigzag chain structure containing 8-number and 22-number circles. 2 Shows a 6-connected 3D polymer network based on tetranuclear cadmium cluster units. The most striking feature of 2 is that a pair of identical 3D networks are interlocked with each other to the form a 2-fold interpenetrated 3D α-Po structural topology. The diverse structures of two complexes indicate that the skeleton of N-donor ligands plays a great role in the assembly of such different frameworks. In addition, the thermal stabilities, XRD and photoluminescence properties of 1–2 were also studied.

Proton-transfer supramolecular salts of d-/l-tartaric acid and 1-(2-Pyrimidyl)piperazine

Ionic supramolecular salts 1 and 2 were prepared by single-proton transfer reactions between 1-(2-pyrimidyl)piperazine and d-/l-tartaric acid. An interesting feature in the tartrate is the head-to-tail arrangement and very wide range of anionic substructures observed through hydrogen-bonding interactions, including ring motifs, infinite double zigzag chain and three-dimensional supramolecular framework. Thermal analysis revealed that salts 1 and 2 undergo an irreversible phase transition at about 158°C, which is ascribed to the loss of water molecule. The temperature- and frequency-dependent dielectric constants in 2 suggested a low-frequency thermal fluctuation above 100°C.

Two Cu(II) coordination polymers with single- and double-zigzag chains constructed from 4,4′-(dihydroxymethylene)dibenzoic acid

Two intriguing one-dimensional coordination polymers, [Cu2(dhmdb)2(H2O)2]⋅6H2O (1) and Cu(dhmdb)(1,10-phen) (2), have been hydrothermally synthesized and structurally characterized through exploring a new semi-rigid V-type dicarboxylate ligand with hydroxyl groups, 4,4′-(dihydroxymethylene)dibenzoic acid (H2dhmdb). Complexes 1 and 2 display double- and single-zigzag chain structures, respectively, which further result in two-dimensional supramolecular networks by O–H⋯O hydrogen-bonds and π⋯π stacking interactions. The network of 1 possesses one-dimensional rhombic channels along c axis with the size of about 8×8Å. The phase purity and thermal stability of 1 and 2 have also been investigated.

Characterization and Synthesis of Two New ZnII and CdII-Coordination Polymers Based on 3,3′-Biphenyl Dicarboxylate and N,N’-Donor Co-ligands

Two new 1D coordination polymers, [Zn(3,3′-bpdc)(2,2′-bpy)]n (1) and [Cd (3,3′-bpdc)(2,2′-bpy)]n (2) [3,3′-H2bpdc = 3,3′-biphenyl dicarboxylic acid, 2,2′-bpy = 2,2′-bi pyridine], were rationally designed and synthesized with an identical strategy that employed 3,3′-H2bpdc as a bridge and 2,2′-bpy as a terminal ligand. As expected, the 3,3′-bpdc2− anions bridge ZnII and CdII into a 1D zigzag single chain and 1D zigzag double chain, respectively. The 2,2′-bpy ligand serves as terminal components to decorate both sides of the 1D chain, which plays an important role in the self-assembly of the polymeric chain by providing potential supramolecular recognition sites for π–π stacking and C–H···π interactions. As a result, the two different zigzag chains in 1 and 2 are assembled into 2D wave-like layers via π–π stacking interactions. Furthermore, owing to the direction of the C–H···π interactions, the adjacent 2D layers embed into each other to form a 3D supramolecular framework. The thermogravimetric analysis and luminescent properties of 1 and 2 were also investigated. Two new 3D supramolecular embedded-frameworks based on 1D different-shaped coordination polymeric chains, have rationally synthesized and characterized. Moreover, the thermal stability and photoluminescence property of compounds 1 and 2 were also investigated.

Bounds on the Maximum Multiplicity of Some Common Geometric Graphs

We obtain new lower and upper bounds for the maximum multiplicity of some weighted and, respectively, nonweighted common geometric graphs drawn on $n$ points in the plane in general position (with no three points collinear): perfect matchings, spanning trees, spanning cycles (tours), and triangulations. (i) We present a new lower bound construction for the maximum number of triangulations a set of $n$ points in general position can have. In particular, we show that a generalized double chain formed by two almost convex chains admits $\Omega (8.65^n)$ different triangulations. This improves the bound $\Omega (8.48^n)$ achieved by the previous best construction, the double zig-zag chain studied by Aichholzer et al. (ii) We obtain a new lower bound of $\Omega(12.00^n)$ for the number of noncrossing spanning trees of the double chain composed of two convex chains. The previous bound, $\Omega(10.42^n)$, stood unchanged for more than 10 years. (iii) Using a recent upper bound of $30^n$ for the number of triangu...

Polyrotaxane frameworks containing N,N′,N′′-(4,4′,4′′-nitrilotris(4,1-phenylene))triisonicotinamide: structural and luminescent properties

The reaction of a C3-symmetric tridentate ligand, N,N′,N′′-(4,4′,4′′-nitrilotris(4,1-phenylene))triisonicotinamide (L), with various d10-metal salts of CuI, Cu(SCN), and M(ClO4)2 (M = Zn, Cd) led to four metal–organic materials of {[(Cu2I2)(L)2]·4DMF·2MeOH}n (1), {[Cu(L)2(NCS)2]·3DMF}n (2), and {[M(L)2(ClO4)2]·4EtOH}n (M = Zn 3 and Cd 4), respectively, which have been isolated and structurally characterized by X-ray diffraction studies. The X-ray analysis revealed that the interlocking of the 1-D double-zigzag chains of 1–4 into the macrocycles of the adjacent chains generates a novel 2-D (1-D → 2-D) polyrotaxane framework. In these 2-D polyrotaxane frameworks, the C3-symmetric tridentate ligand, L, only adopts a μ2-bridging mode, and the third arm is free. In addition, 1–4 are all emissive with dual emissions (431–452 and 558–570 nm) in the solid state at room temperature and at 77 K, which are suggested to be due to an intraligand transition of L based on the high similarities in emission energies to that of L.

Two solvent directed zinc(II) coordination polymers with 1-D single-zigzag chain and 1-D double-zigzag chains

Two coordination polymers, {[Zn(NiL)(DMA)(H2O)2] (DMA)(H2O)} n (1) (DMA = N,N-dimethylacetamide) and {[Zn2(NiL)2(DMF)(H2O)4] · 3DMF} n (2) (DMF = N,N-dimethylformamide), have been prepared by reactions of Zn(NO3)2 · 6H2O and NiL in CH2Cl2-DMA–H2O and CH2Cl2-DMF–H2O, respectively. H2L denotes dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo-9,10-benzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Single-crystal X-ray diffraction analyses reveal that coordination geometries around Ni(II) are identical with slightly distorted square planar and all Ni–N bonds are very short. Complex 1 shows 1-D zigzag chain structure, while 2 has 1-D double-zigzag chains. The chains, which are packed parallel in 1 and 2, are interconnected by lattice solvent through O–H···O and C–H···O hydrogen bonds to form 3-D supramolecular networks. We discuss solvent effects on assembly of the two coordination polymers. The results reveal that coordinated solvent has influence on the assembly procedure.

(3-Chloropropyl)triphenylphosphonium bromide

The title compound, C21H21ClP+Br−, is the bromide salt of a mixed aryl-alkyl phospho­nium cation. C–P–C angles span a range of 107.20 (10)–111.18 (10)°. The non-H atoms of the 3-chloro­propyl group adopt a staggered conformation [C–C–C–Cl torsion angle: −72.0 (3)°]. In the crystal, C—H⋯Br contacts connect the entities of the title compound into a double zigzag chain along b. These chains are linked into a supra­molecular layer lying parallel to (10-1) by C—H⋯π inter­actions.

Hydrothermal Synthesis, Structure, Magnetic, and Photoluminescent Properties of a Heterometallic Cobalt(II)/Cerium(III) Coordination Compound with the Ligand Pyrazine 2, 3‐di­carboxylic Acid

AbstractHydrothermal reaction of the metalloligand {[Co(Pzdc)2]·2H2O}n (1) with Ce(NO3)3·6H2O yields a heterometallic 3d‐4f coordination compound {[Ce2Co(Pzdc)4(H2O)6]·2H2O}n (2) (H2Pzdc = pyrazine 2, 3‐dicarboxylic acid). X‐ray structure determination, IR spectroscopy, elemental analysis, thermogravimetric analysis, and magnetic property for the targets are presented. Compound 1 affords one‐dimensional double zigzag chains. Compound 2 features a three‐dimensional CoII–CeIII herringbone structure, in which the slightly deformational 1 and central CeIII atoms are linked by Pzdc2– spacers, and is further analyzed with {4.62}2{42.62.82}{63}2{65.8}2 topology symbol. Magnetic property analysis reveals that the antiferromagnetic interactions occur in compound 2 due to a long‐range superexchange pathway between adjacent magnetic centers. In addition, the solid state photoluminescence of 2 was investigated.

Synthesis, structure, and magnetic properties of a cyanide-bridged Fe(Ⅲ)-Cu(Ⅱ) bimetallic double-zigzag chain with slow relaxation of the magnetization

Synthesis, structure, and magnetic properties of a cyanide-bridged Fe(Ⅲ)-Cu(Ⅱ) bimetallic double-zigzag chain with slow relaxation of the magnetization

Chiral cyanide-bridged 1D FeIII-MnIII heterobimetallic chains: Synthesis, structures and magnetic properties

Two couples of enantiomerically pure chiral cyano-bridged heterobimetallic one-dimensional (1D) chain complexes: [Mn(( R , R )-Salphen)Fe(Tp)(CN) 3 ] n ( 1 ) and [Mn(( S , S )-Salphen)Te(Tp)(CN) 3 ] n ( 2 ) (Salphen = N , N '-1,2- diphenyl ethylenebis (salicylideneiminato) dianion, Tp = tris(pyrazolyl) hydroborate), [Mn(( R , R )-Salphen)Fe(Tp*) (CN) 3 ·2H 2 O] n ( 3 ) and [Mn(( S , S )-Salphen)Fe(Tp*)(CN) 3 ·2H 2 O] n (4) (Tp* = hydridotris (3,5-dimethylpyrazol- 1-yl) borate), have been successfully synthesized by the reactions of Mn Ⅲ schiff-base complexes with the tricyanometalate building block, [(L Tp )Fe(CN) 3 ] - (L Tp = Tp or Tp*). All complexes are made up of neutral cyano-bridged zigzag double chains with (-Fe-C≡N-Mn-N≡C-) n as the repeating unit. Circular dichroism (CD) spectra confirm the enantiomeric nature of the optically active complexes. Magnetic studies demonstrate that ferromagnetic interactions are operative in these complexes. The ferromagnetic couplings become weak in the chains with the bending of the Mn-N≡C angles.

Synthesis, structure, and magnetic properties of a cyanidebridged Fe(III)-Cu(II) bimetallic double-zigzag chain with slow relaxation of the magnetization

Using Bu4N[Fe(Tp*)(CN)3]− (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) as the building block to react with CuII and N-methylimidazole, we obtained a one-dimensional (1D) heterobimetallic cyano-bridged chain, [Fe(Tp*)(CN)3]2Cu(N-methylimidazole)2·2H2O (1). The crystal structures and magnetic studies demonstrate that complex 1 exhibits slow relaxation of the magnetization due to strong intrachain ferromagnetic coupling and weak interchain interactions.

Chiral Cyanide-Bridged CrIII–MnIII Heterobimetallic Chains Based on [(Tp)Cr(CN)3]−: Synthesis, Structures, and Magnetic Properties

By the reactions of Mn(III) Schiff-base complexes with the tricyanometalate building block, [(Tp)Cr(CN)(3)](-) (Tp = Tris(pyrazolyl) hydroborate), two couples of enantiomerically pure chiral cyano-bridged heterobimetallic one-dimensional (1D) chain complexes, [Mn((R,R)-Salcy)Cr(Tp)(CN)(3)·1/4H(2)O·1/2CH(2)Cl(2)](n) (1) and [Mn((S,S)-Salcy)Cr(Tp)(CN)(3)·1/4H(2)O·1/2CH(2)Cl(2)](n) (2) (Salcy = N,N'-(1,2-cyclohexanediylethylene)bis(salicylideneiminato) dianion), [Mn((R,R)-Salphen)Cr(Tp)(CN)(3)](n) (3) and [Mn((S,S)-Salphen)Cr(Tp)(CN)(3)](n) (4) (Salphen = N,N'-1,2-diphenylethylene-bis(salicylideneiminato) dianion), have been successfully synthesized. Circular dichroism (CD) spectra confirm the enantiomeric nature of the optically active complexes. Structural analyses reveal the formation of neutral cyano-bridged zigzag single chains in 1 and 2, and neutral cyano-bridged zigzag double chains in 3 and 4. Magnetic studies show that antiferromagnetic couplings are operative between Cr(III) and Mn(III) centers bridged by cyanide. Complexes 1 and 2 are the rare examples of chiral ferrimagnets; while complexes 3 and 4 exhibit a coexistence of chirality and spin-glass behavior in a 1D chain.