Infinite Zigzag Chain Structure Research Articles

Five organotin complexes derived from hydroxycinnamic acid ligands: Synthesis, structure, in vitro cytostatic activity and binding interaction with BSA

Five new organotin(IV) hydroxycinnamates, [(Me3Sn)HL1]n (1), [(Ph3Sn)2L1]n (2), (n-Bu2Sn)(HL1)2 (3), [(Me3Sn)HL2]n (4), [(Ph3Sn)2L2]n (5), have been synthesized by the reactions of R3SnCl (R = Me, Ph) or n-Bu2SnO with the corresponding hydroxycinnamic acid proligands [H2L1 = 4-OH-3-CH3OC6H3CH=CHCOOH, ferulic acid; H2L2 = 4-OH-3,5-(CH3O)2C6H2CH=CHCOOH, sinapic acid]. All the complexes have been characterized by X-ray diffraction analysis, elemental analysis, NMR (1H, 13C and 119Sn), FT-IR, and PXRD (Powder X-ray diffraction). The structural analyses reveal that complexes 1, 2 and 5 display 1D infinite zig-zag chain structure, in which the 1D chains are further linked into a 3D supramolecular structure through intermolecular O-H···O interactions (for complex 1) or C-H···O interactions (for complex 5). Complex 3 presents mononuclear tin monomer and further constructs 2D planar supramolecular structure through intermolecular O-H···O interactions. Complex 4 displays 1D right-handed helical chain and further connects into a 3D supramolecular architecture through intermolecular O-H···O interactions. Furthermore, the in vitro cytostatic activity of complexes 1-5 was preliminarily evaluated by MTT method, and the results showed that complexes 2, 3 and 5 exhibited high cytostatic activity. The protein-binding properties of complexes 2, 3 and 5 were also investigated, which indicated these complexes could quench the intrinsic fluorescence of BSA in a static way.

Novel triorganotin complexes based on phosphonic acid ligands: Syntheses, structures and in vitro cytostatic activity

Six novel organotin phosphonate complexes, [(Me3Sn)4(HL1)4]n1, [(Me3Sn)2(HL2)2]n2, [(Me3Sn)2L3(H2O)]n3, [(Ph3Sn)(HL1)]64, [(Ph3Sn)2L2]n5 and [(Ph3Sn)2L3]66, derived from phosphonic acid ligands [NaHL1 = 1-C10H7OPO2(OH)Na, H2L2 = 1-C10H7PO(OH)2, H2L3 = 2-C10H7PO(OH)2], have been synthesized and characterized by elemental analysis, FT-IR, NMR (1H, 13C, 31P and 119Sn) spectroscopy and X-ray crystallography. The structural analysis reveals that complexes 1 and 5 display 1D infinite zig-zag chain structures, and complex 2 shows 1D right-handed helical chain structure, while complex 3 displays 1D left-handed helical chain structure. Complexes 4 and 6 are 24-membered macrocyclic rings interconnected by P, O and Sn atoms. Additionally, the molecules of complexes 1 and 3 are further linked through intermolecular π···π and O-H···O interaction into supramolecular structures, respectively. Furthermore, we preliminarily estimated in vitro cytostatic activity of complexes 1–6 against the human cervix tumor cells (HeLa), human hepatocellular carcinoma cells (HepG-2) and human normal breast cells (HBL-100). Importantly, the anti-proliferative properties and possible pathway of complex 6 are investigated, and the results demonstrate that complex 6 could induce apoptotic cell death via an overload of intracellular reactive oxygen species (ROS) levels and the dysfunctional depolarization of mitochondrial membranes.

Syntheses, structures and in vitro cytostatic activity of four novel homochiral organotin(IV) phosphonates

Four novel homochiral organotin phosphonates, namely, (R)-, (S)-[(Me3Sn)2(pemp)(H2O)]n (1, 2) and (R) -, (S)-[(Ph3Sn)2(pemp)2]n (3, 4) [pempH2 = (R)- or (S)-(1-phenylethylamino) methylphosphonic acid], were synthesized and characterized by X-ray diffraction analysis, elemental analysis, FT-IR, NMR (1H, 13C, 31P and 119Sn), TGA (thermogravimetric analysis) and CD (circular dichroism spectra). The structure analysis indicates that complex 1 displays 1D left-handed helical chain and complex 2 shows right-handed helical chain. These 1D chains are further linked into a 2D supramolecular network architecture through the intermolecular O–H⋯O interactions. Complexes 3 and 4 are isostructural that showing 1D infinite zig-zag chain structure. In addition, the molecules of complexes 3 and 4 are further linked through intermolecular C–H···π interactions into a 2D supramolecular structure. Furthermore, we preliminarily estimated in vitro cytostatic activity of complexes 1–4 against the human cervix tumor cells (HeLa) and the human hepatocellular carcinoma cells (HepG-2).

Crystal structure of a new mixed-metal coordin-ation polymer consisting of NiII piperidine-di-thio-carbamate and penta-nuclear CuI-I cluster units.

A new heterometallic CuI-NiII coordination polymer, poly[[tetra-μ3-iodido-μ2-iodido-bis-(μ3-piperidine-1-di-thio-carbamato)propio-nitrilepenta-copper(I)nickel(II)] chloro-form monosolvate], {[CuI5NiIII5(C6H10NS2)2(C3H5N)]·CHCl3} n , has been synthesized and structurally characterized. This coordination polymer consists of an NiII mononuclear unit of NiII(Pip-dtc)2 (Pip-dtc- is piperidine-1-di-thio-carbamate) and a penta-nuclear copper(I) cluster unit of Cu5I5(CH3CH2CN). The NiII ion, which lies on an inversion centre, is surrounded by four S atoms in a square-planar coordination geometry while all CuI ions have distorted tetra-hedral coordination geometries. In the penta-nuclear copper(I) cluster unit, a mirror plane passes through one CuI ion and three I ions. All the S atoms in NiII(Pip-dtc) are also coordinated by the CuI ions, forming an infinite zigzag chain structure along the b-axis direction. The chains are weakly connected by solvent CHCl3 mol-ecules via Cl⋯I [3.653 (1) Å] and Cl⋯S [3.4370 (1) Å] short-contact inter-actions.

Seven copper (I) complexes of diphosphine ligands and N^N ligands: Syntheses, structural characterizations and spectroscopic properties

The reactions of diphosphine ligands and nitrogen-containing ligands with Cu(I) salts in the mixed solvents of methanol (MeOH) and dichloromethane (CH2Cl2) generated the corresponding complexes, {[Cu(dppbe)(Bphen)](ClO4)·2CH3OH}n (1), {[Cu2(dppe)(dmp)2(CN)2]·2CH3OH}n (2), {[Cu2(dppb)(dmp)2I2]·2CH3OH}n (3), [Cu(POP)(C16H6N6)]I (4), {[Cu(POP)(C16H6N6)](SCN)}n (5), [Cu(xantphos)(bpy)](ClO4) (6) and {[Cu(xantphos)(bpy)](CF3SO3)}n (7) {dppbe=1,2-bis(diphenylphosphanyl)benzene, dppe=1,2-bis(diphenylphosphino)ethane; dppb=1,4-bis(diphenylphosphino)butane, POP=bis[2-(diphenylphosphino)phenyl]ether, xantphos=4,5-bis (diphenylphosphio)-9,9-dimethylxanthene, Bphen=4,7-diphenyl-1,10-phenanthroline, dmp=2,9-dimethyl-1,10-phenanthroline, C16H6N6=[2,3-f]-pyrazino-[1,10]phenanthroline-2,3-dicarbonitrile, bpy=2,2′-bipyridine}. These complexes were all characterized by single-crystal X-ray crystallography, elemental analysis, IR, 1H NMR spectroscopy, luminescence and THz spectroscopy. Complexes 1 and 2 consist of 1D infinite zigzag chain structures which are linked by hydrogen bonds, while complexes 3, 5 and 7 have 2D topological architectures which are connected by hydrogen bonds, complex 4 has an annular structure and complex 6 is a mononuclear structure. The types of hydrogen bonds, choice of solvents and coordination modes of the ligands are of importance in defining the structural and topological features of the resulting networks. Furthermore, complexes 1–7 exhibit interesting luminescence in the solid state at room temperature. Complexes 1–3 can act as yellow luminophores, complex 4 acts as a red luminophore, complex 5 acts as an orange luminophore and complexes 6–7 act as green luminophores. Their terahertz spectra show more accurate characteristics of their structures.

Syntheses, structural characterizations and terahertz spectra of Ag(I)/Cu(I) complexes with bis[2-(diphenylphosphino)phenyl]ether and N^N ligands

Five novel silver(I) complexes and two copper(I) phosphine complexes containing the bis[2-(diphenylphosphino)phenyl]ether ligand were synthesized and structurally characterized. Treatment of AgX/CuX and the bis[2-(diphenylphosphino)phenyl]ether with N^N ligands afforded the silver(I) or copper(I) complexes {[Ag2(POP)2(dpa)(H2O)2](dpa)(ClO4)2}n (1), {[Ag(POP)(dpp)](ClO4)}n (2), [Ag2(POP)2(4,4′-bipy)(CH3CN)2](CF3SO3)2·CH3CN (3), {[Ag(POP)(dpe)](CF3SO3)·CH3CN}n (4), {[Ag2(POP)2(dpe)(H2O)2](dpe)(BF4)2}n (5), [Cu(POP)(bpy)](BF4) (6) and [Cu2(POP)2(4,4′-bipy)](CF3SO3)2·4CH3CN (7) {POP=bis[2-(diphenylphosphino)phenyl]ether; dpp=1,3-bis(4-pyridyl)propane; dpa=1,2-bis(4-pyridyl)ethane; dpe=1,2-bis(4-pyridyl)ethene; 4,4′-bipy=4,4′-bipyridine; bpy=2,2′-bipyridine}. These complexes are all characterized by IR, elemental analysis, X-ray diffraction, luminescence, 31P NMR and 1H NMR spectroscopy. Complex 5 has an irregular (6,3) network structure connected through hydrogen bonds between the C–H groups of aromatic rings and anions; complexes 1 and 2 are of 2D topological architectures which are linked by hydrogen bonds; complex 4 is of a 1D infinite zigzag chain structure formed by the bridging ligand dpe; complexes 3 and 7 are of dinuclear structures and complex 6 is of mononuclear structure. The choice of solvent and the type and coordination modes of the bipyridine derivatives are of importance in defining the structural and topological features of the resulting networks. In addition, the complexes 1–7 exhibit interesting luminescence in the solid state at room temperature. At the same time, we also studied the terahertz spectrum which provided some new informations of these complexes.

Crystal structure of a new manganese(III) complex with tetradentate Schiff base N,N′-O-phenylenebis(4-methoxysalicylideneimine)

A new manganese(III) complex [Mn(L)(NCS)] (1) is synthesized from the Schiff base ligand N,N′-O-phenylenebis(4-methoxysalicylideneimine) (H2L: derived from the condensation of 4-methoxy salicylaldehyde with O-phenylene-diamine) with Mn(NO3)2∙4H2O and KSCN in a methanol/water solvent mixture. This complex is characterized by elemental analysis, FT-IR and single crystal X-ray diffraction. It crystallizes in a monoclinic system, with space group P21/c and four molecules in the unit cell (Z = 4). The crystal structure shows [Mn(L)(NCS)] units joined together by the Mn∙∙∙S secondary bonding interaction (SBI) to form infinite zigzag chain structures.

Polynuclear silver(I) complexes of diphosphine ligands and isoquinoline: Synthesis, structural characterization and spectroscopic properties

The reactions of diphosphine ligands and isoquinoline (i-C9H7N) with Ag salts in the mixed solvent of methanol (MeOH) and dichloromethane (CH2Cl2) generate the complexes [Ag2(dppm)2(NO2)2]·(i-C9H7N)2 (1), [Ag2(dppm)2(i-C9H7N)2(BF4)](BF4) (2), {[Ag(dppe)(i-C9H7N)2](CF3SO3)·(i-C9H7N)}n (3), {[Ag(dppb)(i-C9H7N)2](BF4)2·(i-C9H7N)0.5}n (4) and {[Ag(dppb)(i-C9H7N)(CF3SO3)]·(i-C9H7N)}n (5). These complexes were all characterized by IR, elemental analysis, X-ray diffraction, luminescence, 31P and 1H NMR spectroscopy. Complexes 1 and 2 have dinuclear structures, while complexes 3, 4 and 5 have 1D infinite zigzag chain structures. Complexes 1 and 2 are metal clusters in which there exist Ag⋯Ag metal bonds, whilst in compounds 3, 4 and 5, two silver atoms are bridged by the diphosphine ligands to form the 1D infinite zigzag chains. Complexes 3 and 5 are 2D topologically promising architectures and complex 4 is a 3D topologically promising architecture. In addition, complexes 1–5 exhibit interesting fluorescence in the solid state at room temperature. At the same time, we also studied the terahertz spectra of the complexes, which show more accurate characteristics of each group of complex.

Self-assembly of organotin(IV) 4-fluorobenzeneseleninato complexes: 1D polymeric chain, helical double-chain polymer and tetranuclear cage

Four new organotin complexes, [Me3SnO2SeC6H4-F-p]n (1), [Ph3SnO2SeC6H4-F-p] (2), [Me2Sn(O2SeC6H4-F-p)2]n (3), and [(PhSn)4(μ2-O)2(O2SeC6H4-F-p)8] (4) have been synthesized via reactions of 4-fluorobenzeneseleninato ligand and the corresponding R3SnCl or R2SnCl2 (R = Me, Ph) with sodium ethoxide in methanol. All the complexes have been characterized by X-ray crystallography, elemental analysis, FT-IR, and NMR (1H, 13C, 119Sn) spectroscopy. The structural analysis indicates that complex 1 adopts a 1D infinite zigzag chain structure, complex 2 displays a 1D infinite linear polymeric chain structure, complex 3 is 1D helical double-chain polymer containing eight-membered Sn2O4Se2 inorganic ring, and complex 4 shows a tetranuclear cage structure containing two Sn–O–Sn motifs connected by bridging [p-F-C6H4SeO2]- ligands.

Synthesis and structural characterization of dinuclear Cd2+, Hg2+ and Fe2+ complexes with neutral bi and tetradentate flexible pyrazole-based ligands

Four new complexes of [Hg2Cl4(bpp)]n (1), [Hg2Cl4(tdmpp)] (2), [Cd2I4(tdmpp)] (3) and [Fe2Cl4(tdmpp)] (4) were prepared by using the neutral N-donor ligands 1,3-bis(3,5-dimethyl-1-pyrazolyl)propane (bpp) and 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane (tdmpp) with different flexibility and appropriate metal salts of Cd(II), Hg(II) and Fe(II) ions. These compounds were characterized by the infrared spectroscopy, elemental analysis and X-ray crystallography. Flexible ligands and non-covalent CH⋯Cl hydrogen bonds play a major role in the crystal packing of compounds 1, 2 and 4. In the two-dimensional non-covalent structure of 1, there are two distinctly different coordination modes for the mercury atoms. One mercury atom has pseudo-trigonal bipyramidal geometry and the other adopts a distorted tetrahedral environment. In the dinuclear structures of 2 and 4 the neutral molecules are linked together by the CH⋯Cl hydrogen bonds, forming an infinite one-dimensional zigzag chain structure. Compounds 2–4 are isostructural with each other.

Synthesis of 2D polymeric dicyanamide bridged hexa-coordinated Cu(II) complex: Structural characterization, spectral studies and TDDFT calculation

A rare 2D polymeric dicyanamide bridged hexa-coordinated copper(II) complex [Cu(L1′)(μ1,5-dca)2]n (1) (L1′=2-carboxypyrazine) has been synthesized from the reaction of Cu(NO3)2⋅6H2O, 2-pyrazinecarbonitrile (L1) and sodium dicyanamide (Nadca) in methanolic medium. Single crystal X-ray analysis reveals that the complex has a 2D infinite zigzag chain structure in which copper(II) ions are bridged by single dicyanamide ligand in an end-to-end fashion. Such 2-carboxypyrazine can be obtained on the way of metal-assisted nitrile hydrolysis which well connected with Cu(NO3)2⋅6H2O and dicyanamide (dca) to give rare 2D Cu(II) polymeric complex due to the flexibility in the coordination ability of the copper(II) ions within the polymeric chain. The geometry of the asymmetric unit of the complex was optimized in singlet state by DFT method with multilayer ONIOM model at doublet spin state accordance with repeating asymmetric unit only. The electronic spectrum of the complex is explained using TDDFT calculation.

Construction of Two One-Dimensional Coordination Polymers by 5-Chlorosalicylic Acid Plus N-Donor Ligand: Synthesis, Structure and Catalytic Properties

Two novel coordination polymers, namely, [Co(HL5)(4,4′-bpy)1.5(H2O)2]n·n(HL5) (1) and [Zn(HL5)2(4,4′-bpy)]n (2) (H2L5 = 5-chlorosalicylic acid), have been hydrothermally synthesized through the reaction of 5-chlorosalicylic acid with divalent transition-metal salts in the presence of N-donor ancillary coligand (4,4′-bpy = 4,4′-bipyridine). Polymer 1 exhibits one-dimensional (1D) infinite ladderlike chain, which is extended into a 2D supramolecular network via O–H···O hydrogen-bonding interactions. In polymer 2, 4,4′-bpy acts as a bidentate ligand to bind Zn(II) ions to form a [Zn(4,4′-bpy)]n infinite zigzag chain structure, which is linked by hydrogen bonds into a 3D suparmolecular assembly. Also, IR spectra, powder X-ray diffraction, fluorescence Properties and thermal decomposition process of polymers were investigated. Moreover, both compounds exhibit catalytic properties on degradation of methyl orange in Fenton-like process.

One-dimensional infinite chain structures of [Al2(OH)4(H2O)4]X2 (X = I, Br, Cl): an aggregate of Al2 species and a precursor of Al(OH)3

By a combination of the Rietveld full-profile fitting technique based on powder X-ray diffraction data and the single-crystal structure solving and refining method, one-dimensional infinite zigzag chain structures were observed in the structures of [Al2(OH)4(H2O)4]X2 (X = I, Br, Cl). These crystallize in the same monoclinic system and the same C2/c space group with different unit cell parameters from spontaneously hydrolyzed solutions of AlX3. Each chain is composed of a significant number of AlO6 octahedra that fall into two groups with reverse orientations and connect to each other by edge-sharing. Furthermore, the counterions intersperse among the chains forming strong van der Waals interactions. It was also discovered that each chain was an aggregate formed from the further hydrolysis of the Al2 species (Al2(OH)2(H2O)8(4+), a dimer formed by two octahedral Al(H2O)6(3+) monomers sharing an edge) and a building unit for constructing the infinite hexameric ring sheet in nordstrandite and gibbsite. These are three new structures, rarely solved from powder XRD data, of polyaluminum compounds, and they provide the first direct evidence of the aggregation processes of Al2 species and their subsequent evolution into an infinite zigzag chain as well as further evolution into an infinite hexameric ring layer as found in nordstrandite and gibbsite. Furthermore, they also represent the first three examples in which each polyaluminum species possesses a one-dimensional infinite chain structure formed by AlO6 octahedra via edge-sharing only.

Syntheses, characterizations, crystal structures, and in vitro antitumor activities of chiral triorganotin(IV) complexes containing (S)-(+)-2-(4-isobutyl-phenyl)propionic and (R)-(+)-2-(4-hydroxyphenoxy)propionic acid ligands

Four new chiral triorganotin(IV) carboxylates, [(R3Sn)(O2C13H17)] n (R = Me 1, Ph 2), [(R3Sn)(O2C13H17)] (R = n-Bu 3), and [(R3Sn)(O4C9H9)] n (R = Me 4), have been synthesized by reaction of (S)-(+)-2-(4-isobutyl-phenyl)propionic acid and (R)-(+)-2-(4hydroxyphenoxy)propionic acid with triorganotin(IV) chloride in the presence of sodium ethoxide. The complexes have been characterized by elemental analyses, FT-IR, NMR (1H, 13C, and 119Sn) spectra, and X-ray crystallography diffraction analyses. Structural analyses show that 1 has a 1-D infinite chiral zigzag chain structure. Complexes 2 and 4 have a 1-D spring-like chiral helical chain with a channel, while 3 is a monomer. Antitumor activities of 1–4 have been studied.

Structural diversity of terpyridine-based metal complexes with varied dicarboxylate auxiliary ligands

Six new metal complexes, [Zn2L2(1,2-bdc)2] (1), [CuZnL2(1,2-bdc)2] (2), {[Cu2L(1,3-bdc)2]·2H2O}n (3), {[Cu2L2(1,4-bdc)](NO3)2·2H2O}n (4), [Cu2L2(1,4-bdc)(SCN)2]·2H2O (5) and {[ZnL(dc)]·H2O}n (6), have been synthesized by the reactions of 4′-4-(1,2,4-triazol-1-yl)-phenyl-2,2′:6′,2″-terpyridine (L) and different dicarboxylate auxiliary ligands with the corresponding metal salt. Complexes 1 and 2, with 1,2-benzenedicarboxylate (1,2-bdc2−), have dinuclear molecular structures. Complex 3, with 1,3-benzenedicarboxylate (1,3-bdc2−), is a (3,3,4)-connected three-dimensional (3D) framework with a Point (Schläfli) symbol of (4.6.8)(4.6.8)(6.84.10), while 4, with 1,4-benzenedicarboxylate (1,4-bdc2−), has an infinite chain structure, and further addition of SCN− anions to 4 results in the formation of the dinuclear complex 5. When 1,4-benzenediacrylic acid (H2dc) was employed as auxiliary ligand, complex 6 was obtained, having an infinite zigzag chain structure. All the complexes were characterized by elemental analyses, IR and X-ray crystallography. The results showed that the nature of the auxiliary ligand has a great impact on the structure of the complexes. Furthermore, the photoluminescence of the Zn(II) complexes and the reversible anion exchange property of 4 were investigated.

Five novel metal–organic framework constructed by lanthanide metals and 2,2′-bipyridine-6,6′-dicarboxylate: Hydrothermal synthesis, crystal structure, and thermal properties

Five lanthanide coordination compounds, [Ln 3(bpdc) 4(Hbpdc)(H 2O) 2]·12H 2O (Ln Ce(1), Nd(2) and Pr(3)) and [Ln 2(bpdc) 3(H 2O) 3]·3H 2O (Ln Er(4) and Tm(5)) were obtained from 2,2′-bipyridine-6,6′-dicarboxylate acid and corresponding lanthanide salts by hydrothermal synthesis. Single-crystal X-ray diffraction reveals that 1–3 are isomorphous and isostructural, composed of one-dimensional infinite double zigzag chain structure, and further extended to two-dimensional networks via hydrogen bonds and π–π interactions; while isomorphous and isostructural 4–5 are zero-dimensional discrete moieties and further joined into three-dimensional framework by rich intermolecular hydrogen bonds and π–π interactions. The pyridyl nitrogen atoms and the carboxylate oxygen atoms of the bpdc ligand are coordinated to lanthanide ions, resulting into versatile coordination modes. Thermogravimetric analyses of 1–5 display a considerable thermal stability.

Syntheses, structures and properties of a series of photochromic hybrids based on Keggin tungstophosphates

Three inorganic–organic hybrids based on Keggin tungstophosphates and lanthanides, [Pr(NMP) 6(PW 12O 40)] n ( 1), [Eu(NMP) 6(PW 12O 40)] n ( 2), and [Er 2(NMP) 12(PW 12O 40)][PW 12O 40] ( 3) (NMP= N-methyl-2-pyrrolidone), have been synthesized and characterized by elemental analysis, IR, UV–vis, and single-crystal X-ray diffraction. Compounds 1 and 2 exhibit 1D infinite zigzag chain structures, while compound 3 exhibits an ionic asymmetric structure due to lanthanide contraction. The three compounds are all photochromic. The magnetic susceptibility for 1 measured over the range 2–300 K shows that there is the dominant antiferromagnetic interaction in the compound. The results of luminescent properties show that compound 2 displays an interesting selectivity for Zn 2+ ions.

Metal–organic frameworks (MOFs) constructed from Zn II/Cd II-2,2′-bipyridines and polycarboxylic acids: Synthesis, characterization and microstructural studies

Metal–organic frameworks with the compositions [Zn(bpy)(bdc)(H 2O)] n 1, [Zn(bpy)(btec) 1/2(H 2O)] n 2, [Cd(bpy)(bdc)(H 2O)] n 3 and Cd(bpy)(btec) 1/2(H 2O)] n 4 (H 2bdc = 1,4-benzenedicarboxylic acid = terephthalic acid, H 4btec = 1,2,4,5-benzenetetracarboxylic acid and bpy = 2,2′-bipyridine) have been synthesized and characterized using spectroscopic and single-crystal X-ray diffraction techniques. In these complexes, Zn II/Cd II-2,2′-bipyridine units and carboxylate anions exists as nodes and spacers respectively. An infinite 1D zig-zag chain structure is observed for both complexes 1 and 3, whereas complexes 2 and 4 display a 3D supramolecular architecture. The complexes are found to be photoluminescent, porous and show significant thermal stability.

Structural, electronic, and magnetic properties of3dtransition metal monatomic chains: First-principles calculations

In this paper we investigated structural, electronic, and magnetic properties of $3d$ (light) transition metal atomic chains using first-principles pseudopotential plane-wave calculations. Infinite periodic linear, dimerized linear, and planar zigzag chain structures, as well as their short segments consisting of finite number of atoms have been considered. Like Cu, the periodic, linear chains of Mn, Co, and Ni correspond to a local shallow minimum. However, for most of the infinite periodic chains, neither linear nor dimerized linear structures are favored; to lower their energy the chains undergo a structural transformation to form planar zigzag and dimerized zigzag geometries. Dimerization in both infinite and finite chains is much stronger than the usual Peierls distortion and appears to depend on the number of $3d$ electrons. As a result of dimerization, a significant energy lowering occurs which, in turn, influences the stability and physical properties. Metallic linear chain of vanadium becomes half-metallic upon dimerization. Infinite linear chain of scandium also becomes half-metallic upon transformation to the zigzag structure. An interplay between the magnetic ground state and the atomic as well as the electronic structure of the chain has been revealed. The end effects influence the geometry, the energetics, and the magnetic ground state of the finite chains. Structure optimization performed using noncollinear approximation indicates significant differences from the collinear approximation. Variation of the cohesive energy of infinite- and finite-size chains with respect to the number of $3d$ electrons is found to mimic the well-known bulk behavior. The spin-orbit coupling of finite chains is found to be negligibly small.

A nickel 1-D zigzag chain coordination polymer of 2-pyrazinecarboxylic acid

[Ni(pyza)2H2O] n has been synthesized by hydrothermal reaction of 2-pyrazinecarboxylic acid (Hpyza) and Ni(CH3COO)2 · 4H2O in the presence of 1,10-phenanthroline and structurally characterized by elemental analysis, IR, UV and single crystal X-ray diffraction. The title complex displays an infinite zigzag chain structure in which each nickel(II) center is coordinated by three nitrogen and three oxygen atoms to generate a NiN3O3 octahedral geometry. The existence of hydrogen bond leads to formation of the interpenetrating stacked structure.