1D Single Chain Research Articles

Thermal Transport in Poly(p-phenylene): Anomalous Dimensionality Dependence and Role of π-π Stacking.

For heat conduction along polymer chains, a decrease in the axial thermal conductivity often occurs when the polymer structure changes from one-dimensional (1D) to three-dimensional (3D). For example, a single extended aliphatic chain (e.g., polyethylene or poly(dimethylsiloxane)) usually has a higher axial thermal conductivity than its double-chain or crystal counterparts because coupling between chains induces strong interchain anharmonic scatterings. Intuitively, for chains with an aromatic backbone, the even stronger π-π stacking, once formed between chains, should enhance thermal transport across chains and suppress the thermal conductivity along the chains. However, we show that this trend is the opposite in poly(p-phenylene) (PPP), a typical chain with an aromatic backbone. Using molecular dynamics simulations, we found that the axial thermal conductivity of PPP chains shows an anomalous dimensionality dependence where the thermal conductivity of double-chain and 3D crystal structures is higher than that of a 1D single chain. We analyzed the probability distribution of dihedral angles and found that π-π stacking between phenyl rings restricts the free rotation of phenyl rings and forms a long-range order along the chain, thus enhancing thermal transport along the chain direction. Though possessing a stronger bonding strength and stabilizing the multiple-chain structure, π-π stacking does not lead to a higher interchain thermal conductance between phenyl rings compared with that between aliphatic chains. Our simulation results on the effects of π-π stacking provide insights to engineer thermal transport in polymers at the molecular level.

One-Pot Self-Assembly of Dinuclear, Tetranuclear, and H-Bonding-Directed Polynuclear Cobalt(II), Cobalt(III), and Mixed-Valence Co(II)/Co(III) Complexes of Schiff Base Ligands with Incomplete Double Cubane Core.

The reaction of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and tris(hydroxymethyl)aminomethane (THMAM) was investigated in the presence of Cobalt(II) salts, (X = ClO4−, CH3CO2−, Cl−, NO3−), sodium azide (NaN3), and triethylamine (TEA). In one pot, the variation in Cobalt(II) salt results in the self-assembly of dinuclear, tetranuclear, and H-bonding-directed polynuclear coordination complexes of Cobalt(III), Cobalt(II), and mixed-valence CoIICoIII: [Co2III(H2L−1)2(AP−1)(N3)](ClO4)2 (1), [Co4(H2L−1)2(µ3-1,1,1-N3)2(µ-1,1-N3)2Cl2(CH3OH)2]·4CH3OH (2), [Co2IICo2III(HL−2)2(µ-CH3CO2)2(µ3-OH)2](NO3)2·2CH3CH2OH (3), and [Co2IICo2III (H2L12−)2(THMAM−1)2](NO3)4 (4). In 1, two cobalt(III) ions are connected via three single atom bridges; two from deprotonated ethanolic oxygen atoms in the side arms of the ligands and one from the1-amino-2-propanol moiety forming a dinuclear unit with a very short (2.5430(11) Å) Co-Co intermetallic separation with a coordination number of 7, a rare feature for cobalt(III). In 2, two cobalt(II) ions in a dinuclear unit are bridged through phenoxide O and μ3-1,1,1-N3 azido bridges, and the two dinuclear units are interconnected by two μ-1,1-N3 and two μ3-1,1,1-N3 azido bridges generating tetranuclear cationic [Co4(H2L−1)2(µ3-1,1,1-N3)2(µ-1,1-N3)2Cl2(CH3OH)2]2+ units with an incomplete double cubane core, which grow into polynuclear 1D-single chains along the a-axis through H-bonding. In 3, HL2− holds mixed-valent Co(II)/Co(III) ions in a dinuclear unit bridged via phenoxide O, μ-1,3-CH3CO2−, and μ3-OH− bridges, and the dinuclear units are interconnected through two deprotonated ethanolic O in the side arms of the ligands and two μ3-OH− bridges generating cationic tetranuclear [Co2IICo2III(HL−2)2(µ-CH3CO2)2(µ3-OH)2]2+ units with an incomplete double cubane core. In 4, H2L1−2 holds mixed-valent Co(II)/Co(III) ions in dinuclear units which dimerize through two ethanolic O (μ-RO−) in the side arms of the ligands and two ethanolic O (μ3-RO−) of THMAM bridges producing centrosymmetric cationic tetranuclear [Co2IICo2III (H2L1−2)2(THMAM−1)2]4+ units which grow into 2D-sheets along the bc-axis through a network of H-bonding. Bulk magnetization measurements on 2 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Co(II) ions.

Self-Assembly of Antiferromagnetically-Coupled Copper(II) Supramolecular Architectures with Diverse Structural Complexities.

The self-assembly of 2,6-diformyl-4-methylphenol (DFMP) and 1-amino-2-propanol (AP)/2-amino-1,3-propanediol (APD) in the presence of copper(II) ions results in the formation of six new supramolecular architectures containing two versatile double Schiff base ligands (H3L and H5L1) with one-, two-, or three-dimensional structures involving diverse nuclearities: tetranuclear [Cu4(HL2−)2(N3)4]·4CH3OH·56H2O (1) and [Cu4(L3−)2(OH)2(H2O)2] (2), dinuclear [Cu2(H3L12−)(N3)(H2O)(NO3)] (3), polynuclear {[Cu2(H3L12−)(H2O)(BF4)(N3)]·H2O}n (4), heptanuclear [Cu7(H3L12−)2(O)2(C6H5CO2)6]·6CH3OH·44H2O (5), and decanuclear [Cu10(H3L12−)4(O)2(OH)2(C6H5CO2)4] (C6H5CO2)2·20H2O (6). X-ray studies have revealed that the basic building block in 1, 3, and 4 is comprised of two copper centers bridged through one μ-phenolate oxygen atom from HL2− or H3L12−, and one μ-1,1-azido (N3−) ion and in 2, 5, and 6 by μ-phenoxide oxygen of L3− or H3L12− and μ-O2− or μ3-O2− ions. H-bonding involving coordinated/uncoordinated hydroxy groups of the ligands generates fascinating supramolecular architectures with 1D-single chains (1 and 6), 2D-sheets (3), and 3D-structures (4). In 5, benzoate ions display four different coordination modes, which, in our opinion, is unprecedented and constitutes a new discovery. In 1, 3, and 5, Cu(II) ions in [Cu2] units are antiferromagnetically coupled, with J ranging from −177 to −278 cm−1.

H-bonding directed formation of 1D-single chains, 2D-sheets, and 3D structures in magnetically coupled tetranuclear nickel(II) complexes with incomplete double cubane core

Reactions of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and 2-amino-1,3-propanediol (APD) in the presence of nickel(II) salts, NiX2 (X=CH3CO2−, NO3−, Cl−, ClO4−, BF4−)/sodium azide (NaN3), and triethylamine (TEA), in one pot self-assemble giving tetranuclear coordination complexes of nickel(II) with an incomplete double cubane structural core: [Ni4(H2L−1)2(μ-CH3CO2)2(μ3-X)2(μ-1,1-N3)2]·2CH3OH {X=1,1,1-N3 (1A) and OCH3 (1B)}, [Ni4(H2L−1)2(μ-1,1-N3)2(N3)2(μ3-OCH3)2 (H2O)2] (2), [Ni4(H2L−1)2(μ3-1,1,1-N3)2(μ-1,1-N3)2(CH3OH)2Cl2]·4CH3OH (3), [Ni4(H4L1−1)2(μ3-1,1,1-N3)2(μ-1,1-N3)2(CH3OH)2(OH)2]·2H2O (4), and [Ni4(HL2−2)2(APD−1)2][ClO4]2·2H2O·2CH3OH (5). In 1–3, H2L−1, in 4, H4L1−1, and in 5, HL22− represent a singly deprotonated chiral, potentially pentadentate trianionic double Schiff base ligand, H3L; a singly deprotonated potentially heptadentate pentaanionic double Schiff base ligand, H5L1; and a doubly deprotonated potentially tetradentate trianionic single Schiff base ligand, H3L2 respectively. In 1A, 3, and 4 two dinickel (Ni2) units are connected through two doubly bridging end-on (EO) μ-azido and two triply bridging EO μ3-azido bridges and in 2, though two EO μ-azido and two μ3-1,1,1-methoxy bridges generating tetranuclear units. In each dinuclear unit two nickel centers are bridged through one μ-phenolate oxygen from H2L−1, one μ-CH3CO2−, and one EO μ3-azido nitrogen (1) and through one μ-phenolate oxygen from H2L−1/H4L1−1 and one μ3-methoxy oxygen (2)/one μ3-azido nitrogen (3 and 4). In 5, two nickel(II) ions in the dinuclear unit are bridged though phenoxide oxygen and alkoxide oxygen bridges and two dinuclear units are interconnected via six symmetry related alkoxide bridges forming tetranickel units. In 1–4 neutral tetranuclear [Ni4] units and in 5, cationic tetranickel [Ni4]2+ units are interconnected by a symmetrical network of H-bonding between coordinated/uncoordinated hydroxido groups in the side arms of the double Schiff-base ligands, coordinated hydroxide ion/chloride ion, and uncoordinated methanol/water molecules producing H-bonding stabilized 2D-sheet structures (1, 2, 4), a 1D-single chains (3), and a 3D structure (5). Bulk magnetization measurements on 1–4 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Ni(II) ions with coupling constants (J1, J2, and J3) ranging from 13.19 to 22.10, (−9.05) to (1.74), and 14.79 to 25.59cm−1 respectively (in the Ĥ=-2J1(Ŝ1Ŝ3+Ŝ2Ŝ4)-2J2(Ŝ1Ŝ4+Ŝ2Ŝ3)-2J3(Ŝ1Ŝ2)+D(ŜZ12+ŜZ22+ŜZ32+ŜZ42) expression). [Display omitted]

Cadmium(II)-Triazole Framework as a Luminescent Probe for Ca(2+) and Cyano Complexes.

A bidentate ligand, 1-{4-[4-(1H-1,2,4-triazol-1-yl)phenoxy]phenyl}-1H-1,2,4-triazole (TPPT), has been designed and synthesized. By using TPPT as a building block for self-assembly with Cd(NO3 )2 ⋅4 H2 O and CdCl2 ⋅10.5 H2 O, novel 1D double-chain {[Cd(TPPT)(NO3 )2 ]⋅3 H2 O}n (1) and 2D (4,4) layer [Cd(TPPT)Cl2 (H2 O)]n (2) have been constructed. When 1 was employed as a precursor and exposed to DMF or N,N'-dimethylacetamide (DMAC), the crystals of 1 dissolved and reassembled into two types of brown block-shaped crystals of 1D double chains: {[Cd(TPPT)2 (NO3 )2 ]⋅DMF}n (1 a) and {[Cd(TPPT)2 (NO3 )2 ]⋅DMAC}n (1 b). The anion-exchange reactions of complex 2 have also been investigated. After gently stirring crystals of 2 in CHCl3 /C2 H5 OH/H2 O containing NaBr, NaI⋅2 H2 O, or NaOAc⋅3 H2 O, the crystals retained their crystalline appearances. A remarkable single crystal to single crystal transformation was observed and 1D double chains of {[Cd(TPPT)Br2 ]⋅C2 H5 OH}n (2 a) and {[Cd(TPPT)2 I2 ]⋅CHCl3 }n (2 b), and 1D single chains of [Cd(TPPT)(H2 O)2 (CH3 COO)2 ]n (2 c), can be obtained. Luminescent properties indicate that 1 shows excellent selectivity for Ca(2+) and cyano complexes. To the best of our knowledge, this is the first example of a luminescent probe for Ca(2+) based on triazole derivatives.

Cyanide-bridged bi- and trinuclear heterobimetallic Fe(III)–Mn(III) complexes: Synthesis, crystal structures and magnetic properties

By employing trans-dicyano or pentacyanometalate as building block and using a bicompartimental Schiffbase based manganese(III) compound as assemble segment, two new cyanide-bridged heterometallic Fe(III)–Mn(III) complexes {[Mn(L)(H2O)][Febpb(CN)2]}·2CH3OH (1) and {[Mn(L)(H2O)]2··[Fe(CN)5NO]} (2) (bpb2– = 1,2-bis(pyridine-2-carboxamido)benzenate, L = N,N'-ethylene-bis(3-ethoxysalicylideneiminate) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis reveals binuclear FeMn and trinuclear FeMn2 structure, respectively, in which the cyanide precursor acts as mono- or bidentate ligand to connect the Mn(III) Schiff-base unit(s). Furthermore, these two complexes are self-complementary through coordinated aqua ligands from one complex and the free O4 compartments from the neighboring complex, giving dimeric and 1D single chain supramolecular structure. Investigation of the magnetic susceptibility of 1 reveals weak antiferromagnetic coupling between the adjacent Mn(III) ions. Based on the binuclear FeMn model, best fit of the magnetic susceptibilities of 1 leads to the magnetic coupling constants J =–1.37 cm–1 and zJ′ =–0.72 cm–1 (1).

Synthesis of two metal-porphyrin frameworks assembled from porphyrin building motifs, 5, 10, 15, 20-tetrapyridylporphyrin and their base catalyzed property

Opening catalytically active sites in metal organic frameworks is an issue of fundamental importance for the development of effective and efficient catalysts. In this work, we first reported two metal metalloporphyrin–organic frameworks (MMPFs) with unoccupied pyridine groups as base catalysts. The reaction of Mn(II) and Co(II) with 5,10,15,20-tetrapyridylporphyrin produces two different metal metalloporphyrin–organic frameworks, {[(MnTPyP)]·H2O}n (MMPF-Mn) and [(CoTPyP)]n (MMPF-Co) (TPyP=5,10,15,20-tetrapyridylporphyrin) under hydrothermal conditions. These two MMPFs have been fully characterized by single-crystal X-ray diffraction, powder XRD, elemental analysis and thermogravimetry (TG). MMPF-Mn displays a 3D network with a nbo topology, large and open hexagonal channels, MMPF-Co reveals a 1D single zigzag chain architecture. Interestingly, both MMPFs have a high thermal stability and opening basic pyridine group, which have been tested for the base catalyzed Knoevenagel condensation reaction. The catalytic study has demonstrated that MMPF-Mn catalysts having exposed pyridine group within 1D channel displayed an excellent performance for Knoevenagel condensation reaction. When MMPF-Mn was recycled four times, its catalytic activity remained with an inconspicuous decrease. We attribute MMPF-Mn showing a better performance than MMPF-Co to its active sites being aligned in extra-large cavity with an interior diameter of 20Å.

Controlling solid state gain media by deposition of silver nanoparticles: from thermally- quenched to plasmon-enhanced Nd(3+) luminescence.

We show the possibility of controlling the optical properties of Nd(3+) laser ions by using different configurations of metallic nanoparticles (NPs) deposited on a solid state gain medium. In particular, we analyze the effect of two different silver NP arrangements on the optical properties of Nd(3+) ions in LiNbO(3): a two-dimensional (2D) high density and disordered Ag NP distribution and a one-dimensional (1D) long single chain of Ag NPs. We demonstrate that while the 2D disordered distribution produces a thermal quenching of the Nd(3+) luminescence, the 1D single chain leads to the enhancement of the fluorescence from the (4)F(3/2) metastable state. The experimental data are theoretically interpreted by taking into account the different character, radiative or non-radiative, of the localized surface plasmonic modes supported by the Ag nanoparticle distributions at the excitation wavelength. The results point out the capabilities of rare earth ions as optical tools to probe the local plasmonic fields and are relevant to determine the optimal configuration of metallic arrays to improve the performance of potential rare earth ion based sub-micrometer lasers.

The structure and luminescence properties of three complexes based on bifunctional imidazole-dicarboxylate connector

Abstract To study the diverse coordination modes of the H 2 btib, three new coordination architectures, namely, [Ag(Hbtib)CH 3 CN] n ( 1 ), [Ag(Hbtib)] n ( 2 ) and [Pb(btib)(CH 3 OH) 2 ] n ( 3 ) (where H 2 btib = 4-((2-butyl-5-(2-carboxy-3-(thiophen-2-yl)prop-1-enyl)-1 H -imidazol-1-yl)methyl)benzoic acid) have been synthesized and characterized by elemental analysis, IR spectrum and single-crystal X-ray diffraction. Complex 1 exhibits 1D single chain structure, while 2 shows 1D double metal chain motif, and 3 features a 2D layer topology. Also, 1 , 2 and 3 display strong emission band in the solid state at room temperature.

Synthesis, Crystal Structures and Magnetic Properties of Cyanide-bridged Trinuclear and Ion-pair Heterometallic Complexes

A cyanide-bridged, trinuclear, heterometallic Pd(II)–Mn(III) complex [{Mn(L)(H2O)}2{(μ-CN)2Pd(CN)2}] and an ion-pair complex [Co(Phen)2(H2O)2][Pd(CN)4]·MeOH have been synthesised (L = N,N-ethylene-bis(3-ethoxysalicylideneiminate; Phen = 1,10-phenanthroline). Single X-ray diffraction analysis reveals the neutral trinuclear complex is self-complementary through coordinated aqua ligands from one complex and the free O4 compartments from the neighbouring complex, thereby giving a 1D single chain supramolecular structure. The ion-pair complex forms a three-dimensional network via intermolecular O…H–N hydrogen bond interactions. Magnetic susceptibility studies show overall weak antiferromagnetic coupling between adjacent Mn(III) ions in the trimeric complex.

Hydrogen-Bond Directed 1D and 3D Cyanide-Bridged Heterometallic Complexes: Synthesis, Crystal Structures and Magnetic Properties

By employing K2[Pd(CN)4] as building block, [Mn(L)(H2O)2]ClO4 or Mn(Phen)2Cl2 (L = N,N-ethylene-bis(3-methoxysalicylideneiminate; Phen = 1,10-phenanthroline) as assembling segment, a trinuclear cyanide-bridged heterometallic Pd(II)-Mn(III) complex {[Mn(L)(H2O)]2[Pd(CN)4]}2·4H2O (1) and a ion-pair complex [Mn(Phen)2(H2O)2][Pd(CN)4] (2) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis reveals the cyanide-bridged trinuclear complex 1 is self-complementary through coordinated aqua ligands from one complex and the free O4 compartments from the neighboring complex, therefore giving 1D single chain supramolecular structure. For complex 2, it is constructed into interesting 3D network depending on the intermolecular O···H–N hydrogen bond interactions. Investigation over magnetic susceptibility of complex 1 reveals the overall weak antiferromagnetic coupling between the adjacent Mn(III) ions. With [Pd(CN)4]2− as cyanide building block and bicompartimental schiff-base manganese(III) compound or Mn(II)-phenanthroline compound as assembling segment, one heterobimetallic cyanide-bridged trinuclear clusters and one heterobimetallic ion-pair complex have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination, in which the trinuclear complex 1 is self-assembled into one-dimensional chain structure by the intermolecular O–H⋯O hydrogen bond interactions, while the ion-pair complex 2 is linked into interesting three-dimensional network supramolecular structure by the intermolecular O–H⋯N hydrogen bond interactions. The trinuclear structure (top) and 1D single chain structure (bottom) constructed by intermolecular hydrogen bond interactions for complex 1. The crystal structure of ion-pair complex 2 (top) and its three-dimensional supramolecular structure constructed by intermolecular O-H⋯N hydrogen bond interactions (a axis (top), b axis (middle), c axis (bottom)). The magnetic property of complex 1.

Synthesis, structures and magnetic properties of 1D to 3D coordinated polymers based on series of flexible sulfide ligands

Five complexes [Mn 2O(L 1) 4] n ( 1), [Co(L 2)(H 2O) 2] n ( 2), [Co(L 3) 2(H 2O) 2] n ( 3) and [Co(L 4) 2(4,4′-bpy)(H 2O)] n ( 4) were obtained by using flexible organic ligands HL 1, HL 2, HL 3, and HL 4 in hydrothermal systems with cobalt, copper and manganese salts respectively (HL 1 = 2-(4-pyridylmethylthio)benzoic acid, HL 2 = 4-(4-pyridylmethylthio)benzoic acid, HL 3 = 2-(3-pyridylmethylthio)benzoic acid, HL 4 = 4-(2-pyridylmethylthio)benzoic acid). The five complexes have been characterized by X-ray single crystal diffraction, FT-IR spectrum and elemental analysis. Complex 1 is assembled to a 3D porous framework with Mn 2O units as nodes. Complex 2 shows 2D layer networks comprised of six-coordinated Co 2+ centers and L 2 − anionic ions. Complexes 3 and 4 have different 1D double or single chain structures. Various non-covalent bonds such as hydrogen bonds, π⋯π interactions, H-bond grids and S⋯S weak interactions lead to interesting supramolecular frameworks. DC (direct current) temperature dependent magnetic susceptibilities suggest weak antiferromagnetic behaviors exist in 1, and single ion paramagnetic along with spin-orbit coupling behavior dominate in 3 and 4.

A series of silver coordination polymers constructed from flexible bis(benzimidazole) ligands and different carboxylates

In this article, eight new silver coordination polymers constructed from two structurally related ligands, 1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole) (bbmb) and 1,1′-(1,4-butanediyl)bis(2-ethylbenzimedazole) (bbeb), have been synthesized: [Ag(L1)(bbmb)]·C 2H 5OH·H 2O ( 1), [Ag(L2)(bbmb)]·C 2H 5OH ( 2), [Ag(L3)(bbmb)] ( 3), [Ag 2(L4)(bbmb) 2]·C 2H 5OH ( 4), [Ag(L2)(bbeb)]·C 2H 5OH ( 5), [Ag(L5)(bbeb)]·CH 3OH ( 6), [Ag 2(L6) 2(bbeb)]·H 2O ( 7), and [Ag 2(L7)(bbeb) 2]·4(H 2O) ( 8), where L1 = benzoate anion, L2 = p-methoxybenzoate anion, L3 = 2-amino-benzoate anion, L4 = oxalate anion, L5 = cinnamate ainon, L6 = 3-amino-benzoate anion, and L7 = fumaric anion. In 1– 3, 5 and 6, the bidentate N-donor ligands (bbmb and bbeb) in trans conformations bridge neighboring silver centers to form 1D single chain structures. The carboxylate anions are attached on both sides of the chains. Moreover, 1 and 3 are extended into 2D layers, while 2 and 6 are extended into 3D frameworks through π–π interactions. In 4, the bbmb ligands bridge adjacent Ag(I) centers to form –Ag–bbmb–Ag– chains, which are further connected by L4 anions to form a 2D layer. The resulting layers are extended into 3D frameworks through strong π–π interactions. In 7, the N-donor ligands (bbeb) in trans conformations bridge two silver centers to generate a [Ag 2(bbeb)] 2+ unit. The adjacent [Ag 2(bbeb)] 2+ units are further connected via the L6 anions to form a 1D ladder chain. Moreover, the structure of compound 7 is extended into a 3D framework through hydrogen bonding and π–π interactions. In 8, two Ag(I) cations are bridged by two bbeb ligands in cis conformations to form a [Ag 2(bbeb) 2] 2+ ring, which are further linked by L7 anions to generate a 1D string chain. Furthermore, the hydrogen bonding and π–π interactions link L7 anions to form a 2D supramolecular sheet. Additionally, the luminescent properties of these compounds were also studied.

Solvothermal Synthesis, Crystal Structure, and Properties of a New Organic‐Templated Holmium Sulfate with 1D Single Ladder Chains

AbstractA new organic amine templated 1D holmium sulfate (C2H8N)[Ho(SO4)2·H2O] (1) has been synthesized and solvothermally and structurally characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetric and X‐ray diffraction analyses as well as scanning electron microscopy (SEM). The structure of framework 1 is constructed from HoO8 polyhedra and SO4 tetrahedra. S(1) and S(2) connects Ho(1) and its crystallographic partners by using three S–O–Ho linkages to generate double chains, whereas the adjacent double chain are connected by μ3‐O (O5) atoms to form a novel single ladder chains.

A series of coordination polymers constructed from flexible bis(benzimidazole)ether ligands and different carboxylates

Six new coordination polymers constructed from two structurally related ligands, 2,2′-bis(2-methylbenzimidazole) ether (L1) and 2,2′-bis(2-ethylbenzimidazole)ether (L2), have been synthesized. They are [Cu(L1)(bz)2] (1), [Cu(L2)(bz)2] (2), [Zn2(L1)(m-bdc)2] (3), [Cd2(L2)(m-bdc)2(H2O)]2·H2O (4), [Zn(L1)(OH-bdc)-(H2O)] (5) and [Zn2(L2)(btca)] (6), where Hbz = benzoic acid, m-H2bdc = 1,3-benzenedicarboxylic acid, OH-H2bdc = 5-hydroxyisophthalic acid, and H4btca = 1,2,4,5-benzenetetracarboxylic acid. In 1 and 2, the bidentate N-donor ligands (L1 and L2) bridge neighboring metal centers to form 1D single chains. The bz anions are attached on both sides of the chains. In 3 and 4, the N-donor ligands (L1 and L2) in cis conformations bridge two metal centers to generate a [M2(L1)]4+ unit (M = Zn(II) and Cd(II)). The adjacent [M2(L1)]4+ units are further linked via the dicarboxylate anions to form 1D double chain structures. In 5, the Zn(II) cations are bridged by OH-m-bdc anions to form an infinite polymeric chain. The L1 ligands are attached on one side of the chain in a monodentate mode. In 6, two Zn(II) cations are bridged by two L2 ligands to form a [ZnL2]2 4+ ring, which is further linked by btca anions to generate a 2D layer. The luminescent properties of the ligands and 3–6 in the solid state at room temperature were also studied.

Rational Design and Assembly of a New Series of Cyanide-Bridged FeIII−MnIIOne-Dimensional Single Chain Complexes: Synthesis, Crystal Structures, and Magnetic Properties

Two mononuclear seven-coordinated macrocycle manganese(II) compounds and three dicyanide-containing precursors have been employed as building blocks to assemble cyanide-bridged heterobimetallic complexes, resulting in five new cyanide-bridged single chain complexes {[Mn(L(1))][Fe(bpb)(CN)(2)]}ClO(4) x 0.5 H(2)O (2), {[Mn(L(2))][Fe(bpb)(CN)(2)]}ClO(4) x 0.5 H(2)O (3), {[Mn(L(1))][Fe(bpClb)(CN)(2)]}ClO(4) x H(2)O (4), {[Mn(L(2))][Fe(bpClb)(CN)(2)]}ClO(4) x 0.5 H(2)O (5), and {[Mn(L(1))][Fe(bpdBrb)(CN)(2)]}ClO(4) x H(2)O (6). Single X-ray diffraction analysis reveals their one-dimensional (1D) single cyanide-bridged cationic polymeric chain structure consisting of alternating units of [Mn(L)](2+) (L = L(1) or L(2)) and [Fe(L')(CN)(2)](-) (L' = bpb(2-), bpClb(2-) or bpdBrb(2-)) with free ClO(4)(-) as balanced anion. Similar to the mononuclear macrocyclic manganese(II) precursor {[Mn(L(2))(H(2)O)Cl]ClO(4)}.CH(3)OH (1), the coordination geometry of manganese(II) ion in all the 1D complexes is a slightly distorted pentagonal-bipyrimidal with two cyanide nitrogen atoms at the trans positions and N(5) or N(3)O(2) coordinating mode at the equatorial plane from ligand L(1) or L(2). Investigation of the magnetic properties of these five 1D single chain cyanide-bridged Fe(III)-Mn(II) complexes reveals the antiferromagnetic magnetic coupling between neighboring Fe(III) and Mn(II) ions through the bridging cyanide group. A best-fit to the magnetic susceptibilities of these complexes based on the 1D alternating chain model leads to the magnetic coupling constants J(1) = -1.16(2) and J(2) = -0.10(3) cm(-1) for 2, J(1) = -3.10(1) and J(2) = -0.25(1) cm(-1) for 3, J(1) = -1.10(1) and J(2) = -0.139(8) cm(-1) for 4, J(1) = -1.99(6) and J(2) = -0.57(1) cm(-1) for 5, and J(1) = -1.23(1) and J(2) = -0.13(5) cm(-1) for 6, respectively. This work will provide valuable information for the rational design and synthesis of low-dimensional, in particular, single chain, cyanide-bridged magnetic complexes.

Self-assembly of mixed-valence Co(ii/iii) and Ni(ii) clusters: azide-bridged 1D single chain coordination polymers comprised of tetranuclear units, tetranuclear Co(ii/iii) complexes, ferromagnetically coupled azide-bridged tetranuclear, and hexanuclear Ni(ii) complexes: synthesis, structural, and magnetic properties

One-pot reactions between 2,6-diformyl-4-methylphenol (DFMP) and 2-aminoethanol (AE) in the presence of cobalt(II) salts [Co(ClO4)2, CoCl2, Co(CH3CO2)2, Co(NO3)2] and sodium azide result in the self-assembly of novel one-dimensional single chain mixed-valence cobalt coordination polymers {[Co2(II)Co2(III) (HL)2(OCH3)2(N3)3]ClO(4).5H2O.CH3OH}n (1), {[Co2(II)Co2(III) (HL)2(OCH3)2(N3)3]Cl.H2O}n (2) in which tetra-cobalt cationic units are bridged by symmetrical 1,3-azides, forming single chains; mixed valence neutral tetranuclear clusters [Co2(II)Co2(III) (HL)2(OCH3)2(N3)4]CH3OH.2H2O (3), [Co2(II)Co2(III)(HL)2(OCH3)2(N3)2(CH3CO2)2].2CH3OH.2H2O (4), and the cationic cluster [Co2(II) Co2(III) (HL)2(OCH3)2(CH3OH)2(N3)2](NO3)2 (5). In all these reactions, H3L, the potentially pentadentate (N2O3), trianionic double Schiff base ligand 2,6-bis[(2-hydroxy-ethylimino)-methyl]-4-methylphenol is formed. The reaction between DFMP and AE in the presence of nickel(ii) salts and sodium azide in methanol-water mixture results in the self-assembly of ferromagnetically coupled hexanuclear complexes [Ni6(H2L)2(HL-1)2(H2O)2(N3)6](ClO4)(2).2CH3OH (6), and [Ni6(H2L)2(HL-1)2(CH3OH)2(N3)6](BF4)2 (7), involving double (H3L) and single (H2L-1) Schiff base ligands, and a neutral tetranuclear complex [Ni4(H2L)2(OCH3)2(CH3CO2)2(N3)2] (8) with only double Schiff-base (H3L). In these complexes, the nature of the anion and the reaction conditions seem to play an important role in directing the formation of tetranuclear, hexanuclear or polymeric clusters. All complexes involve divacant double cubane-type cores containing three to four different types of bridging ligands (phenoxy, azido, methoxy/alkoxy, and acetate). Variable temperature magnetic properties of these spin coupled clusters have been investigated and magneto-structural correlations have been established.

Synthesis, spectral and crystallographic characterization of manganese(II) coordination polymers based on aliphatic dicarboxylate and flexible bis(imidazolyl) derivatives

Two structurally related flexible imidazolyl ligands, bis( N-imidazolyl)methane (L 1) and 1,4-bis( N-imidazolyl)butane (L 2) reacted with Mn(II) salts of aliphatic dicarboxylic acids resulted in the formation of a number of novel metal-organic coordination architectures. All complexes have been structurally characterized by X-ray diffraction analysis. The different coordination modes of dicarboxylate anions due to their chain length, rigidity and diimidazolyl functionality lead to a range of different coordination structures. The coordination polymers exhibit 1D single chain, 2D sheet and 3D network structures. The aliphatic dicarboxylates can adopt chelating μ 2, bridging μ 2, and chelating–bridging μ 3 coordination modes, or act as uncoordinated counter anions. The central metal ions are coordinated in N 2O 4 and N 4O 2 fashions depending on the ancillary ligands. The topology of [Mn(male)(L 1)(H 2O) 2] ( 1, male = maleate) gives rise to singly bridged 1D chains, whereas compound [Mn(mal)(L 1)(H 2O)] · H 2O ( 2, mal = malonate) exhibits 2D sheets in which the metal centers are bridged by both imidazolyl ligands and dicarboxylates. Compounds [Mn(L 1) 2(H 2O) 2](suc) · 6H 2O ( 3, suc = succinate) and [Mn(L 1) 2(H 2O) 2](fum) · 6H 2O ( 4, fum = fumarate) show doubly bridged 1D chains, and the dicarboxylate groups are not coordinated but form 2D corrugated sheets with water molecules intercalated between the cationic layers. Compound [Mn(suc)(L 2)(H 2O) 2] ( 5, suc = succinate) was built from very flexible succinate and 1,4-bis( N-imidazolyl)butane which yielded three-dimensional interpenetrate networks, both succinate anion and the imidazolyl ligand act as bidentate bridging.

Synthesis and characterization of Cu(II), Co(II) and Ni(II) coordination polymers containing bis(imidazolyl) ligands

Two structurally related flexible imidazolyl ligands, bis( N-imidazolyl)methane (L 1) and 1,4-bis( N-imidazolyl)butane (L 2), were reacted with Cu(II), Co(II) and Ni(II) salts of aliphatic/aromatic dicarboxylic acids resulting in the formation of a number of novel metal–organic coordination architectures, [CuB 2(ox) 2(L 1) 2(H 2O) 2] · 4H 2O ( 1) (ox = oxalate), [Cu(pdc)(L 2) 1.5] · 4H 2O ( 2, pdc = pyridine-2,6-dicarboxylate), [Co(L) 2(H 2O) 2](tp) · 4H 2O ( 3, tp = terephthalate), [Ni(L 1) 2(H 2O) 2](ip) · 5H 2O ( 4, ip = isophthalate), [Cu 2(L 1) 4(H 2O) 4](tp) 2 · 7H 2O ( 5), [Co(mal)(L 1)(H 2O)] · 0.5MeOH ( 6, mal = malonate), [Co(pdc)(L 1)(H 2O)] ( 7). All the complexes have been structurally characterized by X-ray diffraction analysis. The different coordination modes of the dicarboxylate anions, due to their chain length, rigidity and diimidazolyl functionality, lead to a wide range of different coordination structures. The coordination polymers exhibit 1D single chain, ladder, 2D sheet and 2D network structures. The aliphatic and aromatic dicarboxylates can adopt chelating μ 2 and chelating-bridging μ 3 coordination modes, or act as uncoordinated counter anions. The central metal ions are coordinated in N 2O 4, N 4O 2, N 2O 3 and N 3O 3 fashions, depending on the ancillary ligands. The topology of 1 gives rise to macrocycles which are connected through hydrogen bonds to form 1D chains, whereas compound 2 exhibits a 1D polymeric ladder in which the carboxylate acts as a pincer ligand. Compounds 3– 5 show doubly bridged 1D chains, and the dicarboxylate groups are not coordinated but form 2D corrugated sheets with water molecules intercalated between the cationic layers. Compound 6 has a 2D network sheet structure in which each metal ion links three neighboring Co atoms by the bis( N-imidazolyl)methane ligand. The cobalt compound 7, with a 2D polymeric double sheet structure, is built from pincer carboxylate (pdc) and 1,4-bis( N-imidazolyl)methane ligands.

Bi3+/M2+ Oxyphosphate: A Continuous Series of Polycationic Species from the 1D Single Chain to the 2D Planes. Part 2. Crystal Structure of Three Original Structural Types Showing a Combination of New Ribbon‐like Polycations.

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