One-dimensional coordination polymers generated from an oxadiazole-containing N,N′-bipyridine-type ligand and inorganic salts

Three new one-dimensional coordination polymers have been prepared using Hg(II), Ag(I) and Zn(II) inorganic salts in combination with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L6). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. In the solid state, compounds 1 and 3 (1: monoclinic, P2₁/n, a=5.5373(3) Å, b=16.7839(9) Å, c=16.8120(9) Å, β=92.8610(10)°, V=1560.52(15) ų, Z=4; 3: monoclinic, P2₁/n, a=7.2958(4) Å, b=11.7214(6) Å, c=16.3979(9) Å, β=101.1150(10)°, V=1375.99(13) Å³, Z=4) feature novel one-dimensional helical chain motif. Compound 2, however, (2: monoclinic, P2₁/c, a=5.5506(4) Å, b=16.5895(12) Å, c=16.6871(11) Å, β=95.424(2)°, V=1529.70(19) ų, Z=4) exhibits one-dimensional zigzag chain motif, which result from the different conformations adopted by the L6 ligand and also the different metal coordination geometry. The luminescent properties of three new compounds were investigated in the solid state.     

1-D and 2-D coordination polymers of lead(II) thiocyanate with substituted 2,2′-bipyridine ligand

Two lead(II)-thiocyanato coordination polymers with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dm-2,2′-bpy) and 4,4′-dimethoxy-2,2′-bipyridine (4,4′-dmo-2,2′-bpy) as chelating ligands were synthesized and characterized by elemental analysis, IR and ¹H-NMR spectroscopy, thermal behavior, and X-ray crystallography. These complexes have formulas [Pb(5,5′-dm-2,2′-bpy)(NCS)₂] _n (1) and [Pb(4,4′-dmo-2,2′-bpy)(NCS)₂] _n (2). The coordination numbers of Pb^II in 1 and 2 are four, PbN₄, with “stereo-chemically active” electron pairs and hemidirected coordination spheres. Considering Pb···S as weak bonds, 1 and 2 are 1- and 2-D coordination polymers, respectively. The supramolecular features in these complexes are guided/controlled by weak directional intermolecular interactions.     

Syntheses and characterization of two 1D Cu(II) coordination polymers with 2,2′:6′,2″-terpyridine ligand

The solution reactions of CuCl₂ with 2,2′:6′,2″-terpyridine (Terpy) and dicarboxylic acid (glutaric acid or suberic acid) afforded two 1D coordination polymers [Cu(Terpy)(C₅H₆O₄)] _n (I) and [Cu(Terpy)(C₈H₁₂O₄)] · 3H₂O (II) and their structures were characterized by IR, TG-DTA, and single-crystal X-ray diffraction. Crystallographic data for I: C₂₀H₁₆CuN₃O₄, M _r = 425.90, monoclinic, space group C2/c, a = 10.335(2), b = 21.193(4), c = 8.580(2) Å, β = 111.99(3)°, V = 1742.5(6) ų, Z = 4, ρ _c = 1.623 g/cm³, F(000) = 872, R = 0.0304 and wR = 0.0915; and those for II: C₂₃H₂₉CuN₃O₇, M _r = 523.03, triclinic, space group P \(\bar 1\), a = 8.362(2), b = 10.605(2), c = 14.617(3) Å, α = 73.26(3)°, β = 86.23(3)°, γ = 69.45(3)°, V = 1161.3(4) ų, Z = 2, ρ _c = 1.496 g/cm³, F(000) = 546, R = 0.0636 and wR = 0.1106. X-ray diffracion studies reveal that both complexes I and II feature 1D chain. The 1D polymer chains are connected by π-π-stacking interactions to generate 2D supramolecular layers.     

Thermochemistry of Cu(II) and Ni(II) complexes with N,N-di-n-butyl-N′-thenoylthiourea and N,N-di-iso-butyl-N′-thenoylthiourea

Two substituted N-acylthioureas and the respective Ni(II) and Cu(II) complexes were synthesized, namely: N,N-di-n-butyl-N′-thenoylthiourea (Hnbtu); N,N-di-iso-butyl-N′-thenoylthiourea (Hibtu); bis[N,N-di-n-butyl-N′-thenoylthioureato]nickel(II), [Ni(nbtu)₂]; bis[N,N-di-n-butyl-N′-thenoylthioureato]copper(II), [Cu(nbtu)₂]; bis[N,N-di-iso-butyl-N′-thenoylthioureato]nickel(II), [Ni(ibtu)₂]; bis[N,N-di-iso-butyl-N′-thenoylthioureato]copper(II), [Cu(ibtu)₂]. The standard (p^° = 0.1 MPa) molar enthalpies of formation and sublimation of the two N-acylthioureas were measured, at T = 298.15 K, by rotating-bomb combustion calorimetry and Calvet microcalorimetry, respectively. The standard (p^° = 0.1 MPa) molar enthalpies of formation of the Ni(II) and Cu(II) complexes were determined, at T = 298.15 K, by high precision solution–reaction calorimetry. From the results obtained, the enthalpies of hypothetical metal–ligand and metal–metal exchange reactions, in the gaseous phase, were derived, thus allowing a discussion of the gaseous phase energetic difference between the complexation of Ni(II) and Cu(II) to 1,3-ligand systems with (S,O) ligator atoms.     

Copper(II), zinc(II), and cadmium(II) coordination polymers with 2-methylglutarato and 4,4′-dipyridyldisulfide

Three new coordination polymers of copper(II), zinc(II) and cadmium(II), Cu(H₂O)(Dpds)(2-MGA) (I), [Zn(Dpds)(2-MGA)] · 1.25H₂O (II) and [Cd(H₂O)(Dpds)(2-MGA)] · 0.25H₂O (III) (Dpds = 4,4′-dipyridyldisulfide, H₂MGA = (RS)-2-methyl glutaric acid), have been synthesized and characteried by X-ray single crystal structure determination. The Cu atoms in I are alternately bridged by Dpds ligands and 2-methylglutarato ligands to generate 1D chain. The resulted chains are assembled via S...S weak interactions into 2D layers, which are through twofold 2D parallel/2D parallel mode inclined interpenetration to induce 3D supramolecular architecture. In II, the ZnN₂O₂ tetrahedras are bridged by 2-MGA anion and Dpds ligands to form 2D (4,4) networks, which are assembled via hydrogen bonds to 3D supramolecular architecture. The centrosymmetric binuclear units Cd₂(2-MGA)₂ in III are bridged by Dpds ligands to form 1D repeated rhomboids chains, which are interlinked via S...S weak interactions into 2D layer, and the resulting 2D sheets are inclined parallel into 3D network.     

Four Cu(II)/Co(II) coordination polymers based on N,N′-di(3-pyridyl)sebacicdiamide: influence of different carboxylate ancillary ligands on structures and properties

Four Cu(II)/Co(II) coordination polymers, [Cu(L)(BDC)(H₂O)]·3H₂O (1), [Cu(L)(DNBA)₂] (2), [Co(L)₂(DNBA)₂] (3), and [Co(L)(NIPH)(H₂O)]·H₂O (4) (H₂BDC = 1,4-benzenedicarboxylic acid, HDNBA = 3,5-dinitrobenzoic acid, H₂NIPH = 5-nitroisophthalic acid, L = N,N′-di(3-pyridyl)sebacicdiamide), have been synthesized under hydrothermal conditions. The structures of 1–4 have been determined by single-crystal X-ray diffraction analyses and 1–4 were further characterized by infrared spectroscopy and thermogravimetric analyses. Complex 1 is a 2-D polymeric layer with a 4-connected sql topology. Complex 2 displays a 1-D zigzag chain. Complex 3 possesses a 1-D double-chain structure. Complex 4 exhibits a ribbon chain based on the 1-D [Co–L]_nmeso-helical chain. Adjacent layers for 1 and adjacent chains for 2–4 are further linked by hydrogen bonding or π–π stacking interactions to form 3-D supramolecular networks. The differences of carboxylates and metal ions show significant effect on the ultimate architectures of the four complexes. Thermal stabilities, fluorescent properties and photocatalytic activities of 1–4 were also studied.     

Synthesis,crystal structures and photoluminescence of three new Mn(II) coordination polymers assembled from 2,4′-diphenic acid

Three new metal coordination polymers, [Mn(Hdpa)₂(4,4′-bipy)₂] _n (1), [Mn(dpa)(1,10-phen)(H₂O)] _n (2), and [Mn(dpa)(2,2′-bipy)] _n (3) (H₂dpa = 2,4′-biphenyl-dicarboxylic acid, 4,4′-bipy = 4,4′-bipyridine, 1,10-phen = 1,10-phenanthroline, and 2,2′-bipy = 2,2′-bipyridine), have been synthesized and characterized by elemental analysis, IR, and X-ray diffraction. Single-crystal X-ray analyses reveal that 2,4′-diphenic acid is a bridging ligand, exhibiting three coordination modes to link metal ions: μ ₁-η ¹: η ¹/μ ₀-η ⁰: η ⁰; μ ₂-η ²: η ⁰/μ ₁-η ¹: η ⁰; and μ ₂-η ¹: η ¹/μ ₂-η ¹: η ¹. Intermolecular hydrogen bonds in 1 lead to a zigzag chain. In 2, the 2-D supramolecular arrays extended along b-axis through π–π interactions between 1,10-phen. The dinuclear paddle-wheel second building units (SBUs) constructed by four dpa^2? ligands in 3 are linked by dpa^2? into double-strand chains. The fluorescence of H₂dpa and 1–3 are also determined.     

Syntheses,structures and magnetic properties of isonicotinate-bridged heterometallic Ln(III)–Cu(II) coordination polymers

The heterometallic Ln(III)–Cu(II) coordination polymers [CuLn₂(IN)₈(H₂O)₄] _n (IN?=?isonicotinate, Ln?=?Gd (1), Dy (2), Er(3)) have been synthesized by hydrothermal reactions and characterized by elemental analysis, IR and single crystal X-ray diffraction. The compounds are isomorphous and crystallize in monoclinic space group P2₁/c, adopting a one-dimensional chain structure with alternately arranged [Ln₂(IN)₆(H₂O)₄] and [Cu(IN)₂] building blocks bridged by isonicotinates. Temperature-dependent magnetic susceptibility for complex 1 was studied, and a very weak ferromagnetic interaction between metal ions was observed.     

Synthesis,crystal structure and magnetism of a one-dimensional Cu(II) coordination polymer with monodeprotonated 2,2′-bypyridine-3,3′-diol as bridging ligand

A new one-dimensional copper(II) coordination polymer, [Cu(μ-HL)(H₂O)₂(NO₃)] _n (HL = monodeprotonated 2,2′-bypyridine-3,3′-diol), was synthesized and its crystal structure determined by X-ray crystallography. In the crystal Cu(II) is located a distorted octahedral coordination geometry and each HL coordinates two Cu(II) ions with its two N atoms and an O atom of deprotonated hydroxyl, giving a one-dimensional chain. The variable-temperature (2–300 K) magnetic measurements, analyzed using a one-dimensional Cu(II) magnetic interaction formula, indicate the existence of very weak ferromagnetic coupling with 2J = 0.014 cm^?1.     

Synthesis,crystal structures,magnetic and luminescent properties of nickel(II) and cadmium(II) coordination polymers bearing 5-(2′-carboxylphenyl) nicotate ligands

Two coordination polymers, namely [M(cpna)(phen)(H₂O)] _n (M = Ni, 1; Cd, 2, H₂cpna = 5-(2′-carboxylphenyl) nicotic acid, phen = 1,10-phenanthroline), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, magnetic and luminescence measurements. Single-crystal X-ray diffraction studies show that the two complexes are isostructural polymers. They have 1D step-like chain structures, which are further extended into 3D metal–organic supramolecular frameworks by π–π stacking interactions. Magnetic studies for complex 1 show antiferromagnetic coupling between the adjacent Ni(II) centers, with g = 2.10 and J = −4.30 cm⁻¹. Complex 2 displays strong green fluorescent emission at room temperature.     

Polycarboxylate-assisted assembly of cobalt(II) metal–organic coordination polymers from a “V”-shaped tri-pyridyl-bis-amide ligand

The aim of this study was to explore the influence of the position and angles of carboxyl groups of polycarboxylates on constructing coordination polymers. Three Co(II) metal–organic coordination polymers based on a tri-pyridyl-bis-amide ligand, namely [Co(L)(1,2-BDC)(H₂O)₂]·2H₂O (1), [Co(L)(1,4-BDC)(H₂O)₂]·2H₂O (2) and [Co(L)₂(BTEC)_0.5]·H₂O (3) (L = N,N′-bis(pyridine-3-yl)pyridine-2,6-dicarboxamide, 1,2-H₂BDC = 1,2-benzenedicarboxylic acid, 1,4-H₂BDC = 1,4-benzenedicarboxylic acid, H₄BTEC = 1,2,4,5-benzenetetracarboxylic acid), have been obtained by tuning the auxiliary polycarboxylate ligands. Structural analyses reveal that complexes 1–3 display diverse structures. Complex 1 displays a meso-helical chain linked by L ligands, which is further extended into a three-dimensional supramolecular framework through hydrogen-bonding interactions. The 1,2-BDC with a chelating coordination mode only acts as the hydrogen bond acceptor. In complex 2, the 1,4-BDC anions connect adjacent Co(II) atoms to form a linear chain, which is connected by hydrogen-bonding interactions to construct a 3D supramolecular network. Complex 3 exhibits a chain, which is composed of left-/right-handed Co-L helical chains and Co-BTEC linear chain. The 1D chains are ultimately extended into a two-dimensional supramolecular network by hydrogen-bonding interactions. Moreover, the thermal stability and the fluorescent properties of the title complexes and the electrochemical behaviors of a bulk-modified carbon paste electrode with complex 2 have been investigated at room temperature.     

N,N′-dipyridoxyl(ethylenediamine) schiff-base ligand and its square-pyramidal copper(II) complex: Synthesis, experimental and theoretical characterization

A new tetradentate N,N??-dipyridoxyl(1,2-ethylenediamine) [=H₂ES] Schiff-base ligand and its Cu(II) salen complex [Cu(ES)(H₂O)] are synthesized and characterized by IR, UV-Vis, ¹H NMR, mass spectrometry, and elemental analysis. Their optimized geometries and theoretical vibrational frequencies are computed by using the density functional theory method where the B3LYP functional was used. Also, the ¹H NMR chemical shifts of the H₂ES ligand are calculated at the same computational level. In the optimized structure of the free ligand, two pyridine rings are not in the same plane. In the structure of the complex, the Schiff-base ligand acts as a dianionic tetradentate ligand in the N, N, O^?, O^? manner, so that the coordinating atoms occupy equatorial positions. The H₂O ligand occupies the axial position of the squarepyramidal complex. The calculated results are consistent with the experimental ones, confirming the suitability of the optimized structures for the H₂ES ligand and its Cu(II) complex.     

Hydrothermal synthesis, thermal and luminescent investigations of lanthanide(III) coordination polymers based on the 4,4′-oxybis(benzoate) ligand

In this study, new series of lanthanide 4,4??-oxybis(benzoates) of the general formula Ln₂oba₃·nH₂O, where Ln = lanthanides from La(III) to Lu(III), oba?=?C₁₂H₈O(COO) ₂ ^2? and n?=?3?C6, has been prepared under hydrothermal conditions. The compounds were characterized by elemental analysis, infrared spectroscopy, X-ray diffraction patterns measurements and different methods of thermal analysis (TG, DSC, and TG-FTIR). In addition, photoluminescence properties of the selected complexes have been investigated. Crystalline compounds are isostructural in the whole series. Both carboxylate groups are deprotonated and engaged in the coordination of Ln(III) ions. Heating of the complexes leads to the dehydration and next decomposition processes. Although of the same structure, the removal of water molecules proceeds in different ways. In the nitrogen atmosphere, they decompose releasing water, carbon oxides and phenol molecules. The complexes of Eu(III), Tb(III) and Dy(III) exhibit photoluminescence in the visible range, whereas the compounds of Nd(III) and Yb(III) in the near-infrared region upon excitation by UV light.     

Synthesis,crystal structures,and magnetic properties of two manganese(II) coordination polymers bearing 1,1′-biphenyl-3,3′-dicarboxylate ligands

Two Mn(II) coordination polymers, namely [Mn(bpda)] _n (1) and [Mn(bpda)(bpy)_0.5] _n (2) (H₂bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid and bpy = 4,4′-bipyridine), have been synthesized from H₂bpdc, bpy, and MnSO₄·2H₂O under hydrothermal conditions. The complexes were characterized by physicochemical and spectroscopic methods, as well as by X-ray crystallography. Compound 1 possesses a 3D structure consisting of carboxylate-bridged edge-sharing Mn–O–Mn double chains. Compound 2 features a 3D open structure with a dinuclear Mn(II) secondary building unit. Magnetic susceptibility measurements of compounds 1 and 2 exhibit antiferromagnetic interactions between the nearest Mn(II), with J = –11.3 cm⁻¹ and g = 2.12 for 1, and J = –13.5 cm⁻¹ and g = 2.12 for 2.     

Synthesis,characterization and antimicrobial activity studies of N - N ′-tetracarboxydiethyloxamide ligand and its metal(II) complexes

N-N′-tetracarboxydiethyloxamide (hereafter abbreviated as H₆L) was prepared by using L-aspartic acid and diethyl oxalate (DEO). A series of binuclear complexes of divalent metal chlorides viz. Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with H₆L have been prepared. Spectral studies (IR, UV and NMR) magnetic susceptibility, elemental analysis and molar conductance measurements confirm the formation of binuclear complexes, [M₂H₂L]/[M₂H₂L?·?4H₂O]. Electronic absorption spectra and magnetic susceptibilities suggest square-planar stereochemistry for Cu(II) and tetrahedral for Zn(II) complexes. Mn(II), Co(II), and Ni(II) coordinate two molecules of water and consequently show octahedral geometry. The in vitro antimicrobial activity of the synthesized compounds is discussed against bacterial strains such as S. aureus, S. epididermis, K. pneumonia, S. typhi, P. aerugenosa, and B. subtilis A. brasilense. The metal complexes show higher activity against all the microorganisms than the ligand.     

Linear oxalato- and 4,4′-dipyridyldisulfide-bridged copper(II) coordination polymer involving in situ ligand synthesis

The reaction of 1,3-bis(pyridyl-4-ylthio)propan-2-one with Cu(ClO₄)₂?·?6H₂O gave a new complex {[Cu₂(4PDS)₂(ox)(H₂O)₄](ClO₄)₂} _n (4PDS?=?4,4′-dipyridyldisulfide, ox?=?oxalate), with 4PDS and ox being created by the Cu(II)-assisted oxidation of 1,3-bis(pyridyl-4-ylthio)propan-2-one. The complex determined by X-ray crystallography is a 1D polymer, in which metallacycles formed by two 4PDS and two Cu(II) ions are further bridged through ox anions. It crystallizes in the orthorhombic system, space group Fddd, with lattice parameters a?=?15.106(2), b?=?23.667(4), c?=?27.637(3)?Å and Z?=?8.     

Synthesis,characterization, and crystal structure determination of Cu(II) coordination compounds with 2,2′-dimethyl-4,4′-bithiazole

[{CuCl(dm4bt)}₂ μ-Cl)₂] (1) (dm4bt = 2,2′-dimethyl-4,4′-bithiazole) was prepared from the reaction of CuCl₂ · 2H₂O with 2,2′-dimethyl-4,4′-bithiazole in methanol; [Cu(dm4bt)₂NO₃](NO₃) (2) was prepared from the reaction of Cu(NO₃)₂ · 3H₂O with 2,2′-dimethyl-4,4′-bithiazole in methanol. Both complexes were characterized by IR, UV–Vis spectroscopy, and single-crystal structure. The structure of 1 consists of centrosymmetric dimeric [{CuCl(dm4bt)}(μ-Cl)], in which two chloro ligands bridge the coppers forming a four-membered ring; a terminal chloride and a bidentate chelating bithiazole complete five coordination at each Cu(II) in a highly distorted trigonal-bipyramidal geometry. The mononuclear structure 2 consists of a Cu(II), two 2,2′-dimethyl-4,4′-bithiazoles, one monodentate nitrate and one uncoordinated nitrate in a highly distorted square pyramid.     

Antimicrobial studies of N - N ′-dicarboxydiethyloxamide and its Co(II), Ni(II), Cu(II) and Zn(II) complexes

Neutral complexes of Cu(II), Ni(II), Co(II), and Zn(II) have been synthesized from the oxamide-based ligand derived from leucine and diethyloxalate. The structural features have been deduced from their microanalytical, IR, UV/Vis, mass, ¹H and ¹³C NMR spectral data. The Co(II) and Ni(II) chelates have octahedral geometries and the Cu(II) chelate is a square-pyramidal geometry. The non-electrolytic and monomeric nature of the complexes is shown by their magnetic susceptibility and low conductance data. The biological activities of the ligand and its metal chelates against gram-positive and negative bacteria and fungi are also reported. All the compounds are antimicrobially active and show higher activity than the free ligand.     

On construction of lead coordination polymers derived from N′-(2-hydroxybenzylidene)nicotinohydrazide via covalent and non-covalent interactions

Lead(II) and lead(IV) coordination polymers with N′-(2-hydroxybenzylidene)nicotinohydrazide have been synthesized from lead(II) salts, and subsequently characterized by solid-state UV?Vis?IR spectroscopy, thermal analysis, and powder and single-crystal X-ray diffraction techniques. The compounds crystallize in the same space group but differ in the oxidation state of lead, composition, conformation of the organic ligand, its charge, and tautomeric form. The coordination network is propagated by the hydrazone anion in the lead(II) metal-organic framework catena-[(μ₂-N-((2-oxidophenyl)methylidene)pyridine-3-carbohydrazonoato-N:N′,O,O′)-lead(II) (1) and by nitrate in a one-dimensional lead(IV) coordination polymer catena-(μ₂-nitrato-O,O)-(nitrato-O,O′)-(salicylaldehydeisonicotinoylhydrazonato-N,N′,O)-lead(IV) nitrate (2). The formation of metal-organic framework of 1 is affected by Pb···π interactions.