Supramolecular structures of CdX2-containing coordination compounds constructed by C–H ··· X synthons

Three CdX₂-containing (X = Cl, Br) compounds [CdBr₂(Him)₂] _n (Him = imidazole) (1), [CdCl₂(2,2′-bipy)] _n (2,2′-bipy = 2,2′-bipyridine) (2), and [CdCl₂(phen)] (phen = phenanthroline) (3) have been synthesized through hydrothermal technique. Compound 1 adopts 1-D coordination chain, which is connected to form a 3-D supramolecular network by inter-chain N–H ··· Br and C–H ··· Br hydrogen bonds. Compound 2 also adopts 1-D coordination chain, which is connected to form 3-D supramolecular network by intra- and inter-chain C–H ··· Cl hydrogen bonds; 3 is discrete, linked to form 2-D supramolecular sheets by intra- and inter-molecular C–H ··· Cl hydrogen bonds. The different volume and coordination ability of organic ligands result in the different coordination structure and supramolecular synthons. All these compounds exhibit strong fluorescence emissions at room temperature.     

Syntheses,structures and luminescent properties of a series of ladder-shaped [Ln2Sr3] heterometal-organic frameworks

A series of Ln^III–Sr^II heterometallic coordination polymers formulated as [Ln₂Sr₃(pda)₆(H₂O)₁₈]·nH₂O (Ln = Pr-1, n = 14; Nd-2, n = 12; Sm-3, n = 11; Eu-4, n = 11; Gd-5, n = 16; Tb-6, n = 13; Dy-7, n = 13) were synthesized via assembly of Ln(NO₃)₃·6H₂O, SrCl₂·6H₂O, pyridine-2,6-dicarboxylic acid (H₂pda) and imidazole (im) in H₂O/C₂H₅OH solution. Single crystal X-ray diffraction revealed that they are isostructural. All of these complexes possess ladder-shaped 1-D chain structures. The luminescent properties of Sm-3, Eu-4, Gd-5, Tb-6 and Dy-7 have been investigated. The solid-state quantum yields and the lifetimes of Eu-4 and Tb-6 are also studied.     

Synthesis,structures, and fluorescence of two cadmium(II) coordination polymers with a semirigid bis-benzimidazole

Compounds [CdLCl₂] _n (1) and {[Cd(L)₂(ClO₄)]·ClO₄} _n (2), where L?=?1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, have been synthesized by hydrothermal method, and characterized by element analysis, IR spectra, Powder XRD, and X-ray crystallographic diffraction. Cd(II) in 1 and 2 are both trigonal bipyramidal. Different cadmium salts of chloride and perchlorate lead to different configurations of [Cd₂L₂]²⁺, trans-form in 1 but trans and cis-forms in 2. The 1-D beaded chains of 1 are further linked to generate a 3-D supramolecular architecture by strong π–π stacking interactions as well as intermolecular C–H?···?Cl hydrogen bonds. In 2, the 1-D beaded chains are further assembled by intermolecular C–H?···?O hydrogen bonds to form a 2-D layer. Solid-state fluorescent properties of 1 and 2 were investigated at room temperature.     

Synthesis and crystal structures of cobalt(III), copper(II), nickel(II) and zinc(II) complexes derived from 4-methoxy-N′-(pyridin-2-ylmethylene)benzohydrazide with urease inhibitory activity

Abstract

Urease catalyzes the decomposition of urea into ammonia, which has harmful effects on both human health and fertile soil. Aiming at exploring novel urease inhibitors, a series of hydrazone compounds and their Co^III, Cu^II, Ni^II, and Zn^II complexes were prepared from 4-methoxy-N'-(pyridin-2-ylmethylene)benzohydrazide (HL). They are [CoClL(NCS)] (1), [CoL₂]·Cl·CH₃OH·H₂O (2), [CuL(NCNCN)]_n·nCH₃OH (3), [NiL(HL)]·ClO₄·CH₃OH (4) and [ZnClL(OH₂)]·CH₃OH (5). The compounds were characterized by physico-chemical methods. Structures of the complexes were further confirmed by single crystal X-ray diffraction. The metal ions in 1, 3, and 5 display square pyramidal coordination and 2 and 4 display octahedral coordination. The inhibitory effects of the compounds on Jack bean urease were evaluated. The results showed that 3 has effective urease inhibitory activity, with IC₅₀ value of (7.3?±?1.0) μmol L^?1.     

Syntheses and structures of three coordination polymers based on 4-methylbenzenethiolates of Zn(II) and Cd(II) and bipyridine

Using 4-methylbenzenethiolates of Zn or Cd as precursors and 4,4′-bipyridine (4,4′-bpy) as bridges, we have synthesized three new Zn(II)/Cd(II) coordination polymers, {[Cd(4,4′-bpy)₂(NCS)₂] · 2(SC₆H₄CH₃-4)₂} _n (1), {[Zn(4,4′-bpy)(SC₆H₄CH₃-4)₂] · DMF} _n (2) and {[Zn(4,4′-bpy)(SC₆H₄CH₃-4)₂] · H₂O · 0.5CH₃OH} _n (3). Compound 1 is a 2-D sheet-like square polymer in which four 4,4′-bpy ligands and two isothiocyanate ligands complete the octahedral Cd(II) coordination sphere. Compounds 2 and 3 have similar coordination around Zn(II), but have different polymer structures. In 2, Zn(II) centers are linked via a bidentate 4,4′-bipyridine to form 1-D twisted arched chains, which is a new structural type for Zn(II). Compound 3 has 1-D zigzag chains. The 2-D sheets in 1 and 1-D chains in 2 and 3 are assembled via intermolecular C–H ··· π and C–H ··· S interactions into 3-D supramolecular networks. C–H ··· S interactions are a vital factor in constructing the sulfur-containing coordination polymers. Different coordination modes and packing schemes in 1–3 show that the guest molecule has a critical influence on formation of polymers.     

Syntheses,crystal structures,and photophysical properties of two 2-D coordination polymers with different geometries of lead(II)

Two complexes constructed from aromatic acid and N-heterocyclic ligands have been synthesized by hydrothermal reaction: [Pb(cipt)(NDC)]_n (1) [cipt?=?2-(3-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, NDC?=?naphthalene-1,4-dicarboxylic acid] and [Pb(ipm)(BDC)₂]_n (2) [BDC?=?terephthalic acid, ipm?=?5-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-2-methoxyphenol]. Single-crystal X-ray analysis shows that 1 exhibits an interesting arm-shaped chain structure. 1-D ladder chain structure is formed by N–H···O bonding interactions and further into a 2-D network by N–H···O hydrogen bonds and interchain π–π stacking interactions. Complex 2 shows a 2-D butterfly wings structure, which has been rarely reported. The structure in 2 has intermolecular N–H···O interactions, which help in construction of the 3-D framework. In 1, the coordination sphere of Pb(II) is hemi-directed, whereas the Pb(II) geometry in 2 is holo-directed. The solid-state fluorescence spectra of 1 and 2 are also investigated, as well as the ligands cipt and ipm.     

Synthesis and Crystal Structures of Alkali and Alkaline Earth Metal Complexes of 3,5-Dinitropyrazolyl-4-carboxylate

The synthesis and crystal structures of 3,5-dinitro-1H-pyrazolyl-4-carboxylic acid (H₂dnpzc) and its four complexes with Ca²⁺, Ba²⁺, Na⁺ and K⁺ are reported in this paper. Ca(dnpzc) · 5H₂O exhibits a 1D polymeric structure, whereas Ba(dnpzc) · 4H₂O possesses a 2D structure. The structure of Na₂(dnpzc) · 4H₂O consists of 2D layers of [Na(dnpzc)]^–_n and 1D chains of [Na(H₂O)₃]⁺_n. K₂(dnpzc) · H₂O has a true 3D structure. It was observed that the doubly deprotonated ligand (dnpzc^2–) can act as a versatile bridge to form polymeric structures by varying combinations of its 8 potential donor atoms (two carboxy O atoms, two pyrazolyl N atoms and four nitro O atoms). Particularly in the structure of K₂(dnpzc) · H₂O, all the 8 donor atoms of dnpzc^2– take part in the coordination and as many as 10 potassium atoms are connected by one ligand.     

Three double- or triple-stranded chains constructed from different cobalt(II) salts and a flexible bis-triazole ligand

Three coordination compounds, {[Co(btrp)₂(H₂O)₂]?·?NO₃?·?H₂O} _n (1), {[Co(btrp)₂(H₂O)₂]?·?H₂O?·?2H₂btc} _n (2), and {[Co(btrp)₃]?·?2ClO₄} _n (3) (btrp?=?1,3-bis(1,2,4-triazol-1-yl)propane; H₃btc?=?benzene-1,3,5-tricarboxylic acid), have been prepared via solvothermal method and characterized by single-crystal X-ray diffraction and elemental analyses. Compound 1 possesses a 1-D double-stranded chain composed of ribbons of 20-membered cycles. Binuclear water clusters link adjacent nitrate anions to form a 1-D supramolecular helix in the structure. Compound 2 has a 1-D double-stranded chain wherein free H₂btc ligands constitute 1-D negative chains through classical hydrogen-bonding interactions (O–H?···?O). Compound 3 exhibits a triple-stranded 1-D chain. For 1–3, 3-D supramolecular structures are consolidated by interchain weak hydrogen-bonding interactions as well as electrostatic interactions.     

二元无机物标准熵 So298的拓扑研究

为了预测二元无机物的标准熵,基于分子图的连接矩阵和离子参数gi、qi,提出了一种新的连接性指数mQ, mG及其逆指数mQ’, mG’。 qi、gi定义为：qi=(1.1+Zi1.1) /(1.7+ni), gi=(1.4+Zi) /(0.9+ri+ri-1),其中Zi 、ni和 ri分别代表离子i的电荷数、最外层主量子数和半径。从0Q, 0Q’, 1G,和1G’,利用多元线性回归分析方法和人工神经网络方法,可以构建优良的QSPR模型。对371个二元无机物,其多元线性模型及神经网络模型的相关系数、标准偏差和平均绝对偏差分别是：0.9905, 8.29 J.K-1.mol-1, 6.48 J. K-1.mol-1, 0.9960, 5.37 J.K-1.mol-1 和 3.90 J.K-1.mol-1。留一法交叉验证表明,其多元线性模型具有良好的稳定性。两个模型对187个未进入模型的二元无机物的标准熵的预测值和实验值之间的相关系数、标准偏差和平均绝对偏差分别是：0.9897, 8.64 J. K-1.mol-1, 6.84 J. K-1.mol-1, 0.9957, 5.63 J.K-1.mol-1, 和 4.18 J.K-1.mol-1。研究表明,本文方法在预测二元无机物标准熵时比文献方法更有效,两种模型均能较精确的预测二元无机物的标准熵,且神经网络模型的预测结果更精确。     

Self-assembly of ionic triorganotin(IV) complexes of tetrafluorophthalic acid with a tetranuclear macrocyclic or polymeric structure: syntheses,characterization and crystal structures

Four triorganotin(IV) complexes constructed from tetrafluorophthalic acid (H₂tfp) with a 1?:?1?:?1 molar ratio of H₂tfp: Et₃N: R₃SnCl gave two of type {[R₃Sn (tfp)].Et₃NH}₄ (R?=?Me 1, R?=?n-Bu 2), and two of type [R₃Sn (tfp).Et₃NH] _n (R?=?PhCH₂ 3, Ph 4). All the complexes are characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR analyses. Complexes 1 and 4 were also confirmed by X-ray crystallography. Complex 1 is tetranuclear with a 28-membered C₁₆O₈Sn₄ macrocyclic ring system with a cavity. The supramolecular structure of 1 has been found to consist of a three-dimensional network built up by intermolecular N–H?···?O, C–H?···?O hydrogen bonds and C–F?···?F weak interactions. Complex 4 is an infinite polymeric structure. The salient feature of the supramolecular structure of 4 is that of a two-dimensional plane, in which intermolecular N–H?···?O and C–H?···?π hydrogen bonds are important.     

N-donor co-ligand-driven zinc coordination polymers based upon a bithiophene dicarboxylate: syntheses,structures, and luminescent properties

Three zinc compounds assembled from a bithiophene dicarboxylic acid (H₂DMTDC) and different N-donor co-ligands, [Zn(DMTDC)(bpt)(H₂O)]_n (1), {[Zn(DMTDC)(5,5-dmbpy)]·0.5DMF·1.5H₂O}_n (2), and {[Zn(DMTDC)(1,3-bimb)]·2DMF·H₂O}_n (3) (H₂DMTDC?=?3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, bpt?=?4-amino-3,5-bis(4-pyridyl)1,2,4-triazole, 5,5′-dmbpy?=?5,5′-dimethyl-2,2′-bipyridyl, 1,3-bimb?=?1,3-bis(imidazol-1ylmethyl)benzene), were solvothermally synthesized and characterized. Compounds 1 and 2 are 1-D linear and zigzag chains with different supramolecular structures. In 1, adjacent chains form zipper-like structures through N–H?N interactions. In 2, however, chains in adjacent layers are stacked in an unusual unparallel level through C–H?O interactions. Compound 3 features a highly corrugated 2-D (4,4) layer and the layers are penetrated by each other to give 3-D polycatenations. Right- and left-handed helical Zn-bimb chains are arranged alternately within and between the layers, leading to mesomeric property of the whole network. Thermal stability and the decomposed products of all compounds were investigated. Luminescent properties of the ligands and compounds in the solid state at room temperature have also been explored. Moreover, the luminescence intensities of the compounds in different solvents are largely dependent on the solvent.     

Study of phase transitions in 4-n-alkoxybenzilidene-4′-n-alkylanilines by one and two dimensional 13C NMR

Abstract

The phase transition of a series of homologous liquid-crystalline compounds, nO.m (4-n-alkoxybenzilidene-4′-n-alkylanilines), from the nematic phase to the smectic A phase has been studied by ¹³C NMR. The order parameters, determined by a two dimensional technique called separated local field spectroscopy combined with off-magic angle spinning, of different molecular segments of these compounds are related linearly to the ¹³C chemical shifts. Changes in the order parameters of the phenyl rings as well as those of the chains during the S_A–N transition depend on the nature of the phase transition. These changes are quantitatively related to the McMillan ratio, which is defined as the ratio between the S_A–N transition temperature (T _SAN) and the nematic to isotropic transition temperature (T _NI), i.e. M = T _SAN/T _NI. The S_A–N transition is first order for M > M _TCP, and second order for M < M _TCP, where TCP is the tricritical point. The value of M _TCP was found to be 0·958 ± 0·004, in excellent agreement with that obtained from spin probe studies (0·959 ± 0·005) reported by Freed and co-workers [1].     

Three new coordination frameworks based on 2-ethyl-imidazole-4,5-dicarboxylate and 1,10-phenanthroline: syntheses,crystal structures,and luminescence

Three new coordination polymers based on 2-ethyl-imidazole-4,5-dicarboxylate with 1,10-phenanthroline as ligands, Pb(HEIDC)(phen)₂ (1), [Zn(EIDC)(phen)] _n (2), and {[Ba(H₂EIDC)₂(phen)]?·?(phen)₂?·?[Ba(H₂EIDC)(HEIDC)(phen)]} _n (3) (H₃EIDC?=?2-ethyl-1-Himidazole-4,5-dicarboxylate; phen?=?1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complex 1 displays a tetranuclear square constructed of four Pb(II) centers, four HEIDC, and eight phen, resulting in a 3-D network with a 1-D open channel along the c-axis via C–H?···?O hydrogen bonds, C–H?···?π, and π–π stacking interactions. Complex 2 is an infinite zigzag chain resulting in the final 3-D supramolecular framework via C–H?···?O and π–π stacking interactions. Complex 3 is composed of two individual Ba chains, exhibiting a 3-D framework via O–H?···?O, O–H?···?N hydrogen bonds, and π–π stacking interactions. The photoluminescence spectra of 1 and 2 in the solid state have been investigated, 1 exhibits green photoluminescence in the solid state at room temperature.     

Complicated weak interactions in a hybrid material containing tetra(isothiocyanate)cobalt(II) and 1,1′-ethylene-2,2′-dipyridinium: synthesis,crystal structure,and magnetic properties

A new inorganic–organic hybrid material, [EtdiPy][Co(NCS)₄] (1) ([EtdiPy]²⁺?=?1,1′-ethylene-2,2′-dipyridinium), was synthesized and characterized by elemental analysis, IR spectrum, UV-Vis spectrum, ESI-MS, and single-crystal X-ray diffraction. Compound 1 is monoclinic, space group P2₁/n, with a?=?21.691(5)?Å, b?=?8.639(2)?Å, c?=?21.748(5)?Å, β?=?90.124(3)°, V?=?4075.1(16)?ų, D _c?=?1.550?g cm^?3, Z?=?8, F(000)?=?1928, and R ₁?=?0.0435. The C–H···S hydrogen bond, short S···C, S···N interactions, p···π, and π···π interactions observed in the solid state of 1 give a 3-D structure. Magnetic measurements from 2 to 300?K have shown weak antiferromagnetic exchange with θ?=??0.892?K in 1.     

Synthesis and crystal structures of Cd(II), Ni(II), and Mn(II) complexes of 1H-benzotriazole-1-acetic acid

Three new complexes: [Cd(btaa)(bipy)(CH₃COO) · H₂O] _n (1), [Ni(btaa)₂(H₂O)₄ · 6H₂O] _n (2), and [Mn(btaa)₂(H₂O)₂] _n (3) (bipy = 2,2′-bipyridine, Hbtaa = 1H-benzotriazole-1-acetic acid) were prepared and characterized by IR, elemental analyses, thermogravimetric analyses, and single-crystal X-ray analyses. In 1, cadmium ions are linked by btaa ligands into 1-D linear chains; the chains are extended into layers through C–H ··· O hydrogen bonds and π–π stacking interactions. Complex 2 is a mononuclear structure, extended to a 3-D network through multiple intermolecular hydrogen bonds. In 3, manganese is bridged by carboxylate groups of btaa in the syn–skew bidentate mode in two directions to form a 2-D grid-like framework with a (4, 4) topology. The solid-state fluorescence spectrum of 1 shows that the excitation peak is at 355 nm while the maximum emission peak is at 424 nm.     

Metal–organic supramolecular architectures derived from a new zwitterionic dicarboxylate ligand

A series of new coordination compounds with 1-carboxymethylpyridinium-4-benzoate (L) and transition metal ions have been synthesized. They are formulated as [M(L)₂(H₂O)₄]?·?4H₂O M=Mn (1) and Co (2), {[M(L)₂]?·?xH₂O} _n M=Mn, x?=?1 (3); M=Co, x?=?2 (4), and M=Cu, x?=?3 (5). In 1 and 2, the zwitterionic dicarboxylate ligand is monodentate through only one carboxylate to generate mononuclear molecules. The molecules are assembled through O–H?···?O interactions to give 3-D pillared layer-like architectures, in which interesting 1-D tape-like hydrogen bonding motifs are connected into 2-D layers via carboxylate-mediated hydrogen bonds. In 3–5, the organic ligands serve as bridges with one carboxylate monodentate and the other chelating, and the metal ions are linked by double bridges to give 1-D polymeric chains, which are zigzag (3) or stair-like (4 and 5) due to the cis or trans coordination geometry around metal ions. The chains are further stabilized and associated into 3-D architectures through intra- and interchain hydrogen bonding and/or π–π stacking interactions.     

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.     

Preparations,IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)₂Pd(CN)₄] (1) and [Cd(hydet-en)₂Pd(CN)₄] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H?···?O, N–H?···?N and O–H?···?N, thereby forming a three-dimensional network.     

Four Zn(II)/Cd(II) coordination polymers derived from isomeric benzenedicarboxylates and 1,6-bis(triazol)hexane ligand: synthesis,crystal structure,and luminescent properties

Four coordination polymers, [Zn(o-bdc)(bth)_0.5(H₂O)] _n (1), [Cd(o-bdc)(bth)_0.5(H₂O)] _n (2), [Zn(m-bdc)(bth)] _n (3), and [Cd(p-bdc)(bth)?·?(H₂O)₂] _n (4) (where o-bdc?=?1,2-benzenedicarboxylate, m-bdc?=?1,3-benzenedicarboxylate, p-bdc?=?1,4-benzenedicarboxylate, and bth?=?1,6-bis(triazol)hexane), have been hydrothermally synthesized and structurally characterized. Both 1 and 2 are isostructural, featuring two binodal architectures: (6³)(6⁵·8) topology in terms of o-bdc and Zn^II/Cd^II as three- and four-connected nodes. Complex 3 shows a 2-D (4,4) network with the Zn?···?Zn?···?Zn angle of 57.84°, whereas 4 exhibits planar 2-D (4,4) network. These 2-D networks of 3 and 4 are extended by supramolecular interactions, such as CH?···?π/π–π stacking and hydrogen-bonding into 3-D architecture. A structural comparison of these complexes demonstrates that the dicarboxylate building blocks with different dispositions of the carboxyl site play a key role in governing the coordination motifs as well as 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stabilities of 1–4 have also been studied.     

Crystal structures and magnetic properties of two isomorphic nickel(II) and cobalt(II) coordination polymers-based nitrogen-heterocyclic tricarbolylate ligands

5-(3,4-Dicarboxylphenyl) picolinic acid (H₃dppa) was applied as a new building block for the synthesis of two isomorphic coordination polymers, namely [Ni_1.5dppa(H₂O)₃]_n·nH₂O (1), [Co_1.5dppa(H₂O)₃]_n·nH₂O (2). Two compounds were generated by a hydrothermal self-assembly method using the corresponding metal(II) acetates and H₃cppa ligand. Structure analysis reveals that compounds 1 and 2 are isomorphic both featuring a two-dimensional wave structure and are finally extended into the three-dimensional supramolecular architecture though hydrogen bonding interactions. Magnetic susceptibility measurements indicate that domain a weak ferromagnetic exchange coupling between the adjacent Ni(II) centers in 1, and a weak antiferromagnetic coupling between Co(II) ions in for 2.