Unique Topology Analysis by ToposPro for a Metal-Organic Framework with Multiple Coordination Centers.

The reactions of 2-(4-pyridyl) thiazole-4-carboxylic acid (Hptca) and CuCl2·6H2O have led to a novel 3D mixed-valence, four-copper-center, metal-organic framework (MOF) [Cu8Cl2(ptca)10·17H2O] n (1). The topology analysis using ToposPro software package for 1 resulted in three chain-based topology types of sra (42, 63, 8), pcu (412, 63), and dia (66) via choosing corresponding connection atoms as central atoms. The study indicates that connection atoms associated directly with multiple coordination centers are applicable to act as central atoms. This unique topology analysis approach is conceptually different from the current analytical methods which use node atoms as central atoms. In addition, complex 1 exhibits significant selective adsorption of CO2 over N2. This study provides a great example of the topological analysis of MOFs with multiple coordination centers.

A microporous anionic metal-organic framework for a highly selective and sensitive electrochemical sensor of Cu(2+) ions.

We first reported an anionic metal-organic framework for electrode material for the electrochemical detection of Cu(2+). The modified electrode shows an excellent selectivity, high stability and sensitivity, wide linear range and lower detection limit. This strategy for generating new electrode materials will be useful for preparing new sensors and reporters for biological systems.

Two Isostructural Metal-Organic Frameworks Directed by the Different Center Metal Ions, Exhibiting the Ferrimagnetic Behavior and Slow Magnetic Relaxation.

Two 3D isostructural metal-organic frameworks with 1D ferrimagnetic chains, formulated as [M3(L)(µ3-OH)2(H2O)4] [H4L = (1,1':4',1″-terphenyl)-2',3,3″,5'-tetracarboxylic acid, where M = Mn for 1 and Co for 2], have been successfully synthesized by employing different center metal ions and a multicarboxylate ligand under identical reaction conditions in this work. The single-crystal X-ray diffraction data of 1 and 2 reveal that the complexes are two 3D isostructural frameworks based on 1D [M3(OH)2]n chains composed of triangular subunits as rod-shaped secondary building units, which are classified as binodal 4,6-connected fry nets with the point symbol (5(10)·6(3)·7(8))(5(4)·6(2)). The magnetic properties revealed that complexes 1 and 2 exhibit ferrimagnetic behavior. Also, the alternating-current susceptibility of 2 displays slow magnetic relaxation, showing interesting magnetic behavior of a single-chain magnet with an effective energy barrier of 32 K.

Two porous luminescent metal-organic frameworks: quantifiable evaluation of dynamic and static luminescent sensing mechanisms towards Fe(3.).

Two novel porous luminescent metal-organic frameworks (MOFs, 1 and 2) have been constructed using 3,4-di(3,5-dicarboxyphenyl)phthalic acid using a hydrothermal method. Both MOFs can work as highly sensitive sensors to Fe(3+) by luminescent quenching. Analyses of the structures indicate a higher quenching efficiency of 2 because of the existence of active -COOH groups. Based on this consideration, the quenching mechanisms are studied and the processes are controlled by multiple mechanisms in which dynamic and static mechanisms of MOFs are discussed. Besides, the corresponding dynamic and static quenching constants are calculated, achieving the quantification evaluation of the quenching process. As expected, experimental data show that compound 2 possesses an overall quenching efficiency 6.9 times that of compound 1. Additionally, time-dependent intensity measurements, the shifts of the excitation spectrum and the appearance of a new emission peak all give visual proofs of the distinct mechanisms between the two MOFs.

Synthesis and identification of artificial antigen of forsythin / 中国中药杂志

The establishment of high specificity and sensitivity method of small molecule monoclonal antibody-based immunoassay has a great importance in the study of small molecule compounds in Chinese medicine, wherein synthesis of small molecule artificial antigen is a critical step in the preparation of small molecule antibodies. Oxidation method using sodium iodide was used to synthesize immunogenic antigen (FRn-BSA) and coating antigen (FRn-OVA) of forsythin. UV spectroscopy and thin layer chromatography showed that forsythin was successfully conjugated with BSA and OVA. After immuned FRn-BSA, the mice could specifically produce anti-forsythin antibodies with titer up to 1:8 000, and the linear range was from 1 mg x L(-1) to 100 mg x L(-1). In this paper, the artificial antigen of forsythin was successfully synthesized, which can be applied for preparation of monoclonal antibodies and establishment of appropriate immune method.

Synthesis, structural diversity and fluorescent characterisation of a series of d10 metal-organic frameworks (MOFs): reaction conditions, secondary ligand and metal effects.

Along with our recent investigation on the flexible ligand of H(2)ADA (1,3-adamantanediacetic acid), a series of Zn(II) and Cd(II) metal-organic frameworks, namely, [Zn(3)(ADA)(3)(H(2)O)(2)](n)·5nH(2)O (1), [Zn(ADA)(4,4'-bipy)(0.5)](n) (2), [Zn(2)(ADA)(2)(bpa)](n) (3), [Zn(2)(ADA)(2)(bpa)](n) (4), [Zn(2)(ADA)(2)(bpp)](n) (5), [Cd(HADA)(2)((4,4'-bipy)](n) (6), [Cd(3)(ADA)(3)(bpa)(2)(CH(3)OH)(H(2)O)](n) (7), and [Cd(2)(ADA)(2)(bpp)(2)](n)·7nH(2)O (8) have been synthesized and structurally characterized (where 4,4'-bipy = 4,4'-dipyridine, bpa = 1,2-bis(4-pyridyl)ethane and bpp = 1,3-bis(4-pyridyl)propane). Due to various coordination modes and conformations of the flexible dicarboxylate ligand and the different pyridyl-containing coligands, these complexes exhibit structural and dimensional diversity. Complex 1 exhibits a three-dimensional (3D) framework containing one-dimensional (1D) Zn(II)-O-C-O-Zn(II) clusters. Complex 2 exhibits a 2D structure constructed by 1D double chains based on [Zn(2)ADA(2)] units and a 4,4'-bipy pillar. Complexes 3 and 4 possess isomorphic 2D layer structures, resulting from the different coordination modes of carboxylate group of ADA ligands. Complex 5 features a 2D 4(4) layer in which ADA ligands and Zn(II) atoms construct a 1D looped chain and the chains are further connected by bpp ligands. Complex 6 is composed of 1D zig-zag chains that are entangled through hydrogen-bonding interactions to generate a 2D network. Complex 7 is a rare (3,5)-connected network. Complex 8 possesses a 3D microporous framework with lots of water molecules encapsulated in the channels. The structural diversity of the complexes perhaps mainly results from using diverse secondary ligands and different metal centre ions, and means the assistant ligand and metal centre play important roles in the design and synthesis of target metal-organic frameworks. This finding revealed that ADA could be used as an effective bridging ligand to construct MOFs and change coordination modes and conformational geometries in these complexes. The thermogravimetric analyses, X-ray powder diffraction and solid-state luminescent properties of the complexes have also been investigated.

Syntheses and crystal structures of a series of coordination polymers constructed from C2-symmetric ligand 1,3-adamantanedicarboxylic acid.

This article systematically investigates the influence of the properties of inhomogeneous N-auxiliary ligands and pH value on the helical structures of complexes based on C(2)-symmetric ligand 1,3-adamantanedicarboxylic acid (H(2)ADC). Five kinds of neutral ligands (phen=1,10-phenanthroline, bipy=4,4'-bipyridine, bpa=1,2-bis(4-pyridyl)ethane, bpe=1,2-bis(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane) were selected, and a series of new Zn(II)/Co(II) dicarboxylates have been synthesized by slow diffusion, namely, [Zn(phen)(ADC)(H(2)O)](2).CH(3)OH (1), {[Zn(ADC)(bpe)].H(2)O}(n) (2), {[Zn(ADC)(bipy)].2H(2)O}(n) (3), {[Zn(ADC)(bpa)](2).5H(2)O}(n) (4), {[Zn(ADC)(bpp)](2).CH(3)OH}(n) (5), {[Zn(ADC)(bpp)]}(n) (6), {[Co(ADC)(bpp)(CH(3)OH)(H(2)O)].CH(3)OH2 H(2)O}(n) (7), and {[Co(ADC)(bpp)]}(n) (8). Single-crystal X-ray structural analysis shows that complex 1 forms a 0D dinuclear with closed-loop unit. The complex 2 is a 2D layer framework. Compounds 3 and 4 are isomorphous with a small discrepancy and present one-dimensional chainlike structures. It is interesting that the 2D organic-inorganic hybrid frameworks containing meso-helical chains have been observed. Compound 5 is a 2D interpenetrated network with (4,4) topology, in which homochiral left-handed helical chains are arranged in an ABAB sequence parallel to the plane defined by (a,c), and right-handed helical chains running along the a axis are also observed in the solid state, resulting in a meso-helical structure. Compounds 6, 7, and 8 crystallize in a chiral space group P212121. Highly dimensional 6 and 8 are essentially isostructural and present a threefold interpenetrated 3D diamondoid network containing three helical chains, whereas 7 exhibits a 2D grid layer with a left-handed helical chain. Furthermore, thermal stability, X-ray powder diffraction, and the luminescent properties of 1-6 are also discussed.

New types of di-, tetra-, hexa- and octanuclear Ag(I) complexes containing 1,3-adamantanedicarboxylic acid.

This article represents a systematical investigation on the structures of silver(I) dicarboxylate incorporating secondary ligands, revealing that the secondary interactions could play an important role in interlinking low-dimensional entities to high-dimensional supramolecular frameworks. A new 2D silver(I) crystalline dicarboxylate, {[Ag(6)(ADC)(3)(H(2)O)(1.5)](2).5.18H(2)O}(n) (1) (H(2)ADC = 1,3-adamantanedicarboxylic acid), has been obtained by slow diffusion of corresponding precursors. To investigate the influence of the properties of pyridylic neutral ligands on the complex structures based on compound 1, five kinds of neutral ligands (bipy = 4,4'-bipyridine; bpa = 1,2-bis(4-pyridyl)ethane; bpe = 1,2-bis(4-pyridyl)ethene; bpp = 1,3-bis(4-pyridyl)propane; bpdap = N,N'-bis(3-pyridyl)-2,6-diaminopyridine) were selected, and a series of new silver(I) dicarboxylate have been synthesized: {[Ag(bpa)(HADC)]}(n) (2), {[Ag(bpp)(HADC)].CH(3)OH}(n) (3), {[Ag(4)(bpe)(3)(ADC)(2)].2H(2)O}(n) (4), {[Ag(bipy)(HADC)].H(2)O}(n) (5), {[Ag(2)(bipy)(2)(ADC)].6H(2)O}(n) (6), and [Ag(8)(bpdap)(4)(ADC)(4)].2C(2)H(5)OH.6H(2)O (7). Single-crystal X-ray structural analysis shows that complexes 1 and 4 are formed by hexanuclear and tetranuclear Ag(I) clusters with weak Ag-Ag interactions. Complexes 2 and 3 are dinuclear structures, 5 and 6 exhibit an infinite 1D chain structure, whereas 7 is a discrete octanuclear Ag(I) unit. The structures of 1-7 span from dinuclear, tetranuclear, hexanuclear, to octanuclear Ag(I) complexes, which indicates that secondary ligands do play important roles in the formation of such coordination architectures. Thermal stability, X-ray powder diffraction and luminescent properties of the compounds are also discussed.

Interplay of coordinative and supramolecular interactions in formation of a series of metal-organic complexes bearing diverse dimensionalities.

A series of new metal-organic coordination complexes, {[Ni(IP)(H(2)O)(4)].(2H(2)O)(SO(4))} (1), [M(IP)(mu(2)-SO(4))(H(2)O)(2)] (M = Zn 2 , and M = Mn 3 ), {[M(2)(IP)(2)(mu(2)-SO(4))(2)(H(2)O)(4)].2H(2)O} (M = Zn 4 , and M = Co 5 ), {[Mn(2)(IP)(mu(2)-SO(4))(H(2)O)(2)].(6.5H(2)O)(sdba)} (6), {[Mn(IP)(2)(H(2)O)(2)][Mn(pydc)(2)(H(2)O)(2)].(4H(2)O)} (7), {[Mn(IP)(fum)(H(2)O)].H(2)O} (8), {[M(3)(IP)(3)(fum)(3)].(8H(2)O)} (M = Cd 9, and M = Zn 10 ), {[Cd(2)(IP)(2)(bptc)(H(2)O)(2)].(7.3H(2)O)} (11), {[Zn(2)(IP)(2)(bptc)(H(2)O)(2)].(3H(2)O)} (12), {Cd(1,4-BDC)(IP)(H(2)O)].(0.5H(2)O)} (13), {[Mn(1,4-BDC)(IP)(H(2)O)].H(2)O} (14), {[Zn(2)(1,4-BDC)(2)(IP)].2.5H(2)O} (15) (IP = 1H-imidazo[4,5-f][1,10]-phenanthroline, H(2)sdba = 4,4'-sulfonyldibenzoic acid, H(2)pydc = pyridine-2,6-dicarboxylic acid, H(2)fum = fumaric acid, H(4)bptc = 3,3',4,4'-benzophenonetetracarboxylic acid and 1,4-H(2)BDC = 1,4-benzendicarboxylic acid) were prepared via self-assembly of pharmaceutical agent IP with different metal sulfates in the absence/presence of the carboxylate under mild conditions. All these compounds were structurally determined by single-crystal X-ray diffraction. Compounds 2-6 crystallize with N-donor chelating ligands and sulfate anion linkers. Complexes 2-6 possess sulfate anions with mu(2)-bridging modes, the roles of sulfate anions result in 1D chains (2 and 3) and dinuclear units (4, 5and 6). For complex 7 , two different Mn units are chelated by two IP and pydc ligands, respectively. Compound 8 is a 1D chain connected by fum ligands. Polymers 9-12 exhibit 2D network structures composed of tetrametallic and hexametallic clusters. The Cd(ii)/Zn(ii) layers are interdigitated in pairs for complexes 11 and 12 by stacking forces, which exhibit unusual 2D-->3D interdigitated architectures. In 13 and 14, they show 1D undulating and linear chains due to the different coordinate modes of 1,4-BDC. IP firstly acts in a tridentate mode via the two N atoms of pyridyl rings and the third N atom of imidazole ring, and the two carboxylate groups of 1,4-BDC ligand taking three types of coordinative modes connect Zn atoms into a complicated 3D network in 15 . The structural differences among complexes 1-15 indicate the backbone of such dicarboxylate ligands, nature of metal resources and the ratio of metal to ligand play important roles in modulating the formation of the coordination polymers. Thermal stabilities of these crystalline materials, fluorescent properties of these complexes and TD-DFT calculation of spectra of IP were also investigated.