Sisi Feng

Self-assembly and magnetic properties of Ni(II)/Co(II) coordination polymers based on 1,4-bis(imidazol-1-yl)benzene and varying biphenyltetracarboxylates

Solvothermal or hydrothermal methods of M(NO3)2·6H2O (M = Ni(II) or Co(II)) with an N donor (1,4-bis(imidazol-1-yl)benzene, 1,4-bib) and auxiliary deprotonated biphenyltetracarboxylates (2,2′,5,5′-biphenyltetracarboxylic acid, H4(o,m-bpta); 3,3′,5,5′-biphenyltetracarboxylic acid, H4(m,m-bpta); or 3,3′,4,4′-biphenyltetracarboxylic acid, H4(m,p-bpta)) give five novel coordination polymers in H2O–DMF or H2O, namely, [Ni2(1,4-bib)3(o,m-bpta)(H2O)2] (1), [Ni2(1,4-bib)3(HCO2)4(H2O)2]·5H2O (2), [Co2(1,4-bib)2(m,m-bpta)(H2O)4] (3), [Ni2(1,4-bib)2(m,p-bpta)(H2O)2] (4) and [Co2(1,4-bib)2(m,p-bpta)(H2O)2] (5). The structural properties of the complexes have been acquired by single-crystal XRD and further characterized by EA, IR spectroscopy, powder XRD and TG analysis. The framework of 1 is constructed of a 3D interpenetration structure with a (4·62)2(42·62·82) topology. Complex 2 exhibits a 3D supramolecular framework assembled by 1D mutual interpenetration chains. Complex 3 generates a 3D supramolecular architecture from (4,4)-connected 2D layers. Complexes 4 and 5 exhibit isomorphism, having 2D sheet structures with (4,4)-grid units. These results reveal that the 1,4-bib ligand cooperating with different biphenyltetracarboxylic acids can be used as versatile building blocks for the construction of metal–organic frameworks. Magnetic susceptibility measurements indicate the presence of weak ferromagnetic exchanges between adjacent Ni(II) ions with g = 2.235(5), 2.223(7) and J = 0.906(1), 2.220(1) cm−1 for 1 and 4, respectively.

Self-assembly of lanthanide(III) coordination polymers from a bifunctional 2-(pyridin-2-yl)-1H-imidazole-4,5-dicarboxylate ligand with the assistance of oxalate: syntheses, structures, luminescence, and magnetic properties

Based on a bifunctional 2-(pyridine-2-yl)-1H-4,5-imidazole-dicarboxylic acid ligand, a novel family of lanthanide coordination polymers with formulas [Ln(HPIDC)(C2O4)0.5(H2O)]n (Ln = La, 1; Ce, 2) and [Ln2(HPIDC)(C2O4)2(H2O)3]n·2nH2O (Ln = Pr, 3; Nd, 4; Sm, 5; Eu, 6; Gd, 7; Tb, 8; Dy, 9; Ho, 10; Er, 11), (H3PIDC = 2-(pyridine-2-yl)-1H-imidazole-4,5-dicarboxylic acid & H2C2O4 = oxalic acid) has been prepared under hydro-solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, and thermogravimetric analysis. Notably, the ligands adopt the same μ3-kN,O:kO′,O′′:kO′′′ conformation in all compounds, which brings about two types of isostructural lanthanide coordination polymers. Namely, 1 and 2 crystallize in the monoclinic space group P21/n and are composed of [Ln2(COO)2] dinuclear subunits with networks having the symbol (63·82·10)2(63)2(8). Meanwhile, 3–11 crystallize in the monoclinic space group P21/c and are constructed with tetranuclear [Ln4(COO)4] subunits with networks having the symbol (103)2(104·122)(10)2. The photoluminescence measurement indicates that Eu(III) and Tb(III) coordination polymers show very strong reddish-orange and green emission bands with CIE chromaticity coordinates (0.612, 0.325) and (0.284, 0.523) and quantum yields of 54.3% & 34.7%, respectively. The magnetic properties of 3 and 7–11 are investigated, and the results indicate a ferromagnetic interaction between Gd(III) magnetic centers in complex 7 and antiferromagnetic interactions in other complexes.

Two N,N-dimethylbiguanidium salts displaying double hydrogen bonds to the counter-ions.

The crystal structures of N,N-dimethylbiguanidium oxalate monohydrate, C 4 H 13 N 5 2+ .C 2 O 4 2- .H 2 O, (I), and N,N-dimethyl-biguanidium sulfate monohydrate, C 4 H 13 N 5 2+ .SO 4 2- .H 2 O, (II), show that both compounds contain the same N,N-dimethylbiguanidium dication. In (I), two independent oxalate ions lie about inversion centres. Strong double hydrogen bonds, with D...A distances of 2.658 (2) and 2.830 (3) A in (I), and 2.722 (3) and 2.815 (3) A in (II), are present between N atoms of the N,N-dimethylbiguanidium moieties and either the carboxylate group of the oxalate anion or the sulfate anion.

The first example of rhombic dodecahedral CuBr clusters in a novel mixed-valence Cu( i , ii )– benzimidazole complex

Hydrothermal reaction of CuBr2 and 1,2-di(1H-benzoimidazol-2-yl)ethane-1,2-diol leads to the formation of a new mixed-valence copper(I,II) complex [(C7H5N2)(CuICuIIBr2)], which exhibits a two-dimensional layer structure, containing the first example of a rhombic dodecahedral CuBr [4,3] polyhedral column. The synthesis, crystal structure, electronic property, thermal stability and electrochemical characterization of this complex are investigated.

Single-crystal metal–organic microtubes self-assembled from designed D3 symmetrical nanoclusters with a capped triple-helix pentanuclear M5O6 core

Single-crystal metal-organic microtubular architectures have been fabricated from designed D(3) symmetrical nano clusters with a capped triple-helix pentanuclear M(5)O(6) core under hydrothermal conditions.

Binuclear Mn2+ complexes of a biphenyltetracarboxylic acid with variable N-donor ligands: syntheses, structures, and magnetic properties

Four new manganese(II) metal–organic frameworks based on H4bpta (H4bpta = 3,3′,5,5′-biphenyltetracarboxylic acid) and N-donor ligands, namely [Mn2(4,4′-bipy)(bpta)]n (1), [Mn2(1,4-bib)2(bpta)]n·2n(H2O·DMF) (2), [Mn2(1,3-bimb)2(bpta)]n·2nH2O (3), and [Mn2(1,4-bimb)2(bpta)]n·2nH2O (4) (4,4′-bipy = 4,4′-bipyridine, 1,4-bib = 1,4-bis(imidazol-1-yl)benzene, 1,3-bimb = 1,3-bis((1H-imidazol-1-yl)methyl)benzene, and 1,4-bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene), have been obtained under solvothermal conditions. In these complexes, the fully deprotonated bpta4− ligands link binuclear SBUs to construct 2D layers with (4,4)-connected topologies. Complex 1 is a 3D network with 1D zigzag chains built up from 4-connected bpta4− ligands that contain carboxylate groups bridging Mn2+ ions in a rather rare syn–syn geometry. Complex 2 exhibits a 3D porous network with syn–anti bridging dimeric subunits. Complex 3 is a (3,4)-connected 2D novel network with double helix chains formed by cis-1,3-bimb linkers. The structure of complex 4 is similar to that of 2, but it consists of tiny pores due to trans-1,4-bimb linkers. Magnetic studies reveal that 1 is perfectly fitted by the modified Fisher model to yield an effective intrachain antiferromagnetic coupling (J = −2.21(1) cm−1). Complexes 2–4 show antiferromagnetic interactions (J = −1.57(2) cm−1 for 2, and J = −0.68(2) cm−1 for 3) in dimeric units of Mn2(μ-COO)22+ related to double syn–anti and syn–syn carboxylate bridges. An important repetitive feature of all these complexes with syn–anti or syn–syn carboxylate bridges is that the antiferromagnetic coupling is very small. In addition, the gas sorption exploration of 2 exhibits relatively high sorption of CO2 but very low sorption of N2, making it a promising material for CO2/N2 separation.

Bis(μ-1,10-phenanthrolin-2-olato-κ3N, N':O)dicopper(I)(Cu-Cu) monohydrate

The crystal structure of the title compound, [Cu(2)(C(12)H(7)N(2)O)(2)].H(2)O, shows that this dinuclear complex has shorter Cu-N, Cu-O and Cu-Cu distances within the coordination sphere than similar reported complexes. The complex molecule is located on a centre of symmetry and the water molecule is on a twofold axis of the space group C2/c. The discrete complex molecules are extended into a two-dimensional supramolecular array via pi-pi stacking interactions, intermolecular Cu.Cu interactions and C-H.O hydrogen bonds.

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hydrogen phosphate trihydrate.

In the title hydrated molecular salt, 2C3H7N6 +·HPO4 2−·3H2O, three of the O atoms of the hydrogen phosphate anion are disordered over two positions, with relative occupancies of 0.763 (1) and 0.237 (1). In the crystal, the components are linked by N—H⋯N, N—H⋯O and O—H⋯O hydrogen bonds

Aspartate aminotransferase is potently inhibited by copper complexes: Exploring copper complex-binding proteome

Recent researches indicated that a copper complex-binding proteome that potently interacted with copper complexes and then influenced cellular metabolism might exist in organism. In order to explore the copper complex-binding proteome, a copper chelating ion-immobilized affinity chromatography (Cu-IMAC) column and mass spectrometry were used to separate and identify putative Cu-binding proteins in primary rat hepatocytes. A total of 97 putative Cu-binding proteins were isolated and identified. Five higher abundance proteins, aspartate aminotransferase (AST), malate dehydrogenase (MDH), catalase (CAT), calreticulin (CRT) and albumin (Alb) were further purified using a SP-, and (or) Q-Sepharose Fast Flow column. The interaction between the purified proteins and selected 11 copper complexes and CuCl2 was investigated. The enzymes inhibition tests demonstrated that AST was potently inhibited by copper complexes while MDH and CAT were weakly inhibited. Schiff-based copper complexes 6 and 7 potently inhibited AST with the IC50 value of 3.6 and 7.2μM, respectively and exhibited better selectivity over MDH and CAT. Fluorescence titration results showed the two complexes tightly bound to AST with binding constant of 3.89×106 and 3.73×106M-1, respectively and a stoichiometry ratio of 1:1. Copper complex 6 was able to enter into HepG2 cells and further inhibit intracellular AST activity.

Hexakis(dimethyl­ammonium) di-μ6-oxido-tetra-μ3-oxido-tetra­deca-μ2-oxido-octa­oxidodeca­vanadate(V) monohydrate

In the title compound, (C2H8N)6[V10O28]·H2O, the [V10O28]6− polymetalate anion has crystallographic mirror symmetry with six V atoms and 12 O atoms lying on the mirror plane. Each of the VV atoms adopts a distorted octahedral geometry. Eight terminal O atoms are bonded to VV atoms with double bonds and the others act as bridging atoms. In the crystal structure, a network of N—H⋯O and O—H⋯O hydrogen bonds helps to establish the packing.