Hai-Ye Li

Co(II)/Ni(II) coordination polymers incorporated with a bent connector: crystal structures and magnetic properties

The hydrothermal reactions of a bent ligand, 1H-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt), with Co/Ni(II) ions as well as a series of polycarboxylate co-ligands yielded five new coordination polymers, namely, {[Co2(fum)2(bpt)2(H2O)]·3H2O}n (1), {[Co(mal)(bpt)0.5(H2O)]·1.5H2O}n (2), {[Co2(bptc)(bpt)2(EtOH)(H2O)2]·2H2O}n (3), [Ni2(btc)(bpt)2(H2O)2]·6H2O (4), [Ni2(Hbidc)2(bpt)2]·7H2O (5) (here, H2fum = fumaric acid, H2mal = malonic acid, H4bptc = 3,3′,4,4′-benzophenone-tetracarboxylate acid, H4btc = 1,2,4,5-benzenetetracarboxylate acid, H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid). These complexes exhibit different architectures and magnetic behaviors: 1 has a 3D (3,5)-connected (42·6)(42·65·83) topology, showing field-induced spin-flop transition; 2 and 3 both have a (3,4)-connected topology, exhibiting normal antiferromagnetism, with a 3D (63)(63·83) symbol for 2and a 2D (62·8)2(64·82) symbol for 3, respectively. In 4 and 5, the topological analysis results reveal that 4 can be simplified to a 3D 4-connected NbO net, while 5 is a 3D trinodal (3,4,6)-connected (63)(65·8)(612·8·102) net. Both 4 and 5 exhibit spin-canted antiferromagnetism.

Coordination assemblies of the MII-tm/bpt (M = Zn/Cd/Co/Ni) mixed-ligand system: positional isomeric effect, structural diversification and properties

To further investigate the influence of the positional isomeric ligands on structural topologies, six new coordination polymers with three positional isomeric dipyridyl ligands (4,4′-Hbpt, 3,4′-Hbpt and 3,3′-Hbpt) and trimellitic acid (H3tm), namely, {[Zn3(tm)2(4,4′-Hbpt)2(H2O)2]·10H2O}n (1), [Zn3(tm)2(3,3′-Hbpt)2]n (2), {[Cd2(tm)(3,4′-bpt)(H2O)2]·H2O}n (3), {[Cd4(tm)2(3,3′-bpt)2(H2O)2]·3H2O}n (4), {[Co3(tm)2(3,4′-Hbpt)2(H2O)6]·2H2O}n (5), {[Ni3(tm)2(3,3′-Hbpt)4(H2O)2]·7H2O}n (6), have been synthesized under hydrothermal conditions and characterized. Structural analysis reveals that: 1 and 5 both have 3D 4-connected networks, with the (4.64.8)(42.63.8)2(44.62)2 Schlafli symbol for 1 and (42.52.72)(52.62.7.8)2(4.52.6.72)2 symbol for 5. 2 and 3 both have 3D (4,5)-connected networks, with the (34.42.52)2(42.84)(3.43.52.6.72.8)2 symbol for 2 and (34.42.52)2(42.84)(3.43.52.6.72.8)2 symbol for 3. 4 has a 3D trinodal (3,4,5)-connected net with the (3.44.53.6.7) (43.62.7)(44.62)(42.6)2(45.64.8)2 symbol. And 6 has a 2D (3,4)-connected layer with (3.62)2(3.4.62.72)2(5.63.82) symbol. These results indicate that the versatile coordination modes of tm and the isomeric nature of bpt play crucial roles in modulating structural topologies of these complexes. Moreover, the luminescent properties of 1–4 and the magnetic behavior of 5–6, have been investigated.

Syntheses and crystal structures of three pillared complexes based on H2AIP and triazole-bipyridine ligands

Three pillared polymeric complexes, {[Ni2(AIP)2(4,4′-bpt)(H2O)2]·4H2O}n (1), {[Co(AIP)(3,3′-bpt)]·H2O}n (2), and {[Ni(AIP)(3,3′-bpt)]·H2O}n (3) (H2AIP = 5-aminoisophthalic, 4,4′-bpt = 1H-3,5–bis(4-pyridyl)-1,2,4-triazole and 3,3′-bpt = 1H-3,5-bis(3-pyridyl)-1,2,4-triazole), have been hydrothermally synthesized and characterized by X-ray diffraction analysis. Both 1 and 3 have 2-D (6,3) honeycomb layers, which are further interlinked by bent pillared triazole-bipyridine ligands to form a bilayer structure. The structures can be simplified to a (3,4)- and (3,5)-connected geometrical topology, respectively. Compound 2 has a Co-AIP layer structure in which the layers are pillared by 3,3′-bpt spacers to form the 3-D CsCl net.

Asymmetric catalytic sulfoxidation by a novel VIV8 cluster catalyst in the presence of serum albumin: a simple and green oxidation system

A novel VIV8 cluster formulated as [V8O12(OH)4(CH3O)4(DAC)4]·7CH3OH (1) (DAC = 1,2-diaminocyclohexane) has been constructed successfully. Enantioselective oxidation of a series of alkyl aryl sulfides catalyzed by 1 is tested in an aqueous medium in the presence of serum albumin. The catalytic procedure is found to be simple and environmentally friendly. The influences of the parameters such as concentration of catalyst and oxidant, pH, and reaction time on the thioanisole as models are investigated. Under optimum conditions, 1 exhibits high conversion (up to 99%), excellent chemoselectivity (≥90% in all cases) and moderate enantioselectivity (up to 75% ee). After binding with serum albumin, the catalytic activity of 1 is promoted. The bovine serum albumin (BSA) and pig serum albumin (PSA) molecules have a more positive effect on the catalytic activity.

In situ synthesis, characterization, bovine serum albumin (BSA) binding studies of FeII/CoII/NiII complexes derived from a new double bis-triazole macrocyclic ligand

Abstract The design and synthesis of macrocyclic ligands has become a hot research field of coordination chemistry for their novel structures and intriguing properties. Starting from bis (5-amion-1H-1,2,4-triazole) ligand (L1), three macrocyclic complexes with a novel double bis-triazole macrocyclic ligand (L2), [MCl2L2] (M = Fe, Co, Ni), were designed and synthesized by in situ reaction. In the process of reaction, metal ions played a key role for contributing to the formation of novel macrocyclic structures. The molecular structures of complexes were characterized by single-crystal X-ray diffraction, and the detailed description of synthesis is presented in this paper. The fluorescence quenching spectra and UV–vis spectra were used to study the interaction of complexes with bovine serum albumin (BSA). The results showed that the fluorescence quenching of BSA by these complexes was the presence of static quenching.

Four CuI(ett) coordination polymorphs and changes in XRD upon hydrothermal condition optimization

Four [CuI(ett)]n coordination polymorphs (1-α, 1-β, 1-γ and 1-δ), based on 5-(ethylthio)-1H-tetrazole (Hett), have been prepared successfully. By regulating the reaction time and reaction temperature, the rich coordination mode of the ett ligands can be regulated. Consequently, 1-α, 1-β and 1-γ show 2D wave-like layers, while 1-δ shows a 3D network. Powder X-ray diffraction (PXRD) analysis of the bulk sample of 1 prepared through a hydrothermal procedure revealed that 1-α and 1-δ can be isolated through temperature-dependent and time-dependent experiments, respectively. Starting from an as-prepared sample of 1-α in aqueous solution, the conversion from 1-α to 1-δ has been tracked over time by PXRD, with observations of the intermediate phases of 1-β and/or 1-γ in the hydrothermal re-crystallization process.

A series of multidimensional MOFs incorporating a new N-heterocyclic building block: 5,5′-di(pyridin-4-yl)-3,3′-bi(1,2,4-triazole)

By using a new N-heterocyclic building block, 5,5′-di(pyridin-4-yl)-3,3′-bi(1,2,4-triazole) (4,4′-H2dbpt), six novel coordination polymers with diversiform connectivity from one- to three-dimensional were successfully constructed. By regulating the different auxiliary ligands, central metal ions, and some other synthetic conditions, 4,4′-H2dbpt adopted various coordination modes. Consequently, 1 adopts a 2D (3,6)-topology, with the (43)3(46.66.83)2 Schlafli symbol. 2 shows a 3D 8-connected topology with a (36.418.53.6) Schlafli symbol. 3 and 4, which are isostructural, both have a 2D 4-connected topology, with a (44.62) Schlafli symbol. 5 has a complex 3D porous architecture with a 1D solvent-filled channel. 6 reveals a 1D helical chain extended along a 4-fold screw axis. These results indicate that 4,4′-H2dbpt is an excellent multi-connection linker from which we can construct MOFs with interesting structures and properties.

1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) as ligand in Cd(II) complexes: synthesis, crystal structures, and fluorescence

Hydrothermal reactions of 1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) with CdCl2 and CdI2 yielded three new coordination polymers, {[CdCl(2,3′-bpt)(H2O)]·2H2O}n (1), {[Cd2I3(2,3′-H0.5bpt)2]}n (2), and [CdI3(2,3′-Hbpt)](2,3′-H2bpt)·H2O (3). Structural analysis reveals that 1 has a 1-D double chain structure; in 2, 2,3′-bpt bridges adjacent Cd(II) ions to form a 1-D twofold helical chain, which further connects via μ2-I-, giving a 2-D grid structure in the ab plane; 3 is mononuclear. These complexes are further connected through weak hydrogen bonding interactions, and/or weak π···π stacking interactions, to generate 3-D supramolecular structures. The fluorescence properties of 1 and 2 have been investigated in the solid state at room temperature. The hydrothermal reactions of 1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) ligand with CdCl2 and CdI2, yielded three new coordination polymers, namely: {[CdCl(2,3′-bpt)(H2O)]·2H2O}n (1), {[Cd2I3(2,3′-H0.5bpt)2]}n (2) and [CdI3(2,3′-Hbpt)](2,3′-H2bpt)·H2O (3). Complex (1) exhibits a 1-D double chain structure; In (2), 2,3′-bpt bridges adjacent Cd(II) ions to form a 1-D twofold helical chain, which further connects each other via μ2-I− ions, giving rise to a 2-D grid structure in the ab plane; While complex (3) is a mononuclear structure. In addition, the fluorescence properties of complexes (1) and (2) have been briefly investigated in the solid state at room temperature.

Coordination Assemblies of CoII, NiII, ZnII, and CuII with 3,3′,4,4′-Biphenyltetracarboxylic Acid and Three Positional Isomeric Ligands

Eight different complexes with three positional isomeric dipyridyl ligands (3,3′-Hbpt, 3,4′-Hbpt, and 4,4′-Hbpt) (here, 3,3′-Hbpt = 1H-3,5-bis(3-pyridyl)-1,2,4-triazole, 3,4′-Hbpt = 1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole, and 4,4′-Hbpt = 1H-3,5-bis(4-pyridyl)-1,2,4-triazole), as well as 3,3′,4,4′-biphenyltetracarboxylic acid (H4bptc), namely, {[M(bptc)0.5(3,3′-Hbpt)(H2O)2]·H2O}n (M = Co (1), M = Ni (2)), {[Zn2(bptc)(3,3′-Hbpt)2]·3H2O}n (3), [Co(bptc)0.5(3,4′-Hbpt)(H2O)]n (4), [Ni(bptc)0.5(3,4′-Hbpt)2(H2O)2]n (5), {[Cu(bptc)0.5(3,4′-Hbpt)(H2O)]·H2O}n (6), and {[M(bptc)0.5(4,4′-Hbpt)2(H2O)]·4H2O}n (M = Co (7), and Ni (8)) were synthesised and characterised by single-crystal X-ray diffraction. The crystallographic analysis demonstrates that bptc influences the MII (M = Co, Ni, Cu, and Zn) ions to form 2D layers, which are further connected via the isomeric bpt connectors, leading to many types of coordination polymers, such as 2D layers(for 1–3, 5), 3D four-connected nets with a short Schlafli symbol of (64.82) (for 4, 6), and 3D four-connected nets with a short Schlafli symbol of (64.82)(5.63.72)0.5 (for 7–8). This work demonstrates that the isomeric effects of the bpt ligands influence the construction of these frameworks. The thermal stability of complexes 1–6 was investigated.

Synthesis, structures, and properties of a family of 3 d -based MOFs constructed from mixed ligands

By the use of co-ligands tri(2-carboxyethyl)-isocyanurate) (H3tci) and 1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole (3,4′-bpt), three coordination complexes, [Co3(tci)2(3,4′-bpt)2(H2O)4]·4H2O (1), [Cu3(tci)2(3,4′-bpt)2]·2H2O (2), and [Zn3(tci)2(3,4′-bpt)2(H2O)4]·4H2O (3), have been prepared by solvothermal methods and characterized by physicochemical and spectroscopic methods. Complexes 1 and 3 adopt a 3D (34) topology with the short Schläfli symbol of (6.82)4(62.82.102), both of them exhibiting threefold-interpenetrated networks. Complex 2 has a 2D 4-connected topology with the short Schläfli symbol of (44.62). Variable-temperature magnetic susceptibility measurements indicate that complexes 1 and 2 have antiferromagnetic interactions between the metal ions.