Peng-Fei Yao

Coordination assemblies of the CdII–BDC/bpt mixed-ligand system: positional isomeric effect, structural diversification and luminescent properties

To further systematically investigate the influence of the positional isomeric ligands on the structures and properties of transition metal complexes, we synthesized six Cd(II) complexes with three positional isomeric dipyridyl ligands (4,4′-bpt, 3,4′-bpt and 3,3′-bpt) and three positional isomeric phenyl dicarboxylate anions (p-BDC, m-BDC and o-BDC), namely, [Cd3(p-BDC)3(4,4′-bpt)2(H2O)5]·H2O (1), [Cd(p-HBDC)(p-BDC)0.5(3,4′-bpt)] (2), [Cd4(p-BDC)4(3,3′-bpt)4]·9H2O (3), [Cd(m-BDC)(3,3′-bpt)(H2O)]·2H2O (4), [Cd(o-BDC)(3,3′-bpt)(H2O)]·(3,3′-bpt)·4H2O (5), [Cd(o-BDC)(3,4′-bpt)(H2O)]·H2O (6). Structural analysis reveals that 1 is composed of a three dimensional (3D) 4-connected net giving an interesting 3-fold interpenetrating architecture. 2 and 3 possess a similar two dimensional (2D) layer structures. 4 presents an infinite one dimensional (1D) tubular-like chain. 5 displays a 2D honeycomb structure consisting of a 1D metal–organic helical chain. 6 exhibits a 2D wave-like layer structure with a (44)-sql network. Structural diversities indicate that the nature of isomeric benzene–dicarboxylates and bpt ligands plays crucial roles in modulating structures of these complexes. Intermolecular forces have important effects on the formation and strengthening of the supra-molecular architecture in these complexes. Moreover, the luminescent properties of them have been briefly investigated.

Synthesis and structural characterization of 2D Zn(II), Cd(II), and Co(II) coordination polymers containing 3-chloro-1,2-benzenedicarboxylate and positional isomers of triazole-bipyridine

Three compounds, [Zn2L2(4,4′-bpt)2] n (1), [Cd2L2(3,4′-bpt)(H2O)2] n (2) and {[CoL(3,3′-bpt)(H2O)]∙H2O} n (3) (L = 3-Cl-1,2-benzenedicarboxylate dianion, 4,4′-bpt = 1H-3,5-bs(4-pyridyl)-1,2,4-itriazole, 3,4′-bpt = 1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole and 3,3′-bpt = 1H-3,5-bis(3-pyridyl)-1,2,4-triazole), based on three positionally isomeric triazole-bipyridine ligands, were synthesized. Structural analyses of 1–3 reveal diverse 2-D network structures, which are based on different [ML] n (M = Zn, Cd, Co) chains. In the [ZnL] n chains of 1, the carboxylic groups of L connect the adjacent Zn(II) centers with a monodentate bridging coordination mode (μ2-η1  /  η1 ). In 2, [CdL] n is a double chain connected by the carboxylic groups of L with μ3-η1  /  η2/η2 and μ3-η1  /  η1  /  η2 bridges. The [CoL] n chains of 3 are formed by the carboxylic groups of L with the μ2-η1  /  η2 coordination mode. The powder X-ray diffraction and the thermal stability of 1–3, the luminescent properties of 1 and 2, and the magnetic behavior of 3 have been briefly investigated.

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.

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.

A family of Zn(II)/Cd(II) halide systems incorporating 5,5′-di(pyridin-2-yl)-3,3′-bi(1,2,4-triazole)

By using 5,5′-di(pyridin-2-yl)-3,3′-bi(1,2,4-triazole) (2,2′-H2dbpt) as a building block, six new coordination complexes: Zn3(2,2′-Hdbpt)2(H2O)Cl4 (1), {[Zn2(2,2′-dbpt)Cl3]·Et3NH}n (2), {[Cd3Cl3(2,2′-dbpt)3]·2H2O}n (3), {[Cd3I3(2,2′-dbpt)3]·H2O}n (4), {[Cd2Br2(2,2′-dbpt)]·H2O}n (5), and [Cd2I4(2,2′-H2dbpt)]n (6), based on the M(II)/X (M = Zn, Cd; X = Cl, Br, I) system were generated. 1 and 2 bear a Zn3 supermolecule and a 1D wave-like chain, respectively. 3 and 4 are isostructural, giving a new 3D architecture with a (412·63) topology based on the [Cd6] ring as a node bridged by the μ2-Cl− ion and the μ2-I− ion, respectively. 5 is a 2D framework with a (32·62·72) topology based on the [Cd4] subunit. 6 reveals a 1D modified trapezoid chain with a (42·6) topology based on the trans-bridging 2,2′-H2dbpt. Based on the interesting structural results, the solid-state luminescence properties of complexes 1–6 were investigated, which revealed that the emission maximum wavelengths can be tuned in a large range of 403–498 nm. These results indicate that 2,2′-H2dbpt is not only an excellent building block to construct coordination complexes with interesting structures but also a good precursor to construct potential photoactive materials.

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.

pH-dependent Co(II) assemblies from achiral 2-benzothiazolylthioacetic acid: crystal structures, symmetry breaking, and magnetic properties

Based on an achiral 2-benzothiazolylthioacetic acid (HL) ligand, three Co(II) coordination compounds, {[Co(L)2(H2O)3]·H2O}n (1), [Co(L)2(H2O)2]n (2), and [Co(L)2(H2O)4]·2H2O (3), were obtained under different pH environments. Compound 1 possessing an interesting chiral 1-D helical double chain was synthesized with pH of 5.0~6.5, and the chiral symmetry breaking has been probed by single-crystal X-ray diffraction and circular dichroism spectroscopy. Switching pH to 4.0~5.0 and 3.0~4.0 resulted in achiral 2 and 3, respectively. Compound 2 has a 1-D chain structure and 3 is mononuclear. Three Co(II) complexes, {[Co(L)2(H2O)3]·H2O}n (1), [Co(L)2(H2O)2]n (2), and [Co(L)2(H2O)4]·2H2O (3), were obtained under diferent pH (HL = achiral 2-benzothiazolylthioacetic acid). Compound 1 was synthesized at pH 5.0~6.5 and possesses a chiral 1-D helical double chain structure, which achieved chiral symmetry breaking. Compound 2 was obtained at pH 4.0~5.0 and has a 1-D chain structure. Compound 3 was genenrated at pH 3.0~4.0 and is a mononuclear structure.

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.

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

Abstract Using the N-heterocyclic building block 5,5′-di(pyridin-3-yl)-3,3′-bi(1,2,4-triazole) (3,3′-H2dbpt), four 3-D coordination polymers with diverse connectivity, [M(3,3′-dbpt)]n, M=Co (1), M=Ni (2), M=Zn (3), and [Cd2(3,3′-dbpt)Cl2]n (4), were constructed. By changing the central metal ions, 3,3′-H2dbpt had three different coordination modes. Consequently, 1–3, which are isostructural, have a 3-D 4-connected topology with (42.84) Schläfli symbol. 4 has a 3-D (4, 6)-topology, with (43.63)2(46.66.83) Schläfli symbol. Both 1 and 2 reveal weak antiferromagnetic behavior. In addition, 3 and 4 exhibit purple and blue emission bands, respectively. These results indicate that 3,3′-H2dbpt is an excellent multi-connection linker to construct MOFs with interesting structures and properties.