Fu-Ping Huang

A case study of the ZnII-BDC/bpt mixed-ligand system: positional isomeric effect, structural diversification and luminescent properties

To systematically investigate the influence of the positional isomeric ligands on the structures and properties of transition metal complexes, we synthesized eight Zn(II) complexes with three positional isomeric carboxylate ligands (p-BDC, m-BDC and o-BDC) and three positional isomeric dipyridyl bridging ligands (4,4′-bpt, 3,4′-bpt and 3,3′-bpt). {[Zn2(p-BDC)2(4,4′-bpt)2]·H2O·(C2H5OH)}n (1), {[Zn(p-BDC)(3,4′-bpt)2(H2O)2]·2H2O}n (2), {[Zn(p-BDC)(3,3′-bpt)2(H2O)2]·3H2O}n (3), {[Zn2(m-BDC)2(4,4′-bpt)(H2O)3]·H2O}n (4), [Zn(m-BDC)(3,4′-bpt)]n (5), {[Zn(m-BDC)(3,3′-bpt)]·H2O}n (6), [Zn(o-BDC)(4,4′-bpt)]n (7) and [Zn2(o-BDC)2(3,4′-bpt)]n (8) (p-BDC = 1,4-benzenedicarboxylate anion, m-BDC =1,3-benzenedicarboxylate anion, o-BDC = 1,2-benzenedicarboxylate anion, 4,4′-bpt = 1H-3,5-bis(4-pyridyl)-1,2,4-triazole, 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). Structural analysis reveals that the benzenedicarboxylate isomers display versatile coordination modes to manage the Zn(II) ions to form 1D chains (for 2–5, 7 and 8) or 2D layers (for 1 and 6), which are further extended via the isomeric bpt connectors in different directions to give rise to a variety of coordination polymers, such as 1D decorated chain, 1D ladder-like chain, 2D sql layer, 2D bilayer with 82·10 topology, 2D wave-like layer, 3D 2-fold interpenetrating porous pcu net and 3D CsCl net. These results indicate that the nature of isomeric benzenedicarboxylates and bpt ligands has an important effect on the structural topologies of such Zn(II) complexes. Moreover, the luminescent properties of the complexes have been briefly investigated.

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.

Four new copper(II) complexes with 1,3-tpbd ligand: Synthesis, crystal structures, magnetism, oxidative and hydrolytic cleavage of pBR322 DNA

Four copper(II) complexes [Cu(2)(1,3-tpbd)Cl(4)].EtOH (1), {[Cu(2)(1,3-tpbd)(mu-Cl)(2)](ClO(4))(2)(H(2)O)(4.5) (NaClO(4))}(infinity) (2), [Cu(2)(1,3-tpbd)(1,10-phen)(2)(H(2)O)(2)](ClO(4))(4) (3) and [Cu(2)(1,3-tpbd)(2,2-bpy)(2)(H(2)O)(2)](ClO(4))(4) (4) (1,3-tpbd=N,N,N,N-tetrakis(2-pyridylmethyl)benzene-1,3-diamine) have been synthesized and characterized by X-ray single crystal structure analysis. Variable-temperature magnetic susceptibility studies (2-300K) indicate the existence of antiferromagnetic coupling between the copper(II) ions in complexes 2 and 3. The interactions of the four complexes with calf thymus DNA (CT-DNA) have been investigated by UV absorption, fluorescent spectroscopy, circular dichroism spectroscopy, viscosity and cyclic voltammetry, and the modes of CT-DNA binding to the complexes have been proposed. Furthermore, DNA cleavage activities by the four complexes were performed in the presence and absence of external agents, the results indicate that their cleavage activities have been promoted in the presence of external agents. Mechanism investigation shows that the four complexes could cleave DNA through both oxidative and hydrolytic processes. In the four copper(II) complexes, complex 2 showed highest cleavage activity with the pseudo-Michaelis-Menten kinetic paraments k(cat)=5.16h(-1) and K(m)=3.6x10(-5)M.

Spin canting and slow relaxation in a 3D pillared nickel-organic framework.

A 3D nickel-organic framework formulated as {[Ni(2)(fum)(2)(bpt)(2)(H(2)O)] x 3 H(2)O}(n) (1), built from a mixed fumaric ion (fum), 1H-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt), and nickel salt, has been hydrothermally synthesized and characterized. Compound 1, having a Ni-fum chain structure in which the chains are pillared by the bpt spacers in a 3D brick-wall-like architecture, exhibits canted antiferromagnetism at 5.0 K. Below this temperature, slow relaxation is observed from the alternating-current susceptibility measurements corresponding to the spin-glass-like behavior.

Pillared cobalt–organic framework with an unprecedented (3,4,6)-connected architecture showing the coexistence of spin canting and long-range magnetic ordering

A novel (3,4,6)-connected 3D porous cobalt–organic framework formulated as {[Co2(Hbidc)2(bpt)2]·7H2O}n (1) (H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid, bpt = 1H-3,5-bis(4-pyridyl)-1,2,4- triazole) has been hydrothermally synthesized and characterized by X-ray diffraction analysis. Compound 1, having a Co-Hbidc layer structure in which the layers are pillared by the bpt spacers in a 3D architecture, exhibits the coexistence of spin-canted weak ferromagnetism with TN = 10 K and long-range magnetic ordering.

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 CoII/NiII/MnII/ZnII with 1,1′-biphenyl-2,2′-dicarboxylic acid and three positional isomeric ligands: structural diversity and properties

Hydrothermal reactions of 1,1′-biphenyl-2,2′-dicarboxylic acid (H2dpa) with Co(II), Ni(II) Mn(II) and Zn(II) salts, and systematically varied N-donor co-ligands (positional isomeric dipyridyl bridging ligands: 4,4′-bpt, 3,4′-bpt and 3,3′-bpt), lead to the formation of a series of supramolecular complexes, namely, [Co(dpa)(4,4′-bpt)(EtOH)(H2O)] (1), [Ni(dpa)(4,4′-bpt)(H2O)2]·2.5H2O (2), [Cu(dpa)(4,4′-bpt)(H2O)]·2H2O (3), [M(dpa)(3,4′-bpt)]·H2O (M = Co for 4, Ni for 5, Mn for 6, and Zn for 7, respectively), [Zn3(OH)2(dpa)2 (3,3′-bpt)2]·2H2O (8) (where 4,4′-bpt = 1H-3,5-bis(4-pyridyl)-1,2,4-triazole, 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). Structural analysis reveals that dpa manages the M(II) (M = Co, Ni, Mn and Zn) ions to form 1-D chains, which are further extended via the isomeric bpt connectors in different directions, to give rise to a variety of coordination polymers of 1–8. Magnetic susceptibilities of complexes 1–6 reveal the weak antiferromagnetic or ferromagnetic exchange interactions between the adjacent metal centers. Moreover, the luminescent properties of 7–8 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.