Jin-Lei Tian

A novel 1,2,4-triazole-based copper(II) complex: synthesis, characterization, magnetic property and nuclease activity.

A novel binuclear copper(II) complex [Cu(2)L(mu-SO(4))](PF(6))(2) (1) (L=3,5-bis (bis(pyridine-2-ylmethyl)amino)methyl)-4H-1,2,4-triazol-4-amine) has been synthesized and structurally characterized. X-ray structure shows that the two copper(II) atoms are bridged by one bidentate sulfate ion and the 1,2,4-triazole ring of L with Cu1cdots, three dots, centeredCu2 distance of 4.404A. Each copper(II) center has a distorted trigonal-bipyramidal configuration. Variable-temperature magnetic susceptibility studies (2-300K) indicate the existence of weak antiferromagnetic coupling between the copper(II) ions in complex 1. The interaction of complex 1 with calf thymus DNA (CT-DNA) has been studied by UV absorption, fluorescence spectroscopy, circular dichroism spectroscopy, viscosity and cyclic voltammetry. Furthermore, complex 1 was able to promote single and double strand DNA cleavage in both aerobic and anaerobic conditions, the pseudo-Michaelis-Menten kinetic parameters k(cat)=2.58h(-1) and K(m)=1.2x10(-4)M were obtained for 1. The hydrolytic cleavage of DNA by the complex was supported by the evidence from free radical quenching, anaerobic experiment, thiobarbituric acid-reactive substances (TBARS) assay.

Synthesis, DNA binding, photo-induced DNA cleavage, cytotoxicity and apoptosis studies of copper(II) complexes.

Two new Cu(II) complexes, [Cu(acac)(dpq)Cl] (1) and [Cu(acac)(dppz)Cl] (2) (acac = acetylacetonate, dpq = dipyrido[3,2-d:20,30-f]quinoxaline, dppz = dipyrido[3,2-a:20,30-c] phenazine), have been synthesized and their DNA binding, photo-induced DNA cleavage activity and cell cytotoxicity are studied. The complexes show good binding propensity to calf thymus DNA in the order: 2(dppz) >1(dpq). Furthermore, two complexes exhibit efficient DNA cleavage activity on natural light or UV-A (365 nm) irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. The photo-induced DNA cleavage activity of the dppz complex 2 is found to be more efficient than its dpq analogue. In vitro study of the photocytotoxicity of two complexes on HeLa cells indicate that both of them have the potential to act as effective anticancer drugs, with IC(50) values of 5.25±0.83 μM (1) and 4.40±0.52 μM (2) in the natural light, and 2.57±0.92 μM (1) and 2.18±0.52 μM (2) in UV-A light. In addition, to detect an apoptotic HeLa body, cells were stained with Hoechst 33342 dye.

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.

Two water-soluble copper(II) complexes: synthesis, characterization, DNA cleavage, protein binding activities and in vitro anticancer activity studies.

Two water-soluble ternary copper(II) complexes of [Cu(L)Cl](ClO4) (1) and [Cu(L)Br2] (2) (L=(2-((quinolin-8-ylimino)methyl)pyridine)) were prepared and characterized by various physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square-pyramidal CuN3Cl2 (1) or CuN3Br2 (2) geometry in which Schiff-base L acts as a neutral tridentate ligand. Both complexes present intermolecular π-π stacking interactions between quinoline and pyridine rings. The interaction of two complexes with CT-DNA (calf thymus-DNA) and BSA (bovine serum albumin) was studied by means of various spectroscopy methods, which revealed that 1 and 2 could interact with CT-DNA through intercalation mode, and could quench the intrinsic fluorescence of BSA in a static quenching process. Furthermore, the competition experiment using Hoechst 33258 indicated that two complexes may bind to CT-DNA by a minor groove. DNA cleavage experiments indicate that the complexes exhibit efficient DNA cleavage activities without any external agents, and hydroxyl radical (HO) and singlet oxygen ((1)O2) may serve as the major cleavage active species. Notably, the in vitro cytotoxicity of the complexes on three human tumor cells lines (HeLa, MCF-7, and A549) demonstrates that two compounds have broad-spectrum antitumor activity with quite low IC50 ranges of 0.43-1.85μM. Based on the cell cycle experiments, 1 and 2 could delay or inhibit cell cycle progression through the S phase.

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, structure, and DNA binding of three reduced amino-acid Schiff-base zinc(II), nickel(II), and cadmium(II) complexes

Three new reduced amino-acid Schiff-base complexes, [Zn(HL)2] · H2O (1), [Ni(HL)2] · H2O (2), and [Cd(HL)2] · H2O (3), where H2L is a reduced Schiff base derived from condensation of N-(2-hydroxybenzaldehyde) and L-histidine, have been synthesized and characterized by elemental analysis, UV-Vis absorption spectra and single crystal X-ray diffraction. Complexes 1–3 are isostructural. All metal centers are six-coordinate with O2N4 donor sets in slightly distorted octahedra. Unlike its Schiff-base counterpart, the deprotonated monoanionic ligand HL− has a more flexible backbone and two HL− are tridentate to one metal. Moreover, the binding interactions of these complexes with calf thymus DNA (CT-DNA) have been investigated by UV-Vis spectra and fluorescence quenching, which show that the complexes bind in an intercalative mode.

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.

Syntheses, structures and properties of two one-dimensional chain complexes: [Mn(Hpdc)(H2O)2]n and [Cu2(Hpdc)2][4,4′-dpdo] (Hpdc=3,5-pyrazoledicarboxylic acid group, dpdo=4,4′-dipyridyl-N,N′-dioxide hydrate)

Abstract Two one-dimensional chain complexes: [Mn(Hpdc)(H2O)2]n (1) and [Cu2(Hpdc)2][4,4′-dpdo] (2) have been synthesized from hydrothermal solutions at 150 °C. Both structures are mainly constructed by a single multifunctional ligand, monopotassium 3,5-pyrazoledicarboxylate (KH2pdc). All metal atoms are six-coordinated in 1, two kinds of carboxylic bridges are found between manganese atoms to form a one-dimensional chain and further construct three-dimensional structure by hydrogen bonds. In 2, all copper atoms are five-coordinated, Cu1 and Cu1A are linked by the nitrogen atoms in the pyrazole ring to form a dimmer and two-dimensional structure is formed by weak coordination bonds and hydrogen bonds. Susceptibility data of 1 and 2 show antiferromagnetic coupling interactions.

Synthesis, DNA binding, photo-induced DNA cleavage and cell cytotoxicity studies of a family of light rare earth complexes

A family of light rare earth complexes, [RE(acac)(3)(dpq)] (RE=La (1), Ce (2), Pr (3), Nd (4), Sm (5)) and [RE(acac)(3)(dppz)].CH(3)OH (RE=La (6), Ce (7), Pr (8), Nd (9), Sm (10) viz. acetylacetonate (acac), dipyrido[3,2-d:20,30-f]quinoxaline (dpq), dipyrido[3,2-a:20,30-c] phenazine (dppz)), have been synthesized and structurally characterized. Binding interactions of these complexes with CT-DNA and their photo-induced DNA cleavage activity with pBR 322 DNA are also investigated. These complexes have strong DNA binding interaction (K(b)≈10(5)M(-1) and K(app)≈10(5)M(-1))and the binding propensity to CT-DNA decrease with the order: dppz complexes>dpq complexes. Furthermore, DNA photocleavage experiments indicate that these complexes are efficient DNA cleaving agents in UV-A (365 nm) and ambient light in the absence of any external reagents. Hydroxyl radical (HO(•)) and singlet oxygen ((1)O(2)) are the major cleavage active species from the machanistic studies. Moreover, cell cytotoxicity studies of these complexes on HeLa, K562 and MDA-MB-231 cells indicate that they have the potential to act as effective metal-based anti-cancer drugs.

Hydrolytic cleavage of double-strand DNA by the water-soluble dicobalt (III) complexes of 1,4,7-Triazacyclononane-N-acetate

Three water-soluble dicobalt(III) complexes, [Co(2)L(2)(micro-OH)(2)](ClO(4))(2).5H(2)O (1), [Co(2)L(2)(micro-OH)(2)](ClO(4))(2).CH(3)OH.H(2)O(2); [Co(2)L(2)(micro-OH)(2)](ClO(4))(2).4H(2)O(3) (L=1,4,7-triazacyclononane-N-acetate monoanion), were prepared to serve as nuclease mimics. The complexes were characterized by X-ray, IR and UV-vis spectroscopy as well as ESI-MS. Three complexes exhibit similar structures, just with different solvent molecules. The electrospray mass spectrum of 1 in solution indicates that dinuclear ion [Co(2)L(2)(micro-OH)(2)-H(+)] (+) (4) is the active species. In the absence of any reducing agent, the complexes cleave plasmid pBR322 DNA was performed and its hydrolytic mechanism was demonstrated with radical scavengers, anaerobic reaction and T4 ligase. The kinetic aspects of DNA cleavage under pseudo- or true-Michaelis-Menten conditions are also detailed, kinetic parameters (k(cat), K(M)) were calculated to be 3.57 h(-1), 6.92 x 10(-4)M; 0.28 h(-1), 1.9 x 10(-5)M for 4, respectively.