Dong-Mei Xian

Synthesis and Structures of Halo-Substituted Aroylhydrazones with Antimicrobial Activity

A series of new halo-substituted aroylhydrazones have been prepared and structurally characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectra, and single crystal X-ray diffraction. The compounds were evaluated for their antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescence) and antifungal (Candida albicans and Aspergillus niger) activities by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method. Among the tested compounds, N′-(2-chloro-5-nitrobenzylidene)-2-fluorobenzohydrazide showed the most effective antimicrobial activity with minimum inhibitory concentration values of 0.82, 2.5, 1.7, 15.2, and 37.5 μg mL–1 against B. subtilis, S. aureus, E. coli, P. fluorescence, and C. albicans, respectively. The biological assay indicated that the presence of the electron-withdrawing groups in the aroylhydrazones improved their antimicrobial activities.

Two lantern-like 1D polymeric Schiff base copper(I/II) complexes derived from copper(II) salts containing rarely seen [CuI(NCS)4] bridges

Two lantern-like 1D polymeric Schiff base copper(I/II) complexes containing rarely seen [CuI(NCS)4] bridges have been obtained by reaction of tridentate Schiff bases, copper(II) salts, and ammonium thiocyanate in methanol under mild condition.

Preparation and structural characterization of oxovanadium(V) complexes with Schiff bases and their inhibition studies on Helicobacter pylori urease

A series of structurally similar dinuclear oxovanadium(V) complexes, [VO2L]2 (L = L1 = 2-[(2-methylaminoethylimino)methyl]phenolate (1); L = L2 = 2-[(2-ethylaminoethylimino)methyl]phenolate (2); L = L3 = 2-[(2-isopropylaminoethylimino)methyl]phenolate (3)), has been synthesized and characterized by physico-chemical methods and single-crystal X-ray diffraction. The V in each complex is octahedral, with three donors of L and one oxo defining the equatorial plane, and with two oxos occupying the axial positions. The complexes were tested for their urease inhibitory activities. The inhibition rate (%) of 1, 2, and 3 at 100 µmol L−1 on urease are 67 ± 1, 53.5 ± 0.9, and 44 ± 1. The relationship between structures of the complexes and the urease inhibitory activities indicates that shorter terminal groups of the complexes have stronger activities against urease. Molecular docking study of the complexes with the Helicobacter pylori urease was performed.

Synthesis, biological evaluation, and molecular docking studies of 2,5-substituted-1,4-benzoquinone as novel urease inhibitors.

A series of 2,5-substituted-1,4-benzoquinone (1-6) were prepared and structurally characterized by elemental analysis, IR spectra, (1)H and (13)C NMR spectra, and single crystal X-ray determination. The urease inhibitory activities of the compounds against H. pylori urease were studied. Among the compounds, 2,5-bis(2-morpholin-4-ylethylamino)-[1,4]benzoquinone (2) shows the most effective activity with IC(50) value of 27.30 ± 2.17 μM. Docking simulation was performed to insert compound 2 into the crystal structure of H. pylori urease at the active site to determine the probable binding mode. As a result, compound 2 may be used as a potential urease inhibitor.

Dinuclear Schiff-base copper(II) complexes with various bridging groups

Three new centrosymmetric dinuclear copper(II) complexes, [Cu2Cl2(L1)2] (1), [Cu2(μ 1,3-NCS)2(L2)2] (2), and [Cu2(μ 1,1-N3)2(L3)2] (3), where L1, L2, and L3 are the deprotonated forms of the Schiff bases 1-[(2-propylaminoethylimino)methyl]naphthalen-2-ol (HL1), 1-[(3-methylaminopropylimino)methyl]naphthalen-2-ol (HL2), and 2-[(2-isopropylaminoethylimino)methyl]phenol (HL3), respectively, have been prepared and characterized by elemental analysis, IR spectra, and single-crystal X-ray crystallography. Each Cu is coordinated by the three donors of the Schiff bases and by two bridging groups, forming a square-pyramidal geometry.

Synthesis, structures, and fluorescence of azido-bridged dinuclear and thiocyanato-bridged tetranuclear cadmium(II) complexes derived from N-isopropyl-N′-(1-pyridin-2-ylethylidene)ethane-1,2-diamine

A new azido-bridged dinuclear cadmium(II) complex [Cd2L2(μ 1,1-N3)2(ONO2)2] (1) and a new thiocyanato-bridged tetranuclear cadmium(II) complex [Cd4L4(μ 1,3-NCS)4(NCS)4] (2), where L is the tridentate Schiff base N-isopropyl-N′-(1-pyridin-2-ylethylidene)ethane-1,2-diamine, were prepared and characterized. X-ray single crystal structure determination reveals that 1 is a centrosymmetric end-on azido-bridged dinuclear cadmium(II) compound and 2 is a rarely seen centrosymmetric end-to-end thiocyanato-bridged tetranuclear cadmium(II) compound. Cd in each complex is in distorted octahedral coordination. In the crystal structure of 1, the dinuclear cadmium(II) molecules are linked through N–H ··· O hydrogen bonds to form a 3-D network. In the crystal structure of 2, the tetranuclear cadmium(II) complex molecules are linked through N–H ··· S hydrogen bonds to form 1-D chains. The thermal stability and preliminary fluorescence properties of the complexes were investigated.

The anion-directed self-assembly of manganese complexes derived from 2-ethoxy-6-[(2-phenylaminoethylimino)methyl]phenol

The mixed valence manganese(II/IV) complex, [MnIIL2(MeOH)2]·[MnIVL2(OAc)2]·2(MeOH) (1), and the chloride-bridged 1D polymeric manganese(III) complex, [MnIIIL2(μ-Cl)]n (2), where L is the deprotonated form of 2-ethoxy-6-[(2-phenylaminoethylimino)methyl]phenol (HL), have been prepared and structurally characterized by single-crystal X-ray diffraction analysis and IR spectra. The Mn atoms in both complexes are octahedrally coordinated. The self-assembly of the complex structures is apparently directed by the anions of the manganese salts.

Syntheses and Crystal Structures of Copper(II) and Nickel(II) Complexes With Schiff Bases: Nickel(II) Induced Cleavage of the C–N Bonds

Three centrosymmetric mononuclear copper(II) and nickel(II) complexes, [Cu(MMP)2] (1), [Ni(IMP)2] (2), and [Ni(IEP)2] (3) (MMP = 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl] phenolate, IMP = 2-iminomethyl-5-methoxyphenolate, IEP = 2-(1-iminoethyl)phenolate), have been prepared from similar tridentate Schiff bases derived from 2-morpholin-4-ylethylamine with 4-methoxysalicylaldehyde and 2-acetylphenol, respectively. The complexes were characterized by elemental analysis, infrared spectra, and single-crystal X-ray diffraction. The Cu and Ni atoms in the complexes are in square planar coordination. The Ni2+ ion may play an important role for the cleavage of the C–N bonds of the Schiff base ligands.

Synthesis and Crystal Structure of a Rarely Seen Terephthalato-Bridged Dinuclear Copper(II) Complex [Cu2(CMP)2(TPA)]·[Cu2(CMP)2(MeOH)2(TPA)]·2H2O

A rarely seen terephthalato-bridged dinuclear copper(II) complex, [Cu2(CMP)2(TPA)]·[Cu2(CMP)2(MeOH)2(TPA)]·2H2O (CMP = 4-chloro-2-[(2-isopropylaminoethylimino)methyl]pheno- late, TPA = terephthalate), has been prepared and characterized by elemental analysis, infrared spectrum, and single crystal X-ray determination. The complex crystallizes in the triclinic space group P–1, with a = 9.741(1) Å, b = 11.248(2) Å, c = 17.659(2) Å, α = 95.915(2)°, β = 90.656(2)°, γ = 111.747(2)°, V = 1785.0(4) Å3, Z = 1, GOOF = 1.033, R 1 = 0.0432, and wR 2 = 0.1109. The asymmetric unit of the complex contains two centrosymmetric terephthalato-bridged dinuclear copper(II) molecules and two water molecules of crystallization. The Cu atoms in one molecule are in square planar coordination, and in the other one are in square pyramidal coordination. Supplemental materials are available for this article. Go to the publishers online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.

The Unexpected Synthesis, Crystal Structure, and Thermal Stability of a Copper(II) Complex Derived from 2-[(2-Phenylaminoethylimino)methyl]benzoic Acid

A new mononuclear copper(II) complex, [Cu(PIBA)2(OH2)], where PIBA is the anionic form of 2-(1-phenylimidazolidin-2-yl)benzoic acid, has been unexpectedly obtained from the reaction of 2-formylbenzoic acid, N-phenylethane-1,2-diamine, and copper perchlorate in methanol. The complex was characterized by elemental analysis, infrared spectrum, and single-cyrstal X-ray diffraction. The complex crystallizes in the triclinic space group P–1, with unit cell dimensions a = 11.812(2) Å, b = 11.884(2) Å, c = 22.799(3) Å, α = 89.168(2)°, β = 87.290(2)°, γ = 88.604(2)°, V = 3195.5(10) Å3, Z = 4, R 1 = 0.0775, and wR 2 = 0.1647. The Cu atom in the complex is five-coordinated in a square pyramidal geometry by two carboxylate O and two imidazolidine N atoms from two PIBA ligands, and by one water O atom. The thermal stability of the complex has also been determined.