Syntheses, Crystal Structures, and Antibacterial Activity of New Tetranuclear Zinc(II) Complexes with Schiff Base Ligands.

Two new tetranuclear zinc(II) complexes, [Zn4(L1)2(µ2-η1:η1-CH3COO)4(µ1,1-N3)2] (1) and [Zn4(L2)4(CH3CH2OH)(H2O)] (2), where L1 and L2 are the deprotonated forms of 4-fluoro-2-((pyridin-2-ylmethylimino)methyl)phenol (HL1) and 4-fluoro-2-((2-(hydroxymethyl)phenylimino)methyl)phenol (H2L2), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy, and single crystal X-ray diffraction. X-ray crystal structural study indicated that the distances between the adjacent Zn atoms are 3.160(1)-3.353(1) Å in 1 and 3.005(1)-3.168(1) Å in 2. All zinc atoms in 1 are pentacoordinated in trigonal bipyramidal geometry, and those in 2 are in square pyramidal and octahedral geometry. The complexes and the Schiff bases were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.

Synthesis, Characterization and Crystal Structures of Zinc(II) and Cobalt(III) Complexes Derived from Tridentate NNO- and NON- Schiff Bases with Antibacterial Activities.

Two new polynuclear zinc complexes [Zn2Br2(L1)2] (1) and [Zn(µ1,5-dca)L2]n (2), and two new mononuclear cobalt(III) complexes [CoL1N3(Brsal)] (3) and [CoL2(HL2)] (4), where L1 = 5-bromo-2-(((2-dimethylamino)ethyl)imino)methyl)phenolate, L2 = 5-bromo-2-(((2-hydroxyethyl)imino)methyl)phenolate, dca = dicyanoamide, Brsal = 5-bromo-2-formylphenolate, have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, UV-Vis spectra, molar conductivity, and single crystal X-ray diffraction. X-ray analysis indicates that the Zn atoms in complex 1 are in distorted square pyramidal coordination, the Zn atoms in complex 2 are in distorted trigonal bipyramidal coordination, and the Co atoms in complexes 3 and 4 are in octahedral coordination. The molecules of the complexes are stacked through π···π interactions and hydrogen bonds. The complexes were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.

Synthesis, Characterization, X-Ray Crystal Structures and Antibacterial Activities of Oxidovanadium(V) Complexes with Hydrazone and Hydroxamate Ligands.

Two new oxidovanadium(V) complexes, [VOL1L] (1) and [VOL2L]·CH3OH (2·CH3OH), where L1 and L2 are the dianionic form of N'-(3-bromo-2-hydroxybenzylidene)picolinohydrazide (H2L1) and 2-chloro-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (H2L2), respectively, and L is the monoanionic form of 2-hydroxybenzohydroxamic acid (HL), were prepared and characterized by elemental analysis, infrared and electronic spectroscopy. Structures of the complexes were further confirmed by single crystal X-ray determination. The V atoms in the complexes are in octahedral coordination. The hydrazone ligands coordinate to the V atoms through the phenolate O, imino N, and enolate O atoms. The hydroxamate ligand coordinates to the V atom through the carbonyl and hydroxy O atoms. The complexes show effective antibacterial activity against B. subtilis, S. aureus and E. coli. The presence of Cl substitute group in the complex may enhance the antibacterial activity.

An ortho-rhom-bic polymorph of 1-benzyl-1H-benzimidazole.

The title compound, C(14)H(12)N(2), in contrast to the previously reported monoclinic polymorph [Lei et al. (2009 ▶). Acta Cryst. E65, o2613], crystallizes in the ortho-rhom-bic crystal system. The dihedral angle between the imidazole ring system and the phenyl ring is 76.78 (16)°. Weak C-H⋯N and C-H⋯π inter-actions are observed in the crystal structure.

1-Chloro-methyl-1H-1,2,3-benzotriazole.

In the title compound, C(7)H(6)ClN(3), the benzotriazole ring is essentially planar with a maximum deviation of 0.0110 (15)Å, and makes a dihedral angle of 0.46 (8)° with the benzene ring. In the crystal, mol-ecules are linked through inter-molecular C-H⋯N hydrogen bonds, forming chains along the c axis.

1-(Butan-2-yl-idene)-2-(2-nitro-phen-yl)hydrazine.

Crystals of the title compound, C(10)H(13)N(3)O(2), were obtained from a condensation reaction of butan-2-one and 1-(2-nitro-phen-yl)hydrazine. The mol-ecule exhibits a nearly coplanar structure, except for the methyl and methyl-ene H atoms, the largest deviations from the mean plane defined by all non-H atoms, except for the nitro group, being 0.120 (2) Šfor one of the nitro O atoms. Intra-molecular N-H⋯O hydrogen bonding helps to establish the mol-ecular configuration.

1-[4-(2-Fur-yl)but-3-en-2-yl-idene]-2-(2-nitro-phen-yl)hydrazine.

In the title Schiff base compound, C(14)H(13)N(3)O(3), the furan and benzene rings are oriented at a dihedral angle of 10.24 (13)°. Intra-molecular N-H⋯O hydrogen bonding is observed between the imino and nitro groups.

(E)-N'-(3,5-Dibromo-2-hydroxy-benzyl-idene)-2-nitro-benzohydrazide methanol solvate.

In the title compound, C(14)H(9)Br(2)N(3)O(4)·CH(3)OH, the Schiff base mol-ecule adopts an E geometry with respect to the C=N bond and the benzene rings are oriented at a dihedral angle of 45.3 (2)°. An intra-molecular O-H⋯N hydrogen bond helps to establish the conformation. In the crystal, the methanol solvent mol-ecule is linked to the Schiff base mol-ecule through an O-H⋯O hydrogen bond and inter-molecular N-H⋯O hydrogen bonds link the components to form layers parallel to the bc direction.

(E)-N'-(2-Hydr-oxy-3,5-diiodo-benzyl-idene)-2-nitro-benzohydrazide methanol solvate.

In the title compound, C(14)H(9)I(2)N(3)O(4)·CH(3)OH, the Schiff base mol-ecule adopts an E geometry with respect to the C=N bond and the dihedral angle between the benzene rings is 45.0 (2)°; an intra-molecular O-H⋯N hydrogen bond is present. In the crystal, adjacent Schiff base mol-ecules are linked by methanol solvent mol-ecules through inter-molecular N-H⋯O and O-H⋯O hydrogen bonds, forming dimers.

(E)-N'-(5-Chloro-2-hydroxy-benzyl-idene)-2-nitro-benzohydrazide.

In the title Schiff base compound, C(14)H(10)ClN(3)O(4), the mol-ecule adopts an E geometry with respect to the C=N bond and an intra-molecular O-H⋯N hydrogen bond is present. The benzene rings form a dihedral angle of 73.4 (2)°. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds occur.

N'-(2-Furylmethyl-ene)nicotinohydrazide.

The asymmetric unit of the title compound, C(11)H(9)N(3)O(2), contains two independent mol-ecules: the dihedral angles between the pyridine ring and the furyl ring are 17.00 (16) and 34.12 (15)°. The crystal structure involves inter-molecular C-H⋯O, N-H⋯N and N-H⋯O hydrogen bonds.

1-(But-2-enyl-idene)-2-(2-nitro-phen-yl)hydrazine.

The mol-ecule of the title Schiff base compound, C(10)H(11)N(3)O(2), adopts an E geometry with respect to the C=N double bond. The mol-ecule is roughly planar, with the largest deviation from the mean plane being 0.111 (2) Å, The enyl-idene-hydrazine group is, however, slightly twisted with respect to the phenyl ring, making a dihedral angle of 6.5 (3)°. An intra-molecular N-H⋯O hydrogen bond may be responsible for the planar conformation. An inter-molecular N-H⋯O hydrogen bond links two mol-ecules around an inversion center, building a pseudo dimer.

1-(2-Furylmethyl-ene)-2-(2-nitro-phen-yl)hydrazine.

The title Schiff base compound, C(11)H(9)N(3)O(3), was obtained from a condensation reaction of furan-2-carbaldehyde and 2-nitro-phenyl-hydrazine. The mol-ecule is roughly planar, the largest deviation from the mean plane defined by all non-H atoms being 0.097 (4). An in ntra-molecular N-H⋯O hydrogen bond might influence the planar conformation of the mol-ecule. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules, forming a chain.

2-Eth-oxy-4-{[(2-nitro-phen-yl)hydrazono]meth-yl}phenol.

The title compound, C(15)H(15)N(3)O(4), a Schiff base, was obtained from a condensation reaction of 3-eth-oxy-4-hydroxy-benzaldehyde and 2-nitro-phenyl-hydrazine. The mol-ecule is approximately planar, the largest deviation from the mean plane being 0.1449 (16) Å. An intramolecular N-H⋯O inter-action is also present. In the crystal, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules, forming chain parallel to the b axis.

[µ-1,1'-(Butane-1,4-di-yl)di-1H-benz-imidazole-κN:N]bis-{[N,N'-bis(car-boxy-meth-yl)ethyl-enediamine-N,N'-di-acetato-κO,O',O'',N,N']mercury(II)} methanol disolvate.

The binuclear title complex, [Hg(2)(C(10)H(14)N(2)O(8))(2)(C(18)H(18)N(4))]·2CH(3)OH, lies on an inversion center with the unique Hg(II) ion coordinated in a disorted octa-hedral environment with one Hg-N bond significantly shorter than the other two. In the crystal structure, inter-molecular O-H⋯O hydrogen bonds link complex and solvent mol-ecules into a three-dimensional network.

N'-[4-(2-Fur-yl)but-3-en-2-yl-idene]-iso-nicotino-hydrazide.

The mol-ecule of the title Schiff base compound, C(14)H(13)N(3)O(2), is not perfectly planar; the furyl and pyridine rings are twisted with respect to each other along the C(4)N(2)C(2) organic chain, making a dihedral angle of 13.3 (1)°. The occurence of N-H⋯O hydrogen bonds builds up a chain developing parallel to the c axis.

But-2-enal 2,4-dinitro-phenyl-hydrazone.

In the title compound, C(10)H(10)N(4)O(4), the but-2-enal chain is almost planar, the largest deviation from the mean plane being 0.013 (1) Å, and this plane makes a dihedral angle of 9.95 (24)° with the benzene ring,. Of the two nitro groups, one is twisted with respect to the benzene ring, making a dihedral angle of 5.7 (1)°, whereas the other is nearly in the plane of the benzene ring, with a twist angle of only 0.7 (1)°. This difference is related to the occurence of an intra-molecular N-H⋯O hydrogen bond with the O atom of the less twisted nitro group. The NH group is also involved in a weak inter-action with the same O atom of a symmetry-related mol-ecule, thus forming a pseudo inversion dimer.

N'-(But-2-enyl-idene)-iso-nicotino-hydrazide.

In the title Schiff base compound, C(10)H(11)N(3)O, the pyridine ring is twisted with respect to the mean plane containing the hydrazine chain, making a dihedral angle of 31.40 (9)°. The NH group inter-acts with the N atom of the pyridine ring through N-H⋯N hydrogen bonds to build up a zigzag chain developing parallel to the (01) plane.

Thio-phene-2-carbaldehyde 2,4-dinitro-phenyl-hydrazone.

In the approximately planar molecule of the title compound, C(11)H(8)N(4)O(4)S, the dihedral angle between the thio-phene and benzene rings is 5.73 (10)°. In the crystal structure, bifurcated inter/intra-molecular N-H⋯(O,O) hydrogen bonds are present. The intermolecular links lead to inversion dimers containing an R(2) (2)(12) graph-set motif.

3-(1,3-Benzodioxol-5-yl)-1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine.

In the title compound, C(25)H(19)NO(3), the oxazine ring displays a half-chair conformation. The fused benzene ring is nearly parallel to the naphthyl ring system, the dihedral angle between this benzene ring and the naphthyl system being 8.52 (11)°. The imino group is not involved in hydrogen bonding in the crystal structure.