Syntheses,Crystal Structures and Antibacterial Activities of Schiff Base Ligand and Its Nickel(Ⅱ) Complex

A complex [NiL2] was synthesized, in which L, or to be exact, a Schiff base ligand(HL), was derived from the condensation of 1-phenyl-3-methyl-4-phenylacetyl-5-pyrazolone(PMPAP) with L-phenylalanine methyl ester. They were characterized by IR and single-crystal X-ray diffraction. Green block crystals of both ligand and its complex were grown at room temperature. The ligand, which consists of two individual fragments, crystalizes in the P1 space group(a = 5.6268(5), b = 10.6892(11) and c = 19.4869(18) ). The complex crystalizes in the P21 space group(a = 21.4076(18), b = 9.4792(8) and c = 25.287(2) ), which consists of a nickel six-coordinated compound. Every fragment is a distorted octahedron with four oxygen and two nitrogen atoms. The Schiff base ligand(HL) and its complex have been tested in vitro to evaluate their antibacterial activity against bacteria Escherichia Coli and Bacillus subtilis. It is found that the complex has higher activity than the corresponding free Schiff base ligand(HL) against the same bacterial.     

Synthesis, Structure and Properties of Tren-Schiff Base Compound and Its Manganese(III) Complex by Original Self-assembly Reaction

The new self-assembly tripodal hexadentate Schiff base compound, C 27 H 30 N 4 O 3 , derived from tris(2-aminoethyl)amine(tren) with salicylaldehyde and its manganese(III) complex [(C 27 H 27 N 4 O 3 )Mn]·CH 3 OH(1) were designed and synthesized by original self-assembly reaction at room temperature in the solution of methanol. Both the compounds were characterized by elemental analysis, IR spectrometry, UV-Vis spectroscopy and X-ray sin-gle crystal diffraction. It is noteworthy that the tripodal hexadentate Schiff base ligand effectively encapsulates the manganese(III) ion and enforces a six-coordinate geometry in complex 1 with the apical nitrogen atom of tren-Schiff base remaining unbound to the metal. It is found that there are several intra-molecular hydrogen bonds in them(C—H···O and O—H···N). In addition, quantum chemistry calculations were also performed and discussed in detail. These results are consistent with the structural analyses of them.     

非对称N-(亚水杨基)二亚乙基三胺铜(Ⅱ)配合物的合成、结构分析和催化活性评价(英文)

A new copper(Ⅱ) complex of a non‐symmetric Schiff base, [CuII(saldien)(H2O)]+(1), has been synthesized and characterized by elemental analysis and several other spectroscopic methods (Hsaldien = N‐(salicylidene)diethylenetriamine). The crystal structure of 1 has also been determined by X‐ray crystallography. The geometry of the complex cation in 1 was found to be distorted square pyramidal with the mononegative Schiff base coordinating to the copper in a tetradentate mode via the O,N,N’, and N’’‐donor atoms. The remaining coordination site was occupied by the O atom of a H2O molecule in the axial position. The catalytic potential of 1 was tested in the oxidation reactions of cyclooctene and cyclohexene with aqueous 30% H2O2/NaHCO3 in acetonitrile. These reactions proceeded smoothly to give the corresponding epoxides with selectivity levels greater than 99%. This catalytic system also showed high levels of activity and selectivity towards the oxidation of cyclohexane (i.e., cyclohexanol 37% and cyclohexanone 54%) in comparison with most of the other Cu‐based systems reported in the literature.     

Synthesis, Crystal Structure and Properties of Complex VO（C10H9NO3） （C13H10NO2）

Complex VO(C10H9NO3)(C13H10NO2)(C10H9NO2-3=N-salicylidene-L-alaninate, C13H10NO-2=N-phenylbenzohydroxamate) was synthesized and characterized by means of elemental analysis, IR, UV, 1H NMR spectroscopies, cyclic voltammetry and single crystal X-ray diffraction. The complex crystallized in a monoclinic system with space group P21 and crystal cell parameters a=0.9720(1) nm, b=1.8274(2) nm, c=1.2542(1) nm, β=104.868(9)°, V=2.1532(4) nm3, Mr=470.34, Z=2. The two oxygen atoms and the one nitrogen atom of the tridentate Schiff base ligand and the one oxime oxygen atom of the hydroxamate ligand coordinate to the vanadium atom, forming an equatorial plane, the two axial positions are respectively occupied by the oxygen atom of the oxovanadium and the carbonyl oxygen atom of the hydroxamate and the vanadium atom exhibits a distorted octahedral VO(ONO)(OO) coordination sphere. The 1H NMR spectrum suggests that the two isomers, endo and exo in a molar ratio of 1/1.7, coexist in the solution of the title complex in CDCl3. There exists a quasi-reversible one-electron redox reaction corresponding to VⅤ/VⅥ couple in the three non-aqueous solvents, and the redox potential E1/2 of the title complex substantially shifts in the direction of the positive voltage increase in the order: CH2Cl2＜CH3CN＜DMF.     

Stereocontrol of the Schiff Base of Substituted Benzaldehyde to Staudinger Cycloaddition Reaction

Syntheses of 4 novel chiral azetidin-2-one derivatives,which were characterized by ^1H NMR,IR,specific rotation and elemental analysis,through Staudinger cycloaddition reaction of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring,were described.For the first time,this type of 3S,4R configuration azetidin-2-one monocrystals with many chiral centers [(3S,4R)-3-hydroxy-N-[(S)-(1-phenyl)ethyl]-4-(2‘‘-chlorophenyl)-azetidin-2-one monocrystal]were obtained,the structures of which were determined by X-ray diffraction analysis.The effects of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring on stereoselectivity of Staudinger cycloaddition reaction products were discussed and the results are showed as below:2-chlorophenyl Schiff base favored to yield 3S,4R configuration product,but 4-chlorophenyl Schiff base favored to yield 3R,4S configuration product.The reaction orientation of 2,4-dichlorophenyl Schiff base was determined by corporate effect of 2- and 4-chlorine,and that of the 4-chlorine was more obvious.In contrast to 4-chlorophenyl,although the main product was 3R,4S configuration,3-chlorophenyl owned lower selectivity.     

A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors： Synthesis of N-4-Methoxybenzylidene-2-（3-hydroxyphenylazo）-5-hydroxyaniline and Its Nickel（Ⅱ） Complex

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxyphenylamine （SB） derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel（Ⅱ） complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio （M ： L = 1 ： 2） and suggested a square planar geometry for the complex.     

A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors: Synthesis of N-4-Methoxy- benzylidene-2-(3-hydroxyphenylazo)-5-hydroxy- aniline and Its Nickel(II) Complex

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxy- phenylamine (SB) derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel(II) complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio (M∶L＝1∶2) and suggested a square planar geometry for the complex.     

Synthesis,structural characterization and antibacterial activity of diorganotin(Ⅳ) complexes with ONO tridentate Schiff bases containing pyridine ring

Five organotin（IV） complexes,were obtained by reaction of SnR₂Cl₂（R = Ph,Me,Bu） with ONO donor Schiff bases.The synthesized complexes have been investigated by elemental analysis and IR,¹H NMR,and ¹¹⁹Sn NMR spectroscopy.These data show that the Schiff base acts as a tridentate dianionic ligand and coordinates via the imine nitrogen and two oxygen atoms.The Xray crystallography of complex 4 shows a dimeric structure for this molecule.The in vitro antibacterial activities of the Schiff bases and their complexes have been evaluated against Gram-positive（Bacillus subtilis and Staphylococcus aureus） and Gram-negative （Escherichia coli and Pseudomonas aeruginosa） bacteria and compared with the standard antibacterial drugs.     

Syntheses, Characterizations, Crystal Structures and Antibacterial Activities of Two Zinc(II) Complexes with a Schiff Base Derived from o-Vanillin and p-Toluidine

Two new zinc(II) complexes, [Zn2L2Cl4]·2[ZnL(CH3OH)Cl2] 1 and [ZnL2(NO3)2] 2, were synthesized by reacting ZnX2·nH2O (X = Cl-, NO3-) and a Schiff base ligand 2-[(4-me- thylphenylimino)methyl]-6-methoxyphenol (C15H15NO2, L) which was obtained by the condensation of o-vanillin (2-hydroxy-3-methoxybenzaldehyde) with p-toluidine. Both 1 and 2 were characterized by single-crystal X-ray diffraction technique, elemental analysis, molar conductance, FT-IR, UV-Vis, 1H-NMR spectra and thermogravimetric analysis. The Schiff base ligand and its zinc(II) complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia Coli, Staphylococcus aureus and Bacillus Subtilis. The results show that these complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.     

SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITY OF N,N‘-BIS(3-ALLYL SALICYLIDENE)ETHYLENEDIAMINE COBALT(II) SCHIFF BASE COMPLEX ANCHORED ON A NEW POLYMER SUPPORT

A new chelating polymer support has been prepared by suspension copolymeriz a tion of synthesized N,N‘-bis(3-allyl salicylidene)ethylenediamine monomer Schiff base (N,N‘-BSEDA) with styrene (St) and divinylbenzene (DVB) using azobisisobutyronitrile (AIBN) as initiator in the presence of poly(vinyl alcohol). The content and complexation ability of monomer Schiff base (N,N‘-BSEDA) for cobalt(II) ions in prepared crosslinked polymer beads have shown dependence on the amount of DVB used in reaction mixture. The amount of monomer Schiff base (N,N‘-BSEDA) in crosslinked beads showed a substantial decreasing trend at high concentration of DVB in the reaction mixture (＞ 1.5 mol dm-3), hence the efficiency of complexation (EC%) and cobalt(II) ion loading (EL%) of polymer beads showed a decreasing trend. The structure of monomer Schiff base (N,N‘-BSEDA) and its cobalt(II) complex on polymer support was elucidated by IR, UV and magnetic measurements. The catalytic activity of polymer bound cobalt(Ⅱ) Schiff base complex was evaluated by analyzing kinetic data of decomposition of hydrogen peroxide in the presence of either supported cobalt (II) complex or free cobalt(II) complex. The activation energy for the decomposition of hydrogen peroxide by polymer supported cobalt(II)complex was found to be low (33.37 kJ mol-l) in comparison with unsupported cobalt(II) complex (56.35 kJ mol-1). On the basis of experimental observations, reaction steps are proposed and a suitable rate expression derived.     

Synthesis,Crystal Structure,and Thermal Stability of a Dibutyltin Complex {[4-Et2NC6H3（O）C=NC6H3（O）- 5-NO2]（n-Bu2Sn）}2 and Its Interaction with DNA

The Schiff base organotin(IV) complex {[4-Et2NC6H3(O)C=NC6H3(O)-5-NO2](nBu2Sn)}2 has been synthesized via the reaction between 4-(diethylamino) salicylaldehyde-2-amino-4-nitrophenol Schiff base(H2L) and dibutyltin oxide. Complex C1 has been characterized by IR, 1H NMR, 13 C NMR spectra, and elemental analysis, and its crystal structure was determined by X-ray diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 15.6559(8), b = 9.1657(5), c = 18.8351(10) , β = 107.3440(10)°, Z = 4, V = 2579.9(2) 3, Dc = 1.442 Mg·m-3, μ(MoKα) = 1.025 mm-1, F(000) = 1152, R = 0.0250 and wR = 0.0633. The central Sn atom is coordinated in a hexadentate manner to assume a distorted octahedral configuration. Complex C1 was studied by TGA analysis in air atmosphere. The interaction between complex C1 and the herring sperm DNA was realized through the intercalation of the complex based on the studies by EB fluorescent probe.     

Copolymer of lactide and ε-caprolactone catalyzed by bimetallic Schiff base aluminum complexes

A series of copolymers of lactide(LA) and e-caprolactone(ε-CL) with different monomer feed ratios were achieved using three kinds of bimetallic Schiff aluminum complexes as catalysts. The ratios of LA and ε-CL units in different copolymers and the average segments length were determined by NMR analysis. The comparative kinetic study of L-LA/ε-CL and rac-LA/ε-CL copolymerization systems showed that the polymerization rate of LA was faster than ε-CL, and L-LA showed polymerization rate slightly faster than rac-LA. It was inferred that the copolymers achieved by these complexes were gradient copolymers with gradual change in distribution of LA and e-CL units. The thermal properties of these copolymers were characterized by DSC analysis, which showed that the glass transition temperature(Tg) of these copolymers changed regularly according to the pro-portion change of two structural units.     

–ONNO–四齿配体负载铜(Ⅱ)配合物的合成与结构研究:环二酯开环聚合的高效催化剂(英文)

The –ONNO– tetradentate Schiff base ligand N,N'-bis(2-hydroxy-3- methoxybenzaldehyde) benzene-1,2-diamine(HMBBD) has been synthesized. The ligand was attached to copper(Cu-HMBBD) in methanol under N_2 atmosphere to give a mononuclear complex. The reactivity of this complex in the ring-opening polymerization(ROP) of lactide has been studied. The complex has a square planner geometry, as determined by X-ray diffraction studies. The copper complex is highly active towards the ring-opening polymerization of lactide, and the rate of polymerization is heavily dependent on the initiator used. The copper complex allows controlled ring-opening polymerization, as shown by the linear relationship between the percentage conversion and the number average molecular weight. Based on the literature, a mechanism for the ROP of lactide has been proposed.     

Synthesis, Spectroscopic Properties and Crystal Structures of Dibenzyltin（IV） Dithiobenzoate and Chlorodibenzyltin（IV） Thiobenzoate

Two dibenzyltin(IV) complexes with thiobenzoate ligand, (PhCH2)2Sn(SOCPh)2 (1) and (PhCH2)2Sn(C1)SOCPh (2), have been synthesized by the reaction of dibenzyltin(IV) dichloride with thiobenzoic acid in the presence of organic base Et3N and characterized by IR, ^1H NMR spectroscopy and elemental analysis. Their crystal structures were determined by X-ray single crystal diffraction analysis. In the crystals of 1, the tin atom is six-coordinated in a distorted octahedron configuration. In the crystals of 2, the molecular packing in unit cell reveals that the two adjacent molecules are symmetrically linked to each other to form a dimer with intermolecular Sn…C1 distances of 0.3591 (2) nm and the tin atom is five-coordinated in a distorted trigonal bipyramid configuration.     

丙酮酸异烟酰腙四核有机锡配合物的合成、表征及{[nBu2Sn(C9H8N3O3)O]SnBu3n}2的晶体结构

The tetranuclear alkyltin(Ⅳ) compounds {[R2Sn(C9H8N3O3)O]SnR3}2 [R=n-Bu (1), 4-CNC6H4CH2 (2),C6H5CH2 (3), 4-ClC6H4CH2 (4)] were prepared by the reaction of Schiff base ligand pyruvic acid isonicotinyl hydrazone with (R3Sn)2O in the corresponding molar ratio of 1:1. All compounds have been characterized by elemental analysis, IR and ^1H NMR spectra. The crystal structure of compound 1 was determined by X-ray single crystal diffractional analysis. This compound exhibits a dimeric structure containing distannoxane units with two types of the tin atoms. For the first tin atom, it appears to be seven-coordinated with a distorted pentagonal bipyramid geometry, and the other is five-coordinated with a distorted trigonal bipyramidal geometry. The molecules are packed in the unit cell in two-dimensional network structure through an interaction between the N atoms of the pyridine and the tin atoms of an adjacent molecule.     

Synthesis, Crystal Structure, and Cytotoxic Property of Di（μ1”,1”-azide）bis（4-nitro-2-（3＇-dimethylaminon-propylimino）methylenephenolate）dizinc（Ⅱ）

The title azide-bridged dinuclear Schiff base zinc(Ⅱ) complex [Zn2(C12H16N3O3)2-(μ1,1-N3)2] was prepared and characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group F21/n with a = 8.736(2), b = 14.850(3), c = 11.775(2) (A), β = 102.42(3)°, V= 1491.8(5) (A)3, Z= 2, Dc = 1.593 g/cm3, Mr = 715.36, λ(MoKα) = 0.71073 (A), μ = 1.669 mm-1, F(000) = 736, the final R = 0.0338 and wR = 0.0789. A total of 3411 unique reflections were collected, of which 2777 with Ⅰ＞2σ(Ⅰ) were observed. The molecule of the complex is located on a crystallographic inversion centre. Each Zn atom in the complex is five-coordinated by one Schiff base ligand and two bridging azide groups, forming a trigonal bipyramidal configuration. The Zn…Zn distance is 3.328(2) (A). In the crystal structure, molecules are linked through intermolecular C-H…N hydrogen bonds, forming layers parallel to the bc plane. The complex shows low cytotoxic property to both normal and carcinoma cells.     

Novel π-Conjugated Poly（Schiff base） Containing Thiazole and Tetrathiatetrahyd ropentalene Moieties

A new kind of π-conjugated heterocyclic poly(Schiff base) was firstly prepared by the condensation reaction between tetrathiatetrahydropentalene-type diketone and bithiazole-diamine in good yields. The polymers were characterized by VPO, FTIR and ^1H NMR spectroscopy. A large bathochromic shift was observed in UV-Vis spectra for these polymers due to the π-π* transition in the conjugated main chain. Brief examination indicated that the nitrogen-and sulfur-containing polymers exhibited an excellent chelating tendency to metal ions and the corresponding polymeric complexes would be expected to have potential in applications.     

Rare earth complexes with noncyclic polyether-methionine Schiff base

A novel Schiff base (TAMET) was synthesized by the condensation of tetraglycol aldehyde with methionine and a mild oxidant CrO3· (C5H5N)2 was selected for the reaction. Seven new rare earth complexes with this Schiff base have been synthesized and characterized by elemental analysis, TG-DTA, molar conductivity, magnetic susceptibility and IR, especially 1H NMR spectra. Information was obtained from reflectance spectra and the coordination of sulfur atom to rare earths was discussed. The experimental results show that thesecompounds have some biological activity and could dispose of O2.     

Catalytic Oxidative Decarboxylation of Some Benzylcarboxylic Acid Derivatives by a New Iron(III) Schiff Base Complex

A quadridentate Schiff base ligand of N,N’-bis(2-hydroxy-α-methylbenzylidene)ethylenediamine (HMBEDA) and its new iron(III) complex were synthesized and identified by analytical, spectral data (1H NMR, 13C NMR FT-IR and UV-visible) and molar conductance. A rapid and efficient homogeneous oxidative decarboxylation of some benzylcarboxylic acid derivatives was carried out by a catalytic amount of iron(III) Schiff base complex in chloroform, using tetrabutylammonium periodate as a mild oxidant in good to excellent yields at room temperature.     

Syntheses, Characterizations, Crystal Structures and Antibacterial Activities of Two Zinc（II） Complexes with a Schiff Base Derived from o-Vanillin and p-Toluidine

Two new zinc（Ⅱ） complexes, [Zn2L2Ch].2[ZnL（CH3OH）Cl2] 1 and [ZnL2（NO3）2] 2, were synthesized by reacting ZnX2.nH2O （X = Cl^-, NO3^-） and a Schiff base ligand 2-[（4-methylphenylimino）methyl]-6-methoxyphenol （C15HIsNO2, L） which was obtained by the condensation of o-vanillin （2-hydroxy-3-methoxybenzaldehyde） with p-toluidine. Both 1 and 2 were characterized by single-crystal X-ray diffraction technique, elemental analysis, molar conductance, FT-IR, UV-Vis, IH-NMR spectra and thermogravimetrie analysis. The Schiff base ligand and its zinc（Ⅱ） complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia Coli, Staphylococcus aureus and Bacillus Subtilis. The results show that these complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.