Cobalt Schiff base complexes: Synthesis characterization and catalytic application in Suzuki–Miyaura reaction

3-Methoxysalicylaldehyde was condensed with the amines 4-aminoacetophenone and 2-amino-5-bromopyridine to obtain Schiff base ligands, 1 and 2, which were coordinated to cobalt salts as complex 1 and complex 2, respectively. The synthesized ligands and complexes were characterized by spectroscopic(FT-IR,UV–Vis,~1H-NMR and mass spectrometry), thermal(TGA) and elemental analysis. The structures of the complexes were verified by evaluating their magnetic susceptibility and spectroscopic evidences. Synthesized complexes were studied for their catalytic activity in the Suzuki–Miyaura cross-coupling of aryl halides with phenylboronic acid. Optimized reaction yields 90% of the cyanobiphenyl for complex 1 and 91% for complex 2 with 0.1 mmol of catalyst loading thereby substantiating the C\\C coupling efficiency of the synthesized complexes, 1 and 2.

STUDIES ON THE PROPERTIES OF SCHIFF BASE TYPE ARYLMERCURY COMPOUNDS Ⅲ TRANSMETALLATION REACTION OF SCHIFF BASE TYPE ARYLMERCURY COMPOUNDS WITH METALLIC TIN

The transmetallation reaction of 4 Schiff base type arylmercury compounds with metallic tin has been carried out in refluxing xylene.It was found that the reaction proceeds in the same manner as that of chloro[2-(phenylazo)phenyl]mercury(Ⅱ) to give dichlorobisaryltin(Ⅳ).The ~1H NMR spectra of the products provide evidence for the presence of N→Sn intramolecular coordination.The formation of dichlorobisaryltin(Ⅳ)as a unique product probably arises from the N→Sn intramolecular coordination which results in the increasing of the stability of the molecule.

Poly (N-Isopropyl Acrylamide-<i>Co</i>-Vanillin Acrylate) Dual Responsive Functional Copolymers for Grafting Biomolecules by Schiff’s Base Click Reaction

This article reports on the synthesis of acrylate monomer from renewable material. Vanillin was selected to be the start material to produce new monomer called vanillin acrylate and abbreviated by (VA). It has been successfully investigated by 1H, 13C NMR, IR and UV and all results were in logic state. The next step was to synthetize three different thermo-responsive functional copolymers by incorporation of three different molar ratios of vanillin acrylate (10, 20, 30 mol%) with N-Isopropylacrylamide via free radical polymerization by AIBN as initiator in solution. All copolymers were deduced by 1NMR and IR and all showed the presence of aldehyde group. The copolymer was used for grafting of tryptophan and β-alanine through the chemical link between amino group and the active aldehyde group by click reactions to form Schiff’s base imine compounds. Moreover, polymers were also elucidated by 1HNMR, IR and UV, Size Exclusion Chromatography (SEC) was used for the molecular weight determination, differential scanning calorimeter (DSC) for glass temperature of solid polymers, XRD for crystallinity. UV-vis Spectroscopy was used for the determination of phase separation or the lower critical solution temperature (Tc) of polymers solution not only in deionized water but in pH5 and pH11. The mount of conversation and linked amino acid was determined by UV-vis Spectroscopy.

Symmetrical Palladium (II) N,N,O,O-Schiff Base Complex: Efficient Catalyst for Heck and Suzuki Reactions

Palladium is arguably the most versatile and most widely applied catalytic metal in the field of fine chemicals due to its high selectivity and activity. Palladium catalyst offers an abundance of possibilities of carbon-carbon bond formation in organic synthesis. In this research, three different Schiff base ligands have been prepared by condensation reaction between appropriate aldehyde or ketone with amine namely 2,2-dimethyl-1,3-propanediamine in the molar ratio of 2:1. The corresponding palladium (II) Schiff base complexes were prepared through the reaction between the Schiff base ligand with palladium (II) acetate in a molar ratio 1:1. FTIR, 1H-NMR and 13C-NMR spectroscopic data revealed that the ligands are N,N,O,O-tetradentate coordinated to the Pd atom through both the azomethine N atoms and phenolic O atoms. From X-ray Crystallographic analysis, it showed that the complex exists as square planar geometry. The synthesized palladium (II) Schiff base complexes were then subjected in catalytic Heck and Suzuki reaction of iodobenzene.

手性Schiff Base-Ti(OR)_4配合物催化醛的不对称硅腈化反应

设计合成了新型手性Ｓａｌｅｎ－Ｔｉ（ＯＲ）４配合物催化剂，用其催化一系列醛的不对称硅腈化反应，得到了ｅ．ｅ．值为２２．４％～８７．１％的氰醇．催化剂中抗衡离子的Ｌｅｗｉｓ碱强烈地影响催化活性，但对反应的对映选择性影响很小，并探讨了其不对称催化反应机理．

手性三齿Schiff-base配体的合成及其催化的不对称Henry反应研究

以L-酪氨酸甲酯盐酸盐为原料,通过格氏反应合成了一种手性β-氨基醇;以水杨醛为原料,通过溴代反应合成了3,5-二溴水杨醛和5-溴水杨醛;将手性β-氨基醇和溴代水杨醛在乙醇中缩合,制备了两种手性三齿Schiff-base配体.产物的结构经IR,1 H NMR,13C NMR和MS表征确定.将配体应用于催化不对称Henry反应中,考察其在不同反应条件下的催化性能,在最优化的反应条件下,不同底物均获得了较好的催化效果,产率最高达95%,ee值最高达90%.

Some Novel Schiff Bases from Pyruvic Acid with Amines Containing N &S Donor Atoms: Synthesis, Spectral Studies and X-Ray Crystal Structures

Four Schiff bases, from pyruvic acid (1) with amines containing N and S donor atoms, thiocarbohydrazide (2, 61%), 2-methyl-3-thiosemicarbazide (3, 26%), S-benzyldithiocarbazate (4, 51%) and S-n-octyldithiocarbazate (5, 63%) have been successfully synthesized. The conventional method was used and a series of novel linear and cyclic Schiff bases were obtained with or without catalyst. All the Schiff bases were fully characterized by CHN elemental analysis, FT-IR, 1H & 13C NMR, EI-MS and two of the Schiff bases were further characterized by X-ray crystallographic structure analysis. Compound 2 crystallizes in the triclinic space group P-1 and unit cell dimensions are: a = 4.1777(8), b = 5.9538(11), c = 13.458(3) &ARING;, α = 92.759(6), β = 90.813(6), γ = 100.040(6)°, R1 = 0.0439. Compound 3 crystallizes in the orthorhombic space group P n a 2(1) and unit cell dimensions are: a = 5.5992(2), b = 11.3962(5), c = 10.6473(5), α = 92.759(6), β = 90.813(6), γ = 100.040(6)°, R1 = 0.0285. Compounds 2 and 3 were obtained as cyclic Schiff bases which are triazine derivatives.

Synthesis and mesomorphic properties of fluorinated Schiff's base liquid crystals containing vinyl end groups

Three kinds of fluorinated Schiff＇s base esters, 4-allyloxy-2-X-6-X-benzoic acid 4-[（2, 3, 4-trifluorophenylimino）methyl]phenyl ester, where X=H or F, were synthesized and characterized. Their chemical structures were identified by Fourier transform infrared spectroscopy （FTIR） and ^1H nuclear magnetic resonance （^1H NMR）. Their mesomorphic properties were studied by polarized optical microscopy （POM） and differential scanning calorimetry （DSC）. It was found that all the three compounds exhibited enantiotropic nematic phases only. And their cleating point temperature and thermal range of mesophase decreased with the number of fluorine atoms on the rigid core of the compounds; while their melting point temperature showed no distinct regularity.

The Rapid Synthesis of Schiff-Base without Solvent under Microwave Irradiation

A microwave-assisted preparation of a series of Schiff-base via efficient condensation of salicylaldehyde and aryl amines without solvent is described in high yield as well as environmental friendship reaction in organic synthesis.

Studies on A Series Complexes of Copper(Ⅱ),Zinc(Ⅱ),Cobalt(Ⅲ) with Schiff Base Derived from d-Glucosamine and Salicylaldehyde

Copper(Ⅱ), zinc(Ⅱ), cobalt(Ⅲ) complexes with the Schiff base derived from salicylaldehyde and d glucosamine were synthesized. These compounds abbreviated as SG, CuSG, ZnSG, CoSG were characterized by elemental analyses, IR, UV Vis, 1 H NMR and MS spectrum. ESR spectrum, magnetic susceptibility measured by Evans method for CuSG had also been done. It is suggested that the complexes in solution have pseudotetrahedral structure. It was found that SG would occur a photochemical reaction if a beach of 355 nm ultravisible light shone on its aqueous solution. The reaction was in further research.

Syntheses of Ferrocenyl Schiff Bases Using Molecular Sieves and AlCl_3 as Catalysts

In order to study the donor ability of ferrocenylimines as directing ortho metalation group（DMG） to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new methods using molecular sieves（0.4nm） and AlCl3 as catalysts. The reaction periods were reduced using these two catalysts in contrast with Al2O3, which was a traditional method used in the literature. In addition, as an important feature of these schiff bases, we found that they were unstable as oils in air or when filtrated through silica gel, but were stable as solids. The structures of the new compounds were confirmed by IR, ^1H NMR and HRMS.

Characterizing some gossypol and gossypolone Schiff's bases by studying their fragmentation patterns with electrospray ionization tandem mass spectra

To investigate the structural form of gossypol and gossypolone Schiff＇s bases, seven relevant Schiff＇s bases were synthesized and the electrospray ionization-tandem mass spectrometry （ESI-MS/MS） with low-energy collision-induced dissociation was used to analyze their fragmentations. A common fragmentation pathway with the loss of RNH2 from those schiff＇s bases quasi-molecular ions was observed and proposed on the basis of their MS/MS spectra data. This common pathway indicated that those Schiff＇s bases existed mainly as the enamine form not the imine form previously showed in most reports.

Antifungal Evaluation of Copper(Ⅱ) Complex from a Schiff Base Derivative of Pyrazine on Schizosaccharomyces pombe

A new copper(Ⅱ) complex of CuLCl_2, where L = N^1-(1-pyrazin-2-yl-ethylidene)-ethane-1,2-diamine, a tridentate Schiff base derived from 2-acetylpyrazine has been prepared. The complex has been characterized by FT-IR, elemental analysis and single-crystal X-ray diffraction studies. Structural studies reveal that CuLCl_2 is a mononuclear copper(Ⅱ) complex with distorted square pyramidal geometry. Antifungal activity of CuLCl_2 was investigated by use of microcalorimetric measurement system and evaluated against S. pombe. It has high antifungal activity with IC_(50) = 213 μg/mL.

New Schiff Bases from 6,6’-Diformyl-2,2’-Bipyridyl with Amines Containing O, S, N and F: Synthesis and Characterization

Eight novel Schiff Bases, from 6,6′-diformyl-2,2′-bipyridyl (1a, 43%)with O, N, S and F containing amines: Thiosemicarbazide (2a, 70%), 4-Ethyl-3-thiosemicabazide (2b, 75%), 4,4-Dimethyl-3-thio-semicarbazide (2c, 75%), S-benzyldithiocarbazide, SBDTC (2d, 80%), (Trifluromethyl) phenylhy-drazine (2e, 80%), 4-Phenyl-3-thiosemcarbazide (2f, 80%), Thiocarbazide (2g, 70%), 2-Amino-thiophenol (2h, 65%), have been synthesized. The conventional method of synthesis of the Schiff bases involves refluxing the reaction mixture containing the diformyls and amines for 1 hour. The solid products that had formed were filtered off using suction filtration. In few reactions, 2 - 3 drops of conc. sulfuric acid were used to obtain high yield. The structures of all eight novel synthesized compounds have fully been characterized by spectroscopic (IR, NMR, MS) methods.

Synthesis and Characterization of 2,2’-Bipyridyl-5,5’-Dialdehyde Schiff Bases from O,S,N and F-Containing Amines

Design and synthesis of organic chelating agents containing nitrogen and sulfur as donor atoms and their metal complexes is an interesting field of research for their different types of activities. The bi-dentate N,N chelating agent such as 2,2-Bipyridal has been playing a vital role in synthetic and medicinal chemistry. 2,2-Bipyridal has been used to prepare many mixed-ligand complexes. Different ligand complexes prepared from 2,2-Bipyridyl are used in different areas such as molecular catalysis, solar energy conversion, calorimetric analysis, herbicides, molecular recognition, self-assembly, antineoplastic agents, and nucleic acid probes. Another important property of these types of compounds is the triplet state photosensitizing character of bipyridyl nucleus, which is shown in metal complexes. It is also found that compounds containing O,S,N atoms have received considerable attention because of their pharmacological studies like anticancer, antibacterial, and antitumour activities. Therefore, it has been decided to synthesize Schiff bases derived from 2,2’- bipyridyl-5,5’-dicarbaldehyde compounds with O,S,N and F-containing amines and study their antibacterial properties. Several new Schiff bases have been synthesized and fully characterized by spectral data. This paper presents the synthesis and characterization of newly designed Schiff bases.

Self-assembled three-dimensional carbon networks with accessorial Lewis base sites and variational electron characteristics as efficient oxygen reduction reaction catalysts for alkaline metal-air batteries

Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In this study,we develop a novel solvent method to prepare interconnected N,S co-doped three-dimensional（3D）carbon networks with tunable nanopores derived from an asso-ciated complex based on melamine and sodium dodecylbenzene sulfonate（SDBS）.After the intro-duction of silica templates and calcination,the catalyst exhibits 3D networks with interconnected 50-nm pores and partial graphitization.With the increase of the number of Lewis base sites caused by the N doping and change of the carbon charge and spin densities caused by the S doping,the designed N,S co-doped catalyst exhibits a similar electrochemical activity to that of the commercial 20-wt%Pt/C as an oxygen reduction reaction catalyst.In addition,in an aluminum-air battery,the proposed catalyst even outperforms the commercial 5-wt%Pt/C catalyst.Both interconnected porous structures and synergistic effects of N and S contribute to the superior catalytic perfor-mance.This study paves the way for the synthesis of various other N-doped and co-doped carbon materials as efficient catalysts in electrochemical energy applications.

Syntheses and Crystal Structures of Calix[4]arene Dithiocarbazate Schiff Bases

The regioselective syntheses of novel p-tert-butylcalix[4]arenes with functional aldehyde and dithiocarbazate Schiff base groups were carried out. p-tert-Butylcalix[4]arene was alkylated with o-, p-（ω-chloroalkoxy）- benzaldehydes in the system of K2CO3/KI/CH3CN to give calixarene 1,3-dialdehydes. Then the condensation reactions of active calixarene aldehydes with S-methyl and S-benzyldithiocarbazate, calixarene sulfur-containing Schiff bases were efficiently obtained in satisfied yields. The single crystal analysis of the four representative products shows that calixarene aldehydes and Schiff bases exist in cone conformation and there are interesting intermolecular hydrogen-bands and π...π interaction in the crystals.

基于密度泛函理论的S掺杂碳载体负载Pt催化剂对氧还原反应的影响

采用密度泛函方法对比研究了Pt/C催化剂中碳载体掺S前后对氧还原反应(ORR)的影响。从电荷分布、态密度及d带中心等性质出发,分析了金属-载体间相互作用,研究了ORR各物种在催化剂上的吸附并计算了ORR过电势。结果表明:S掺杂使得碳载体表面发生了电子转移,S上的电子转移到邻近的C原子上,负载Pt纳米颗粒后,Pt金属上的电子转移给了碳载体;Pt在S掺杂碳载体上的吸附更强,形成了Pt—C键和Pt—S键,Pt纳米颗粒的分散度和稳定性得到了提升;掺S使得催化剂d带中心下降,对ORR各中间体的吸附减弱,ORR过电势降低,表明掺S能提高催化剂的催化活性。

Synthesis of 5-Substituted 2, 9-Dimethyl-1,10-Phenanthroline Dialdehydes and Their Schiff Bases with Sulfur-Containing Amines

Eight new Schiff bases of 5-nitro and 5-bromo-substituted 1,10-phenanthroline-2,9-dicarboxaldehydes with sulfur-containing amines, thiosemicarbazide, S-alkyl/aryl dithiocarbazates and 2-mercaptoaniline have been synthesized and characterized by a variety of spectroscopic methods. The condensation reactions of the dialdehydes with the amines were carried out both in the presence and absence of conc. sulfuric acid. A significant increase in yield of the Schiff bases was observed when the reactions were carried out in the presence of sulfuric acid.

Antibacterial Activities of New Schiff Bases and Intermediate Silyl Compounds Synthesized from 5-Substituted-1,10-phenanthroline- 2,9-dialdehyde

Schiff bases are known to possess anticancer, antibacterial, antifungal, antitubercular, anti-inflammatory, antimicrobial and antimalarial properties. In this paper antibacterial studies against variety of plants and human pathogenic bacteria with eight newly synthesized Schiff bases and several intermediate silyl compounds have been reported. The antibacterial activities of the synthesized compounds were primarily determined by paper disc diffusion method. The minimum inhibitory concentration (MIC) of each compound was also determined by tube dilution process. Seven different human pathogenic bacteria and eighteen different plant pathogenic bacteria were used for the antibacterial activity studies. While all synthesized compounds have shown significant antibacterial activity, one intermediate silyl compound has shown remarkably high antibacterial property. 5-substituted derivatives have shown relatively higher activity than non-substituted compounds. Polar substituent which increases hydrophilicity may have a positive impact on the antibacterial property.