Coordination and Photoisomerization of Azobenzene-Amino Acid Schiff Base Copper(II) Complexes to Lysozyme

In this study, we exhibited an amino acid (arginine and threonine) derivative Schiff base copper(II) complexes incorporating an azobenzene moiety as a photoresponsive site and conjugated it to egg white lysozyme, a well-known protein, to change ligand conformation under binding to lysozyme. Among several spectroscopic investigations, ESR clearly showed that the nitrogen atom of the amino acid residue of lysozyme was bound to the paramagnetic copper(II) ion of the complex, and UV light irradiation confirmed photoisomerization of the azobenzene moiety of the ligand to cis-form. The binding mode was considered by means of spectroscopic as well as computational methods, whereas complete crystallographic verification was still a preliminary stage.

Substituent effect on spectral and antimicrobial activity of Schiff bases derived from aminobenzoic acids

The dependence of electronic absorption spectra antimicrobial property on the substituent position was investigated using three Schiff bases derived from salicylaldehyde and isomeric aminobenzoic acids in three solvents of different polarities. The absorption maxima in all three solvents exhibited dependence on the position of substituent with the absorption maxima undergoing a red shift as solvent polarity increased. The in vitro antibacterial activity of the compounds against some clinically important bacteria namely Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), Enterococcus feacalis (ATCC 29212) was determined in N,N”-dimethylformamide and 1,4-dioxane using the agar dilution method. The results revealed that the ortho and meta substituted Schiff bases exhibited better antimicrobial activity in the non-polar solvent.

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) Å, 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.

Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes

Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin （BSA）, which afforded BSA binding Schiff-base metal complexes （BSA-SalGluM, M=Cu, Co, Ni, Zn）. The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.

Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

Six new complexes of lanthanum with amino acid Schiff base ligands, A-F, were prepared in methanol-aqueous solution. The composition and properties of the title complexes were characterized by elemental analysis, molar conductance, infrared, electronic spectra, H-1 NMR, thermogravimetric and differential thermal analysis.

Syntheses and Characterizations of Cu Ln Heterobinuclear Complexes with Schiff Base from 3-Formylsalicylic Acid and Ethylene Diamine

Seven heterobinuclear complexes of Cu-Ln with N, N'-bis(3-carboxylsali cylidene) ethylenediamine(ES) were synthesized and characterized by elemental analysis, molar conductivity, thermogravimetry, IR and electronic spectra. The room temperature magnetic moments show that there are basically no spin exchange interactions between the ions of Cu2+ and Ln(3+) in the CuLnESCl . nH(2)O compounds.

SYNTHESIS AND CHARACTERIZATION OF AMINO－ACID SCHIFF BASE AND ITS GERMANIUM COMPLEX

Condensation of eqqimolar quantities of salicylaldehyde and a-amino acid (glycine, alanine, valine, leucine, Phenylalanine, serine, cysteine) in absolute Methanol-KOH gives the amino acid Schiff base[1]. Its germanium tetrachloride adducts of the type GeCL. (sal=aa.k)2 have been prepared in absolute mothanol[2]and characterized by elemental analyses, conductance measurements, IR and 1H-NMR spectra, electronic spectra, cyclic voltammetry and thermal analyses. etc.

Synthesis,Crystal Structure and Thermoanalysis of Complex of Zn(II) with Aminomethanesulfonic Acid-5-bromosalicylaldelyde Schiff Base

The title complex [Zn（L）（phen）（CH3OH）] （L = C8H6BrO4NS, aminomethanesulfonic acid 5-bromo-salicylaldelyde schiff base; phen = 1,10-phenanthroline） has been synthesized and characterized by X-ray diffraction method. The crystal belongs to monoclinic, space group P21/c with a = 1.8712（3）, b = 1.38008（19）, c = 0.83685（12） nm, β = 97.791 （2）°, Mr = 569.72, V = 2.1411 （5） nm^3, Z= 4, Dc = 1.767 g/cm^3,μ = 3.151 mm^-1, F（000） = 1144, the final R = 0.0402 and wR = 0.0885. The central Zn（Ⅱ） is six-coordinated by one nitrogen and two oxygen atoms from the Schiff base, two nitrogen atoms from 1,10-phenanthroline and one oxygen from methanol to form a distorted octahedral coordination geometry.

Synthesis, oxygenation and catalytic performance of manganese complex with p-aminomethyl benzoic acid Schiff base

The amino acid Schiff base complex (Sal-AMBA-Mn) was prepared with p-amino-methylbenzoic acid, salicylaldehyde and Mn(OAc)2·4H2O. Its structures was characterized with IR and UV spectra. Oxygenation mechanism of the complex in N, N-dimethylformamide solution was investigated. The results show that lower temperature is in favor of the oxygenation, and energy, enthalpy and entropy are -3.8 kJ/mol, -4.2 J/mol and -161.44 J/(mol·K), respectively. In the presence of the manganese complex, dehydroepiandrosterone acetate is effectively oxidized by molecular oxygen and the corresponding enone 7-ketodehydroepiandrosterone acetate is obtained. The yield is 62.1% when the oxidation is carried out under the reaction conditions of 60 ℃, 2 MPa of O2 pressure, C5H5N as a solvent and molar ratio of the substrate to the complex of 1:10.

Synthesis, spectral, 3D molecular modeling and antibacterial studies of dibutyltin (IV) Schiff base complexes derived from substituted isatin and amino acids

New dibutyltin(IV) complexes of Schiff base derived from 5-chloroindoline-2,3-dione, indoline- 2,3-dione with amino acids (tryptophan, alanine and valine) were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, and biological activity. The analytical data showed that the Schiff base ligand acts as bidentate towards metal ions via the azomethine nitrogen and carboxylate oxygen by a stoichiometric reaction of M:L (1:2) to form metal complexes. NMR (1H, 13C and 119Sn) spectral data of the ligands and metal complex agree with proposed structures. The conductivity values between 14 - 27 ohm-1cm2mol-1 in DMF imply the presence of non-electrolyte species. 3D molecular modeling and analysis of bond lengths and bond angles have also been conducted for a representative compound, [Bu2Sn(L2)2], to substantiate the proposed structures. Antibacterial results indicate that the metal complexes are more active than the free ligands.

Synthesis and characterization of new lan-thanide complexes with Schiff base N-(o-vanil-lylidene)-anthranilic acid

ＳｙｎｔｈｅｓｉｓａｎｄｃｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆｎｅｗｌａｎｔｈａｎｉｄｅｃｏｍｐｌｅｘｅｓｗｉｔｈＳｃｈｉｆｂａｓｅＮ（ｏｖａｎｉｌｌｙｌｉｄｅｎｅ）ａｎｔｈｒａｎｉｌｉｃａｃｉｄＨｕＸｉａｏｌｉ１，ＬｉＤｏｎｇｃｈｅｎｇ２，...

5-硝基水杨醛氨基酸Schiff-bases铜配合物与DNA相互作用的研究

用电子光谱、荧光淬灭光谱和循环伏安的方法,研究了(苯丙氨酸缩5-硝基水杨醛)铜(1)和(组氨酸缩5-硝基水杨醛)铜(2)与 DNA 的作用.结果表明,配合物均以插入模式与 DNA 作用;配合物与 DNA 作用强弱为:配合物(2)>配合物(1).

α,β-Dehydroamino Acid Synthesis through Proline-Catalyzed Aldol Condensation with a Glycine Schiff Base

A general protocol for the synthesis ofα,β-dehydroamino acids and their peptides was developed.Proline efficiently catalyzed an aldol condensation reaction of a glycine Schiff base with a variety of aldehydes.The hydroxy group on the benzophenone imine was crucial for high Z/E selectivity and further transimination for protecting group-freeα,β-dehydroamino esters.Peptide elongation of both the C-and N-terminals highlighted the usefulness of our present protocol.

Natural Acid Catalyzed Synthesis of Schiff under Solvent-Free Condition: As a Green Approach

The following article has been retracted due to the investigation of complaints received against it. The Editorial Board found that the paper has been submitted to other journals at the same time. The scientific community takes a very strong view on this matter, and the International Journal of Organic Chemistry treats all unethical behavior seriously. This paper published in Vol. 2 No.2 166-171, 2012, has been removed from this site.

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.

Schiff-base Amino Alcohol-zinc Complex for Enantioselective Addition of Phenylacetylene to Aromatic Ketones

A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.

具有激素活性的Schiff碱化合物的研究（Ⅰ）──苯氧乙酸类Schiff碱的合成及其生物活性

具有激素活性的Ｓｃｈｉｆｆ碱化合物的研究（Ⅰ）──苯氧乙酸类Ｓｃｈｉｆｆ碱的合成及其生物活性汪焱钢，叶文法，尹大学，黄君珉，陆爱红（华中师范大学化学系，武汉，４３００７０）关键词Ｓｃｈｉｆｆ碱，氨基苯氧乙酸，植物激素活性芳胺的Ｓｃｈｉｆｆ碱类化合物，...

非均相Schiff碱铬(III)配合物催化环己烯环氧化性能的研究

将3种典型的氨基酸-水杨醛Schiff碱铬(III)配合物固载于介孔MCM-41上,制得非均相Schiff碱铬配合物,用傅里叶变换红外光谱、紫外-可见光谱、X射线固体粉末衍射、N2吸附和元素分析对其结构进行了表征,并以30%H2O2为氧化剂,考察该配合物对环己烯环氧化反应的催化性能.结果表明,均相配合物非均相化后,其催化活性明显提高.在较优的反应条件下,环己烯转化率可达52.6%,环氧环己烷选择性为73.5%,且该非均相催化剂重复使用6次后,仍保持较高的催化活性.

水杨醛缩5-氨基水杨酸Schiff碱及其稀土配合物合成、表征和抑菌活性

以水杨醛和5-氨基水杨酸为原料合成了水杨醛缩5-氨基水杨酸,并以其为配体合成了3种新的 Schiff碱稀土配合物(分别为轻Nd、中Gd和重Yb稀土配合物),通过IR、1H NMR、TG-DTA和摩尔电导等测试技术表征其结构:配体以四齿形式参与配位,配位数分别为7(Nd)和9(Gd和Yb)。抑菌活性测定结果表明,所合成的配体和配合物对金黄色葡萄球菌、大肠杆菌和枯草杆菌均表现出不同程度的抑菌效果,其中对大肠杆菌的抑菌效果最好。从整体看,无论是配体还是配合物,它们的抑菌作用都随着浓度的增大而增强。在较低浓度下,中稀土和重稀土配合物的抑菌作用比氢稀土好;在高浓度条件下,轻稀土配合物的抑菌效果好。

硫酸钆与水杨醛氨基酸Schiff碱配合物的研究

用硫酸钆与水杨醛氨基酸Ｓｃｈｉｆ碱，在水溶液中反应，合成了五种新的配合物，通式为Ｇｄｍ（ＳａｌＡＡ）ｎ（ＳＯ４）ｐ·ｘＨ２Ｏ（式中Ｓａｌ＝水杨醛、ＡＡ＝甘氨酸、Ｌ谷氨酸、Ｌ蛋氨酸、Ｌ胱氨酸和Ｌ赖氨酸，ｍ＝１～４，ｎ＝１～２，ｐ＝０、１、２，ｘ＝３、８、１２）。通过元素分析、摩尔电导、红外光谱、荧光光谱、紫外－可见光谱、差热热重分析对合成配合物的组成、性质进行了研究。