Schiff Base Research Papers - Academia.edu (original) (raw)

Numerous studies have suggested relationships between myeloperoxidase, inflammation, and atherosclerosis. MPO-derived reactive chlorinating species (RCS) attack membrane plasmalogens releasing ␣-chloro-fatty aldehydes (␣-Cl-FALDs) including 2-chlorohexadecanal (2-ClHDA). The molecular targets of ␣-Cl-FALDs are not known. The current study demonstrates 2-ClHDA adducts with ethanolamine glycerophospholipids and Fmoc-lysine. Utilizing electrospray ionization mass spectrometry, chlorinated adducts were observed that are apparent Schiff base adducts. Reduction of these Schiff base adducts with sodium cyanoborohydride resulted in a novel, stable adduct produced by the elimination of HCl. NMR further confirmed this structure. 2-ClHDA adducts with ethanolamine glycerophospholipids were also substrates for phospholipase D (PLD). The hydrolysis products were derivatized to pentafluorobenzoyl esters, and further structurally confirmed by GC-MS. Multiple molecular species of 2-ClHDA-N-modified ethanolamine glycerophospholipids were observed in endothelial cells treated with 2-ClHDA. These results show novel Schiff base adducts of ␣-Cl-FALDs with primary amines, which may represent an important fate of ␣-Cl-FALDs.

- by
- •
- Physical Chemistry, Peroxidase, Endothelial Cells, Amines

batches were pooled, dried in vacuo, and stored in the dark at 4 OC. Optical and NMR spectra and rechromatography by HPLC indicated that the final product was stable when so stored. At the present time, accurate extinction coefficients for the metal-free methyl ester have not been obtained and the quantity of the ester can be estimated only from the intensity of NMR spectra. On the basis of this, the overall yield from the heme content of the terminal oxidase was estimated to be on the order of 1620%. Major losses occurred in the initial acid-acetone extract and during the demetallization procedure. Abstract: Covalent modification by two-step labeling is illustrated by a blocker-fixer sequence, in which a protein forms a reversible complex with a blocker, which is then converted to an irreversible adduct by the fixer. When the Schiff base-forming enzyme, acetoacetate, decarboxylase (AAD), is used as an in vitro model, the blocker-fixer sequence is exemplified by ethyl acetoacetate (EAA) as the blocker and borohydride as the fixer. When reaction or removal of unbound blocker competes with protein labeling (e.g., with NaBH, as fixer), the quantitative expression for the extent of labeling is @J = 1 -(1 + p)", where p is the ratio of the initial blocker concentration, So, to the dissociation constant for the reversible protein-blocker complex.

- by Thomas Morton and +1
- •
- CHEMICAL SCIENCES, Schiff Base

Quadridentate Schiff base ligands derived from 1,2-diamines and fluorous derivatives of salicylaldehyde were prepared and the corresponding manganese(III) complexes were tested as catalysts in the selective oxidation of alkyl aryl sulfides with PhIO. Complexes bearing two fluorinated ponytails were soluble in standard organic solvents and were used under classical homogeneous conditions, whereas heavily fluorinated complexes could be used in a CH 3 CN/perfluorooctane biphasic system. In both cases, sulfoxides were obtained as the main products, together with variable amounts of sulfones (≤10%), depending on the nature of the substrate and the catalyst. When reactions were carried out under fluorous biphasic (FB) conditions, the selectivity for sulfoxides was improved and the catalyst could be easily recovered by simple phase separation and reused up to four times. Despite their good chemoselectivity, catalytic efficiency and recyclability, chiral fluorous (salen)manganese(III) complexes showed low enantioselectivities in preliminary experiments run under fluorous biphasic conditions.

- by Marco Cavazzini
- •
- Chemical Engineering, Phase Separation, Schiff Base

Chronic renal failure is often associated with a resistance to the biologically active form of vitamin D 3 , the nuclear hormone 1␣,25-dihydroxyvitamin D 3 (VD). The actions of VD are mediated by the vitamin D receptor (VDR), a ligand-dependent transcription factor that binds as a dimeric complex with the retinoid X receptor (RXR) to specific DNA binding sites in the promoter regions of primary VD responding genes, referred to as VD response elements (VDREs). It could be shown in this study that uremic solutions derived from ultrafiltrate from hemodialysis patients and dialysate from peritoneal dialysis patients had an inhibitory effect on the complex formation and ligand inducibility of VDR-RXR heterodimers on different VDRE types. This inhibition was attributed to the formation of Schiff bases between ''reactive aldehydes'' and lysine residues of the DNA binding domain (DBD) of the VDR, but point mutagenesis data of different lysine residues in this study could not confirm this idea. However, the inhibitory effect of uremic solutions could also be observed for the complex formation of other homo-or heterodimer forming nuclear receptors, whereas an as a monomer binding nuclear receptor did not appear to be affected. These results indicate that VDR is a target of substances in uremic solutions in vitro, but also to some extent other nuclear receptors (i.e., other endocrine signaling systems) may be affected by renal failure.

- by Carsten Carlberg
- •
- Transcription Factors, Nuclear Receptor, Protein-DNA interaction, Mutagenesis

New Schiff base chelates of Cu(II), Co(II), Ni(II) and Zn(II) derived from benzil-2,4-dinitrophenylhydrazone with aniline have been synthesised. Microanalytical data, molar conductance, and magnetic susceptibility values have been obtained, and IR, 1 H NMR, 13 C NMR, UV-Vis, CV and EPR spectral studies have been carried out to suggest tentative structures for the complexes.

- by Alexander Steiner
- •
- Chemical, Copper, Magnetic Susceptibility, Zinc

adduct specific for DEB, PYRV, requires-due to its tertiary amine structure-other techniques. The reaction products were identified by GC/MS, PYRV by 13C and 'H NMR, and THBV because of its formation by reduction of the Schiff bases of... more

The medium and far IR spectra of the title compounds are discussed and related to the molecular structure. The spectral analysis is supported by a normal coordinate treatment based on a simplified molecular model. Bands near 375 and 290 cm−1 are assigned to the Co-O and Co-N stretching vibrations, respectively; the corresponding force constants are estimated to be 1.11 and

- by Victor Poblete Pulgar
- •
- Chemistry, Analytical Chemistry, Molecular modeling, Spectral analysis

We reported recently that Schiff base 1 (Figure 1) is a remarkably general catalyst for the hydrocyanation of aldimines [1] and ketoimines, [2] producing Strecker adducts in >90% ee for most substrates examined (Equation 1). [3] This catalyst was identified and optimized from a parallel library of Schiff base derivatives that was synthesized and screened on solid phase. [1,4]

- by Julius Su
- •
- Chemical Engineering, Inorganic Chemistry, Organic Chemistry, Asymmetric catalysis

Abstract: 2-Ethoxy-6-[(E)-[(2-hydroxyphenyl)imino]methyl]phenol derivative Schiff bases (4-chloro-2-((3-ethoxy-2-hydroxybenzylidene)amino)phenol; 5S1 and 2-((3-ethoxy-2-hydroxybenzylidene)amino)-4-methylphenol; 5S2 have been synthesized and characterized with 1H-NMR, 13C-NMR, IR and elemental analysis in this study. The stable conformers and possible tautomer forms of Schiff base derivatives have been determined in theoretical calculations. All the calculations considering for the energetically stable conformers were performed with Gaussian09 program by using B3LYP/6-311g(2d,p) level of theory. The Gibbs Free energies, stable tautomer forms, H-bond, Mulliken charges, dipole moments, solvent accessibility surface areas (SAS), molecular electrostatic potential values, HOMO, LUMO and band gap energies (EGAP) were also calculated. The consistency between the theoretical and experimental 1H-NMR, 13C-NMR and IR spectra has also been investigated.

- by Ülkü Dilek Uysal
- •
- SAS, DFT, MEP, Schiff Base

The heme pathway enzyme d-aminolevulinate dehydratase is a good marker for oxidative stress and metal intoxication. This sulfhydryl enzyme is inhibited in such oxidative pathologies as lead, mercury and aluminum intoxication, exposure to selenium organic species and diabetes. Oxidative stress is a complicating factor in diabetes, inducing non-enzymatic glucose-mediated reactions that change protein structures and impair enzyme functions. We have studied the effects of high glucose, fructose and ribose concentrations on d-ALA-D activity in vitro. These reducing sugars inhibited d-ALA-D with efficacies in the order fructose Z ribose O glucose. The possible mechanism of glucose inhibition was investigated using lysine, DTT, and t-butylamine. Oxidation of the enzyme's critical sulfhydryl groups was not involved because DTT had no effect. We concluded that high concentrations of reducing sugars or their autoxidation products inhibit d-ALA-D by a mechanism not related to thiol oxidation. Also, we are not able to demonstrate that the formation of a Schiff base with the critical lysine residue of the enzyme is involved in the inhibition of d-ALA-D by hexoses. Ó

- by Vanderlei Folmer
- •
- Cell Biology, Protein structure, Enzyme, Schiff Base

Copper(II) chelates of the Schiff bases (H2L), obtained by condensation of 4-butyryl-3-methyl-1-phenyl-pyrazoline-5-one (HBMPP) with o-phenylene diamine (H2L1) and p-phenylene diamine (H2L2), have been prepared and characterized by elemental analyses, thermogravimetric analyses, magnetic measurements, diffuse reflectance spectra, IR and mass spectra, and conductance measurements. The extractability of copper(II) with H2L in chloroform was examined. Effective extraction was observed with 1 × 10−3 mol dm−3 of ligands at pH 6.5 using H2L1 and pH 7.0 using H2L2. The nature of the extracted species was ascertained by the slope analysis method. The ligand can effectively be used in solvent extraction of copper(II) from aqueous phase to organic phase.

- by Hitesh Barad
- •
- Chemistry, Inorganic Chemistry, Coordination Chemistry, Solvent Extraction
- by Abel Haidoux
- •
- Inorganic Chemistry, Chemical, Crystal structure, Copper

Oxygen absorption–desorption processes for square planar Mn(II), Co(II) and Mn(II) complexes of tetradentate Schiff base ligands in DMF and chloroform solvents were investigated. The tetradentate Schiff base ligands were obtained by condensation reaction of ethylenediamine with salcyldehyde, o-hydroxyacetophenone or acetylacetone in the molar ratio 1:2. The square planar complexes were prepared by the reaction of the Schiff base ligands with Mn(II) acetate, Co(II) nitrate and Ni(II) nitrate in dry ethanol under nitrogen atmosphere. The sorption processes were undertaken in the presence and absence of (pyridine) axial-base in 1:1M ratio of (pyridine:metal(II) complexes). Complexes in DMF indicate significant oxygen affinity than in chloroform solvent. Cobalt(II) complexes showed significant sorption processes compared to Mn(II) and Ni(II) complexes. The presence of pyridine axial base clearly increases oxygen affinity.

- by maaz ali
- •
- Chemistry, Nitrogen, Nickel, Schiff Base

Ten new azo Schiff bases 5a-h and 7a-b were prepared in excellent yields via the condensation of different aromatic amines and a new azoaldehyde, 2-hydroxy-3methoxy-5-(4-methoxyphenylazo)benzaldehyde (4) by two different methods. All new compounds were tested against five microorganisms: Staphylococcus aureus (Gram positive and methicillin resistant), Bacillus subtilis (Gram positive), Kelebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli (all Gram negative). Compounds 4, 5a, 5c, 5d and 5g were moderately active against Staphylococcus aureus and Bacillus subtilis. Compound 7b was highly active against Bacillus subtilis and moderately active against Staphylococcus aureus. Other compounds were inactive against these strains of bacteria. The antifungal activities of these compounds were also tested against eight different fungal species. None of them were active against the fungi species tested.

To investigate the relationship between antimicrobial activities and the formation constants of CuII, NiII and CoII complexes with three Schiff bases, which were obtained by the condensation of 2-pyridinecarboxyaldehyde with DL-alanine, DL-valine and DL-phenylalanine, have been synthesized. Schiff bases and the complexes have been characterized on the basis of elemental analyses, magnetic moments (at ca. 25 °C), molar conductivity, thermal analyses and spectral (i.r., u.v., n.m.r.) studies. The i.r. spectra show that the ligands act in a monovalent bidentate fashion, depending on the metal salt used and the reaction pH = 9, 8 and 7 medium, for CuII, NiII and CoII, respectively. Square-planar, tetrahedral and octahedral structures are proposed for CuII, NiII and CoII, respectively. The protonation constants of the Schiff bases and stability constants of their ML-type complexes have been calculated potentiometrically in aqueous solution at 25 ± 0.1 °C and at 0.1 M KCl ionic strength. Antimicrobial activities of the Schiff bases and the complexes were evaluated for three bacteria (Bacillus subtillis, Staphylococcus aureus, and Escherichia coli) and a yeast (Candida albicans). The structure–activity correlation in Schiff bases and their metal(II) complexes are discussed, based on the effect of their stability contants.

- by sari man
- •
- Inorganic Chemistry, Escherichia coli, Antimicrobial activity, Staphylococcus aureus

A new polymer supported Cu(II) Schiff base complex was synthesized. The solid complex was characterized by Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). Its homogeneous analogue was also prepared. The catalytic performances of the copper complex in oxidation reactions were evaluated for both homogeneous and heterogeneous systems. The copper(II) complex was found to be efficient catalyst for the oxidation of alkenes, alkanes and aromatic alcohols in the presence of hydrogen peroxide as oxidant at room temperature. The catalytic investigation revealed that the solid complex performs better than the homogeneous one as an oxidation catalyst. The solids containing the immobilized complex can be recovered from the reaction medium and reused almost five times, maintaining good catalytic activity. Furthermore, the in vitro toxicity of the ligand and complex was tested against the growth of bacterial species, viz., Staphylococcus aureus and Escherichia coli.

- by Anupam Singha Roy
- •
- Chemical Engineering, Molecular, Old Copper Complex, Copper

The atomic structure of the light-driven ion pump bacteriorhodopsin and the surrounding lipid matrix was determined by X-ray diffraction of crystals grown in cubic lipid phase. In the extracellular region, an extensive three-dimensional hydrogen-bonded network of protein residues and seven water molecules leads from the buried retinal Schiff base and the proton acceptor Asp85 to the membrane surface. Near Lys216 where the retinal binds, transmembrane helix G contains a p-bulge that causes a non-proline? kink. The bulge is stabilized by hydrogen-bonding of the main-chain carbonyl groups of Ala215 and Lys216 with two buried water molecules located between the Schiff base and the proton donor Asp96 in the cytoplasmic region. The results indicate extensive involvement of bound water molecules in both the structure and the function of this seven-helical membrane protein. A bilayer of 18 tightly bound lipid chains forms an annulus around the protein in the crystal. Contacts between the trimers in the membrane plane are mediated almost exclusively by lipids.

- by Janos Lanyi
- •
- Molecular Biology, Hydrogen Bond, X ray diffraction, Schiff Base

A series of new and novel Schiff base derivatives were synthesized and investigated as potential new inhibitors of Jack bean urease. The most potent compounds were 3f with (K i ¼ 0.09 mM) and 3k (K i ¼ 0.122 mM). A pure competitive mechanism of inhibition was observed. Molecular docking studies were also performed to illustrate the binding mode of the compounds. Docking studies were performed on both enzymes from Jack bean urease and H. pylori urease. It was observed that both share the same binding mode. The binding sites of the two urease structures also aligned very well indicating the similarity in binding sites of the enzymes.

- by Dr.Aamer Saeed
- •
- Organic Chemistry, Kinetics, Enzyme Inhibitors, Molecular docking

The synthesis and characterization is reported of four new iron(III) complexes, [Fe(L1)](ClO4) (1), [Fe(L1)](BF4) (2), [Fe(L2)](ClO4) (3), [Fe(L2)](BF4) (4) with the N4O2-donor hexadentate Schiff-base ligands (L1=N,N′,N″,N‴-1,5,8,12-tetraazadodecane-bis(salicylaldiminato), L2=N,N′,N″,N‴-1,5,8,12-tetraazadodecane-bis(3-methoxysalicylaldiminato)) obtained from salicylaldehyde, or a 3-methoxysalicylaldehyde. The iron(III) complexes have been prepared with different counter ions, i.e., ClO4- and BF4-, and characterized by different experimental techniques: X-ray crystallography, IR, ligand field spectroscopy, EPR,

- by Ilpo Mutikainen
- •
- Inorganic Chemistry, Cyclic Voltammetry, Crystal structure, Magnetic Properties

Novel terdentate neutral complexes of Cu II , Ni II , Co II , Mn II , Zn II , Cd II , Hg II , VO II , ZrO II and UO 2 II have been prepared using a Schi base derived from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one (4-aminoantipyrine) and acetoacetanilide. The structural features of the chelates have been con®rmed by microanalytical data, i.r., u.v.±vis., 1 H-n.m.r., e.s.r. and mass spectral techniques. Electronic absorption and i.r. spectra of the complexes indicate an octahedral geometry around the central metal ion, except for the VO II and ZrO II complexes which show square pyramidal geometry. The monomeric and neutral nature of the complexes are con®rmed from their magnetic susceptibility and low conductance values. The cyclic voltammogram of the copper complex in MeCN at 300 K shows a quasi-reversible peak for the couple Cu II /Cu III at Ep c = 0.47 and Ep a = 0.61 V versus Ag/AgCl and two irreversible peaks for Cu II 3 Cu I and Cu I 3 Cu 0 reduction at Ep c = )0.63 and )0.89 V respectively. The e.s.r. spectra of copper and vanadyl complexes in DMSO solution at 300 K and 77 K were recorded and their salient features are reported. The molecular orbital coecients (a 2 , b 2 ) were calculated for complexes. The antimicrobial activity of the ligand and its complexes have been extensively studied on microorganisms such as Staphylococcus aureus, Klebsiela pneumoniae, Bacillus subtillis, Escherichia coli, Citrobacter ferundii and Salmonella typhi. Most of the complexes have higher activities than that of the free ligand.

- by Antonysamy Kulandaisamy
- •
- Inorganic Chemistry, Transition-Metal Oxides, Copper, Escherichia coli

We present a study of the use of chloro-functionalized mesoporous silicas as supports for immobilization of Au(III) Schiff base complex, and use of this composite material as heterogeneous catalyst for homocoupling of aryl boronic acid. The catalyst was characterised by XRD, FTIR, UV-vis DRS, TG-DTA, etc. Catalyst was initially tested using the coupling of phenylboronic acid with bromo benzene in the presence of K 2 CO 3 and with xylene as solvent. The reaction was also tested in the absence of the aryl halide and K 2 CO 3 . The results indicate that in our catalytic system base is not needed for the activation of phenylboronic acid, and its only role is to neutralize the boric acid. The optimized catalysts are also active in the coupling of a range of aryl boronic acids, and after four catalytic runs they show virtually no drop in activity.

- by Swagatika Parida
- •
- Chemical Engineering, Silica, Composite Material, Boric Acid
- by enrique melendez
- •
- Engineering, Chemical Engineering, Chemistry, Analytical Chemistry

The synthesis of N 2 O 3 macrocyclic ligand 8,9,18,19-tetrahydro-7H,17H-dibenzo[f,o][1,5,9,13] dioxadiazacyclohexadecin-18-ol (L 0/2) and preparation of complexes NiLX 2 (X 0/Cl, Br, I, ClO 4 ) and NiLXY (X0/Cl, Br, I and Y 0/ClO 4 ) are reported. NiLX 2 complexes were prepared by facile template reactions of appropriate dialdehyde 2-[3-(2-formylphenoxy)-2-hydroxypropoxy]bezaldehyde (1) and 1,3-diaminopropane in the presence of Ni(II) salts. Reactions of NiL(ClO 4 ) 2 (2d) with lithium halides resulted in NiLXY complexes. From spectroscopic measurements and conductivity studies of the complexes it is followed that the sixcoordinate species NiLX ' are formed in solution except 2d. In all complexes the ligand behaves as a pentadentate ligand. Complexes 2b ×/CH 3 CN and 2b×/1.75CH 3 CN (2b /NiLBr 2 ) contain nickel in a distorted octahedral environment of N 2 O 3 Br donors. #

- by SONIA GIRALDO PEREZ
- •
- Inorganic Chemistry, Macrocycle, Nickel, Template

A new pendant armed Schiff base macrocyclic complex of [CdL] 2+ , was prepared via cyclocondensation of 2,6-bis(2formylphenoxymethyl)pyridine with branched hexaamine in the presence of Cd(II) ion. The ligand was 23-membered... more

- by Hamid Goudarziafshar
- •
- Chemistry, CHEMICAL SCIENCES, Schiff Base

Ru III complexes of the type [RuX(L) 2 (E)] (X ¼ Cl or Br; L ¼ novel bidentate Schiff base ligand; E ¼ PPh 3 or AsPh 3 ) have been prepared by reacting [RuX 3 (E) 3 ] or [RuBr 3 (PPh 3 ) 2 (MeOH)] with two novel bidentate Schiff base ligands derived from 4-(1-methyl-1-mesitylcyclobutane-3-yl)-2-aminothiazole, in a 1:2 molar ratio in benzene, and characterised by analytical, spectral (i.r., electronic, 1 H-, 13 C-n.m.r., and e.p.r.) and electrochemical data. An octahedral structure has been tentatively proposed for all the new complexes. The thermal properties of the ligands and their complexes have been studied by t.g.a. The new Ru III complexes are effective catalysts for the oxidation of alcohols to carbonyl compounds but are unable to oxidise alkenes in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant. The antimicrobial activity of the ligands and complexes have also been tested against six microorganisms.

The synthesis and structural properties of two novel compounds, 4-amino-5-(thien-2-yl ethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one and 4-{[(2-hydroxy-1-naphthyl)methyl-ene]amino}-5-(thien-2-ylmethyl) − 2,4-dihydro-3H-1,2,4-triazol-3-one have been described. 4-Amino-5-(thien-2-ylmethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one was synthesized by treating N-propionyl-2-thien-2-ylethane-hydrazonoate with hydrazine hydrate and the Schiff base was obtained from condensation of substituted amine with 2-hydroxy-1-naphthaldehyde. The Cu(II), Ni(II) and Fe(II) complexes were prepared and characterized by elemental analyses, IR, magnetic moment, UV–Vis, mass spectral data and 1H- and 13C-NMR IR spectra. The Schiff base is coordinated to the metal ions in a tridentate manner with OON donors of the phenolic O, carbonyl O and triazolic N. From the magnetic and UV spectral data, it was found the geometrical structure of Cu(II) and Fe(II) ions are octahedral while Ni(II) ion is square planar.Ab-inito 6-31 G* level calculations provided structural information and IR data that were in good agreement with experimental results.

- by Kerim Serbest
- •
- Inorganic Chemistry, Transition metal chemistry, Schiff Base, Structural Properties

Abstract Schiff base 4-[(2-hydroxy-3-methoxybenzylideneamino)-N-(5-methylisoxazol-3-yl)benzene-sulfonamide has been synthesized from the reaction of 4-amino-N-(5-methylisoxazol-3-yl)benzenesulfonamide(sulfamethoxazole) with 2-hydroxy-3-methoxybenzaldehyde. It has been characterized by elemental analysis, MS, IR, 1H NMR, 13C NMR, HETCOR and UV–Visible techniques. The structure of it also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solid state and the solutions. It crystallizes in the monoclinic space group P21/c with a = 8.2694(7), b = 8.3453(5), c = 26.260(2) Å, β = 97.142(7) °, V = 1798.1(2) Å3, D x = 1.431 g cm−3, R 1 = 0.0529 and wR 2 = 0.1370 [I > 2σ(I)], respectively. Index Abstract The tautomerism in the Schiff base ligands plays an important role for distinguishing their photochromic and thermochromic characteristics. Both phenomena is associated with a proton transfer (enol-imine, O–H···N, keto-amine, O···H–N).

- by Mustafa Yıldız
- •
- Inorganic Chemistry, Coordination Chemistry, Spectroscopy, NMR Spectroscopy

Epilepsy is a disease of complex nature and of different etiology (1). A large number of populations of different age groups and sex are affected by this disease. Mainly, two kinds of epilepsy have been identified, one with grand mal and the other with petit mal. Anticonvulsant drugs with MES (maximal electroshock) activity are generally useful in grand mal, while ScMet (subcutaneous metrazole) antagonists are effective in petit mal. Many drugs have been marketed recently for the treatment of epilepsy (2-4). These include milecemide, zonisamide, lamotrigine, felbamate and tiagabine. Recently, semicarbazones are emerging as novel anticonvulsant drugs. 4-Bromobenzaldeyde semicarbazone and 4-bromophenyl semicarbazones have shown promising activities (5-9). The proposed pharmacophoric requirements in the semicarbazone molecules are:

- by Krishna Nand Singh
- •
- Magnetic Resonance Spectroscopy, Mice, Schiff bases, Schiff Base
- by Tariel Ghochikyan
- •
- Thermodynamics, Chemistry, Organic Chemistry, Pergamon

Acrylamide is a potential cause of a wide spectrum of toxic effects and is classified as probably “carcinogenic in humans”. The discovery of acrylamide in human foods has given rise to extensive studies exploring its formation mechanisms and levels of exposure and has spurred search into suitable analytical procedures for its determination in foodstuffs. However, the exact chemical mechanisms governing

- by alain LEBAIL
- •
- Chemistry, Tandem Mass Spectrometry, Spectrum, Analytical Method

New ferrocene derivatives -1H-1-phenylpyrazole-4-carboxaldehydes containing o-, m-and p-ferrocenylphenyl group at position 3 -were synthesized and characterized. The electrochemical investigation showed that the position of the ferrocenyl group does not affect the redox potential of these compounds. The X-ray crystal structure of the ortho-derivative is also presented. The screening for the in vitro antimicrobial activity against eleven bacterial and three fungal/yeast strains exhibited complete inactivity of these aldehydes, but n-butyl imines of ortho and meta derivatives showed moderate activity compared to those of the used standards.

- by Dragan Ratkovic
- •
- Inorganic Chemistry, Organic Chemistry, Coordination Chemistry, Structure

The copper (II) perchlorate complexes with Schiff base ligands were investigated by X-ray single crystal analysis, electron spectroscopy, infrared and electron paramagnetic spectroscopy. The Schiff bases were obtained as condensation products of 2-pyridinecarboxaldehyde N-oxide with dipropylenetriamine (L 1 ) and triethylenetetramine (L 3 ), respectively.

- by Guido Kickelbick and +1
- •
- Inorganic Chemistry, X Rays, Copper, Electronic Spectra

Schiff bases are aldehyde-or ketone-like compounds in which the carbonyl group is replaced by an imine or azomethine group. They are widely used for industrial purposes and also exhibit a broad range of biological activities. This short review compiles examples of the most promising antimalarial, antibacterial, antifungal, and antiviral Schiff bases. An overview of synthetic methodologies used for the preparation of Schiff bases is also described.

- by Daniel Leite da Silva
- •
- Antimicrobial activity, Schiff Base, Advanced, Biological activity

... Subhra Basak Æ Soma Sen Æ Samiran Mitra Æ C. Marschner Æ WS Sheldrick ... Lorenzotti A (1999) Polyhedron 18:3041 3. Talukder P, Datta A, Mitra S, Rosair G (2004) Z Naturforsch 59b:655 and references therein 4. Mondal N, Mitra S,... more

This paper reports the crystal structure and photoluminescence properties of Ca 9 La 1Àx (VO 4 ) 7 :xEu 31 (x 5 0-1) phosphors synthesized at various temperatures (8501-13501C) in air for 12 h using traditional solid-state reaction method. Rietveld refinement of powder X-ray diffraction pattern of Ca 9 Eu(VO 4 ) 7 indicated that the structure of Ca 9 Eu(VO 4 ) 7 consisted of [VO 4 ] tetrahedra and Ca/Eu atoms were filled in the space between the tetrahedral groups, with a random distribution for Eu 31 ions on four individual Ca crystallographic sites. A major intense sharp emission line, locating at 613 nm under 465 nm excitation, was observed due to the 5 D 0 À 7 F 2 transition of Eu 31 within 4f configurations, which originates from the lower site symmetry in Ca 9 La 1Àx (VO 4 ) 7 :xEu 31 . Interestingly, no concentration quenching was found in this phosphor, and thermal quenching was nearly not affected by Eu 31 concentration. The experimental results suggested that this novel red-emitting phosphor could be applied in white light-emitting diodes.

The interaction of ionizing radiation with the human body, arising either from external sources outside the body or from internal contamination of the body by radioactive substances, leads to biological effects which may later show up as clinical symptoms. In general, these symptoms result from damage to the blood forming organs, digestive system, or central nervous system, depending on the radiation dose. 1-3) Therefore, protecting the body from the toxic effects of radiation has been a major concern in public health. Patt et al. 4) reported that the administration of the sulfurhydryl amino acid cysteine, given to rats before an 8-Gy dose of whole-body Xirradiation, significantly increased the animals' resistance to the cytotoxic effects of the exposure. Since this initial finding, new agents have been developed for cytoprotection. As reviewed 5,6) by Foye, these agents include mercaptans, diand trisulfides, phosphorothioates, acid hydrazides, imidazoles, and amine oxides. Although these compounds are too toxic to be used in the clinic, the need still exists for compounds that are more effective and less toxic for both military and emergency use. Recently, the fact that amifostine (WR2721; NH 2-(CH 2) 3-NH-(CH 2) 2-SPO 3 H 2) has been used to protect 7) cancer patients against the cytotoxicity of ionizing radiation in the clinic has gained much more attention in the search for new cytoprotective agents. Substituted anilines 8) were reported to possess significant radioprotective activity, but some of them are toxic. Blickenstaff et al. 9) reported the Schiff base products of substituted anilines and aryl-aldehyde could reduce the toxicity of substituted anilines but preserve the radioprotective activity. Since the radical scavenging ability of mercaptans and disulfides is wellknown, we speculated that the introduction of these important functional groups into the Schiff base products might provide potent antioxidative and radioprotective activity. In this work, the sulfur-containing Schiff bases of substituted anilines and benzaldehyde have been synthesized and their free radical scavenging, antioxidation, and radioprotection effects were also investigated. Chemistry The synthetic routes to the target compounds (2a-c), (4a, b) and (6a, c) are outlined in Charts 1-3. Initially, the key intermediates, 2-(phenylthio)benzaldehyde (1), 2,2Јdibenzaldehyde sulfide (3), and 2,2Ј-dithiodibenzaldehyde (5) were prepared from thiophenol, 2-mercaptobenzoic acid, and (2-mercapto-phenyl)-methanol, respectively. Thiophenol was reacted with 2-chlorobenzaldehyde in hexamethylphosphoramide (HMPA) in the presence of sodium carbonate at 85°C for 5 h producing the aldehyde 1 in a good yield. Reduction of 2-mercaptobenzoic acid with lithium aluminum hydride gave (2-mercapto-phenyl)-methanol which was used for the subsequent preparation of 3 and 5. Treatment of (2mercapto-phenyl)-methanol with 2-chlorobenzaldehyde in HMPA in the presence of sodium carbonate at 100°C for 5 h

- by LingYih Hsu
- •
- Chemical, Magnetic Resonance Spectroscopy, Antioxidants, Schiff bases
- by Christoph Janiak
- •
- Inorganic Chemistry, Titanium, Transition-Metal Oxides, Copper

Three new nickel(II) dinuclear oxalato-bridged compounds Ni(TAA)(C104)" 0.5ox (1), Ni2(APO-SalE)OX'2H20 (2) and Niphen2oxNiacacE'4H20 (3) have been characterized [TAA = N(CHECH2NH2)3 ox = oxalate, phen = 1,10-phenanthroline, acac = acetylacetonate and APO-sal2 is the Schiff base formed by the condensation of salicylaldehyde and 1,3-diamino-2-propanol]. The crystal structure of 1 has been determined by a single-crystal X-ray analysis. The nickel atom is coordinated by two oxygen atoms of an oxalato ligand and four nitrogen atoms belonging to TAA in an octahedral arrangement. The intermetallic distance of Ni(1)--Ni(2) is 5.412(1) /~. Magnetic measurements (77-300 K) show that three compounds are antiferromagnetically coupled, J = -14.4, -11.25 and -19.3 cm -~ for 1, 2 and 3, respectively.

- by Zdeněk Šindelář and +1
- •
- Inorganic Chemistry, Crystal structure, X Rays, Magnetic Properties

Prussian blue (PB) particles with the size of ca. 5 nm were synthesized and immobilized in a multilayer structure, as a strategy for the potential development of an amperometric transducer for oxidase-enzyme-based biosensors. Multilayer films composed of PB and poly(allylamine hydrochloride) (PAH) were prepared via layer-by-layer (LbL) sequential deposition. The process was carefully monitored by UV-vis spectroscopy and cyclic voltammetry. The increase of the redox current peaks during the layer-by-layer deposition demonstrated that charge propagation within the film occurs. Linear increase of UV-vis absorbance with the number of deposited bilayers indicates that well-organized systems have been elaborated. ITO electrodes coated with PB/PAH films were used successfully for detecting H 2 O 2 , sensitivity being dependent on the number of PB/PAH layers.

- by Susana Torresi and +1
- •
- Materials Engineering, Inorganic Chemistry, Coordination Chemistry, Electrochemistry

In order to understand the effect that diamine ligands induce in the cupric complexes used as catalyst in the oxidative coupling of 2,6-di-tert-butylphenol, a spectrophotometric study of the speciation of copper(II) with 1,3-propanediamine and 1,4-butanediamine both with Cl À or Br À in methanol solution, was carried out at 303 K. The formation constants and the individual calculated electronic spectra of each species in methanol solution were obtained. The obtained formation constants for the copper(II)-1,3-propanediamine system are: log b 110 = 6.70 ± 0.06, log b 120 = 11.59 ± 0.09, while for the ternary-chloro orbromo complexes are log b 111 = 10.23 ± 0.06 and log b 111 = 10.39 ± 0.02, respectively. On the other hand, for the copper(II)-1,4-butanediamine system are log b 110 = 7.44 ± 0.04, log b 210 = 11.07 ± 0.04, log b 120 = 11.86 ± 0.05, log b 230 = 22.53 ± 0.09, though for the ternary systems copper(II)-1,4-butanediamine-chloro or -bromo, the formation constants cannot be determined.

- by Majid Rezaeivala
- •
- Inorganic Chemistry, Speciation, Catalysis, Kinetics
- by Carole Prost
- •
- Tandem Mass Spectrometry, Spectrum, Analytical Method, Maillard reaction

The dissertation investigates the production of nanocomposites based on graphene oxide with a productivity of 100 kg/year. Corrosion, anti-corrosion substances - inhibitors, and the proporties of graphene oxide are all discussed in the introduction part. In the first chapter, the articles published before 10-15 years are reviewed and the materials were chosen and analyzed according to the existing topic. In the second chapter, the experimental methods were used to investigate the anti-corrosive, physicochemical properties of nanocomposite materials based on graphene oxide. In the third chapter, the materials which include nanocomposite materials based on graphene oxide were discussed briefly. The amount of the components consumed was calculated due to their productivity and all the data were written in the table. After that, the productivity of the equipment was defined based on its productivity. Finally, heat balance of the equipment was funded out based on its amount. At the end of the work, the results and recommendations based on the research were noted.

Three model metal complexes: Ni(NCS)L, Zn 2 (NCS) 2 L 2 and Cd 2 (NCS) 2 L 2 , consisting of the SCN À anion(s) and L = 2-[(2-dimethylaminoethylimino)-methyl]-phenolate, have been studied by X-ray diffraction and solid state NMR spectroscopy. The metal cations in these complexes have different coordination modes: Ni 2+ is almost square-planar, the Zn 2+ cation in Zn 2 (NCS) 2 L 2 is pentacoordinated, whereas Cd 2+ is pentaand hexacoordinated in [Cd 2 (NCS) 2 L 2 ]. The different coordination of the metal cations influences the chemical shifts of the metal cations and also the nitrogen atoms. These chemical shifts can be correlated with the M-N and M-O bond lengths (M = Ni 2+ , Zn 2+ , Cd 2+ ).

- by Beata Kołodziej
- •
- Inorganic Chemistry, Solid State NMR, X Rays, Metal Complexes

Sonochemical synthesis, DNA binding, antimicrobial evaluation and in vitro anticancer activity of three new nano-sized Cu(II), Co(II) and Ni(II) chelates based on tri-dentate NOO imine ligands as precursors for metal oxides Three new nano sized Cu(II), Co(II) and Ni(II) complexes of imine ligand derived from the condensation of 2-amino-3-hydroxypyridine and 3-methoxysalicylaldehyde have been prepared and investigated using various chemical techniques such as NMR, elemental analysis, molar conductance, IR, electronic spectra, TGA and magnetic moment measurements. The obtained chemical analysis data showed that the synthesis of 1:1 (metal:ligand) ratio and octahedral geometry was proposed on the basis of magnetic moment and spectral data studies except the Cu(II) complex which is tetrahedral geometry. Nano-sized particles of the investigated complexes were prepared by sonochemistry method. Furthermore, metal oxides nanoparticles were gained by calcination of the prepared corresponding complexes at 500 °C and their structures were characterized by powder x-ray and transmittance electron microscopy. Moreover, the free ligand, its complexes and their metal oxides have been checked in vitro against a number of bacteria and fungi in order to assess their antimicrobial activities. In addition to that, DNA binding of the prepared complexes was tested by many routes such as electronic spectra, viscosity and gel electrophoresis. The results showed that the investigated complexes could bind to DNA via an intercalative mode. The cytotoxicity of the Schiff base complexes on human colon carcinoma cells, (HCT-116 cell line) and Breast carcinoma cells, (MCF-7 cell line) showed potent cytotoxicity effect against growth of carcinoma cells compared to the clinically used Vinblastine standard.

- by Ahmed Mohammed Abu-dief Mohammed
- •
- Schiff Base, Anti-cancer

4-Phenyl-5-pyridin-4-yl-4H-1,2,4-triazole-3-thiol (3) was obtained in basic media via the formation of 2-isonicotinoyl-N-phenylhydrazinecarbothioamide (2), and converted to some alkylated derivatives (4a,b) and Mannich base derivatives (5aec). 2-[(4-Phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]acetohydrazide (7) that was obtained by using compound 3 as precursor in two steps was converted to thiosemicarbazide derivative (8), Schiff base derivatives (9) and 5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-1,3,4-oxadiazole-2-thiol (10). Moreover, 5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-3-{[(2-morpholin-4-ylethyl)amino]methyl}-1,3,4-oxadiazole-2(3H )-thione (11) was synthesized via reaction of compound 10 with 2-(4-morpholino)ethylamine. The treatment of compound 8 with NaOH gave 4-(4-methylphenyl)-5-{[(4-phenyl-5-pyridine-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-4H-1,2,4-triazole-3-thiol (12), while the acidic treatment of compound 8 afforded 5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-2(4-methylphenyl)-amino-1,3,4-thiadiazole . N-Methyl derivative of compound 14 and a Mannich base derivative of compound 12 were synthesized from the reactions of these precursors with methyl iodide and methyl piperazine, respectively.

Synthesis of the carbothioamides (5, 13, 22) was performed starting from 3H-1,2,4-triazol-3-ones (2, 17) by several steps, and then, these carbothioamides was converted to triheterocyclic compounds incorporating 1,2,4-triazole, imidazole and 1,3-thiazol(idinone) moieties. The reaction of compound 2 with 3,4-difluoronitrobenzene afforded the 2-(2-fluoro-4-nitrophenyl) derivative, 10.

- by Sengul Karaoglu
- •
- Medicinal Chemistry, Antimicrobial activity, Schiff Base, Biological activity

Metal complexes of Schiff bases derived from 2-furancarboxaldehyde and o-phenylenediamine (L 1 ), and 2-thiophenecarboxaldehyde and 2-aminothiophenol (HL 2 ) are reported and characterized based on elemental analyses, IR 1 H NMR, solid reflectance, magnetic moment, molar conductance, and thermal analysis (TGA). The ligand dissociation, as well as the metal-ligand stability constants were calculated, pH-metrically, at 25 • C and ionic strength μ = 0.1 (1 M NaCl). The complexes are found to have the formulae [M(L 1 )(H2O)2](Cl)n·yH2O (where M = Fe(III), Ni(II), Cu(II); n = 2-3, y = 2-4); [M(L 1 )](X)2·yH2O (where M = Co(II), Zn(II), UO2(II), X = Cl, AcO or NO3, y = 1-3); [M(L 2 )2]·yH2O

- by Gehad Ahmed
- •
- Escherichia coli, Metal Complexes, TURKISH, Pseudomonas aeruginosa