جستجوی مقالات مرتبط با کلیدواژه « Schiff-base » در نشریات گروه « شیمی »

Synthesis of new Schiff base ligand [(Z)-4-(((1H-1,2,4-triazol-3-yl)imino)methyl)-2-methoxyphenyl dihydrogen borate] (L) by reaction of boron derivative of vanillin ( 4-formyl-2-methoxyphenyl dihydrogen borate) with 3-amino-1,2,4-triazole was carried on in a 1:1 mole ratio. In addition, the complexes of metal Co(II), Ni(II), and Cu(II) were characterized. Each compound was characterized using spectroscopic techniques such as FT-IR, 1H-NMR, and UV-Vis spectrometry. Furthermore, the following analytical techniques were employed: thermal analysis (TG), atomic absorption spectroscopy (AAS), elemental microanalysis (C.H.N), measurements of the melting point, chloride analysis, magnetic sensitivity testing, and molecular conductivity tests. All of the complexes exhibited non-electrolytic behavior and their indicated geometrical shapes were octahedral. All compounds exhibited paramagnetic magnetic characteristics. The synthesized compounds possessed a good efficiency as antimicrobial activity (anti-bacterial and anti-fungal) against Escherichia coli (Gram-negative), Staphylococcus aureus (Gram-positive), and Candida albicans. The synthesized compounds were assessed as an in vitro anti-cancer agent against human thyroid carcinoma (FTCI33), the result showed that the copper complex was more effective compared to ligand and its other complexes.

A new Schiff base (5) was synthesized by reacting the hydrazide derivative (3) with p-aminoacetophenone in the presence of a few drops of H2SO4 in ethanol as a solvent. Following this preparation, the diazonium salt was prepared by reacting compound (6) with sodium nitrate in the presence of HCl at 0-5 °C and performing a coupling reaction. This reaction involved the prepared diazonium salt and some substituted phenols, leading to the formation of the corresponding azo-Schiff bases 7(a–e). Target compounds were identified using FT-IR, 1H-NMR and 13C-NMR. The second part of the current work includes the investigation of molecular docking and biological activities such as antimicrobial and antifungal effects.

In this research, fluorescein-based chemical sensors were designed and synthesized through the Schiff base reaction to identify Cu2+ and Hg2+ cations. For this purpose, at first SP1 and SP2 sensors were synthesized and their structures were investigated and confirmed by 1HNMR and MS spectroscopy methods. Then, their properties as chemical sensors for some metal cations were investigated by fluorescence emission spectroscopy and ultraviolet-visible spectroscopy (UV-Vis). The obtained results indicated that the SP1 and SP2 acted selectively and also showed a color change for Cu2+ and Hg2+ cations, respectively. The reversibility studies in the presence of EDTA showed that the fluorescence was turned on with the addition of the extra amounts of Cu2+ and Hg2+ cations. Also, the data obtained from Job’s graph and fluorescence titration determined that both sensors form complexes with cations in a ratio of 1:1. Since the structures of both SP1 and SP2 are rigid, the fluorescence turned on with a plausible CHEF mechanism.

In the present work (E)-4-((4-(benzyloxy) benzylidene) amino)-N-(5-methylisoxazol-3-yl) benzenesulfonamide (L1) and (E)-N-(5-methylisoxazol-3-yl)-4-((4-nitrobenzylidene) amino) benzenesulfonamide (L2) have been successfully prepared in alcoholic medium with Hydrochloric acid HCl as a catalytic agent. L1 and L2  have been characterized by elemental analysis, FT-IR, 1H NMR, 13C-NMR, SM, and UV-visible spectroscopy. Theoretical calculations were performed at the DFT level of theory using the B3LYP functional and the 6-31G (d, p) basis set, and electronic properties were calculated using the Time-Dependent Density Functional Theory (TD-DFT) method. In addition to the optimized geometrical structure, Frontiers molecular orbital HOMO/LUMO and NBO charges have been investigated to describe the chemical reactivity of the compounds. The vibrational wavenumbers were calculated and they correlated well with the experimental data. The antibacterial activity of the ligands was tested. The results revealed that the synthesized compound exhibited good to moderate antibacterial activity. Furthermore, interactions between synthesized compounds and bacterial proteins were evaluated by molecular docking while pharmacokinetics and toxicity were studied by ADMET analysis.

This study focuses on investigating the complexation process between N,N'-bis(salicylidene)ethylenediamine (Salen) and the metal complex [Cu(PDTC)2] in a dimethyl sulfoxide (DMSO) solvent. The kinetics and thermodynamics of the substitution reaction were examined. The [Cu(PDTC)2] complex and the Salen ligand were synthesized using a reported method, and their absorption spectra displayed characteristic peaks consistent with previous findings. The kinetics of the Cu(II) complex were studied under pseudo-first-order conditions in DMSO, with varying concentrations of Salen and a constant concentration of the [Cu(PDTC)2] complex. Reactions were carried out at temperatures of 25 °C, 30 °C, and 35 °C. By conducting temperature-dependent studies, the activation parameters (activation energy, activation entropy, and activation enthalpy) were determined. The substitution reaction was monitored through absorption spectra measurements, revealing a reduction in the absorption peak at 435 nm and the appearance of a new absorption peak at 360 nm. The rate constants obtained for the substitution reactions of salen at 25 °C fell within the range of 0.16x10-1 1/min to 5.66x10-1 1/min, which was higher compared to previous investigations due to the size of the substituted ligand. The reaction was found to follow the first-order kinetics with respect to [Cu(PDTC)2] and salen, indicating a second-order overall reaction. Increasing temperature resulted in higher values of kobs and k2. The calculated activation parameters revealed a positive activation entropy, implying a dissociative mechanism, and a positive activation enthalpy, indicating an endothermic nature of the substitution reaction.

The worthwhile contributions made to the literature by researchers on the ligation behaviour of Schiff bases derived from anthranilic acid and their applications is hitherto not togetherized. This review covers a comprehensive bibliographic perusal of anthranilic acid-derived Schiff bases and their chelates reported circa over the last three decades (1990 - 2022) with a view to furnishing information that will help researchers in the design of new Schiff bases as potential candidates in different applications. A scrupulous survey of the literature suggests that anthranilic acid-derived Schiff bases preferentially ligate metal ions through azomethine nitrogen (-N=CH-) and the hydroxyl oxygen (OH) of the carboxyl group after deprotonation rather than chelating via the carbonyl oxygen (C=O). However, a pocket of the literature reported the coordination sites as the iminic nitrogen (-N=CH-) and carbonyl oxygen (C=O) of the carboxylic group. While most first row transition metals complexes of diverse geometries with the Schiff bases' denticity ranging from N,O-bidentate, O,N,O-tridentate and N2O2-tetradentate amongst others have been documented, only few heavier transition metals are reported. Furthermore, these Schiff bases find promising applications in medicinal, pharmaceutical, catalytic, and analytical chemistry, especially in the seperation, identification, and detection of several metal ions and anions. In addition to these, they are used as corrosion inhibitors, as odorants, etc. Notably, the chelates more often exhibited more potency as antibacterial, antifungal, anticancer, antidiabetic, antioxidant, antioxidant, antiulcer and molluscicidal agents than the free Schiff base ligands. This review exhaustively did synthesized most significant works on the subject.

In the present study, the Schiff base was synthesized [1,1'-((1E,1'E)-((4,5-dimethyl-1,2-phenylene)bis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol) ] derived from the reaction of 2-hydroxy-1-naphtha-aldehyde with, 4,5-Dimetyl-1,2-penylenediamine for 4hr. and yield was 90.09%. The prepared compound was identified by C.H.N, UV-Vis, FT-IR 1H–NMR, and mass spectroscopy and was studied also theoretically using Gaussian 09 software based on the DFT method at B3LYP/6-31G (d,p). Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies that were conducted experimentally. The weight loss method was used to measure the efficiency of the prepared compound as a corrosion inhibitor in an acid medium. It was found that the inhibition efficiency was increased with decreasing temperature and the concentration increase of synthesized Schiff base and the highest inhibition efficiency was obtained at an optimum concentration of (1×10-3 M) for inhibitor at 298 K. Moreover, it was found that the adsorption process of the inhibitor on the surface of the brass is obeyed by the Langmuir isotherm of adsorption. The value of the free energy change was found to be -28.28 kJ/mol, which indicates that the prepared compound adsorbed on the surface of the metal. The antioxidant activity of the prepared Schiff base was investigated on the basis of the radical scavenging effect of 1,1-diphenyl-2-picryl-hydrazyl (DPPH)-free radical activity was also studied. The ligand (S1) exhibited excellent activity.

In this article, a Schiff base ligand was produced with Co (II) and Ni (II) complexes. The Schiff base was prepared by the condensation reaction between 9,10-phenanthrynquinone and 2-mercaptoaniline in a ratio of 1:1, respectively, and the reaction time was  three hours. While the Co (II) and Ni (II) complexes were prepared by reacting the prepared Schiff base ligand with the metal chloride salts in ethanol also in 1:1 molar ratio of L:M and the synthesis time 12 hours. The produced ligand was characterized by infrared spectroscopy, UV-Vis, 1H-MNR, mass spectroscopy, and thermal gravimetric analysis, while the complexes were also characterized by UV-Vis spectroscopy, FTIR, conductivity measurements, atomic absorption, magnetic susceptibility, and thermal gravimetric analysis. The resulted complexes were green in color. Based on the results, the coordination between the metal ions and the Schiff base occurs through the imine group of the Schiff base ligand, the thione group and the remaining oxygen atom of 9,10-phenanthrynquinone. While the conductivity test shows that the two complexes are non-electrolyte in nature where ethanol was used as a solvent. The magnetic susceptibility values of Co and Ni (II) complexes were found to be 3.09 and 3.3 7 BM, respectively which indicate the presence of three unpaired electrons and two unpaired electrons in both complexes, respectively. These values also support the octahedral geometry of the higher spin complexes and confirm the sp3d2 metal hybridization in the complexes. The atomic absorption values of the complexes and the thermogravimetric analysis confirm that the proposed structure for the complexes is [M(L)ClH2O)]XH2O.

In this paper, a new aprotic N2O2-tetradentate Schiff base ligand and its mercury complexes were synthesized with a general formula of HgLX2 (X is Cl−, Br−, I−, N3−, NO3− and SCN−) and characterized by physical and spectral techniques such as IR, UV-Visible, 1H NMR, 13C NMR, ESI/MASS, molar conductivity, thermal analysis and melting point. In addition, nanostructured HgLI2 and HgLBr2 complexes were also synthesized and confirmed using SEM, EDX and XRD techniques. Thermal analysis of the ligand and complexes showed that these compounds decompose in 2-3 steps. Moreover, some thermo-kinetics activation parameters of the compounds were calculated at all the thermal decomposition steps. The biological properties of synthesized compounds were tested against two gram-positive and two Gram-negative bacteria. Also, Aspergillus oryzae and Candida albicans were selected for antifungal screening of the compounds. Further, the bactericidal effects of the compounds were depicted by SEM images of treated bacteria by the ligand and some mercury complexes. The ability of DNA cleavage of N2O2-tetradentate Schiff base ligand and its complexes was investigated by the agarose gel electrophoresis method. The results showed that Schiff base mercury complexes had higher antibacterial/antifungal activity as compared with the free ligand. HgLX2 compounds also showed a greater ability to cleavage of DNA than free ligand. Furthermore, the cytotoxicity properties of the ligand and some HgLX2 (X=Cl−, Br− and I−) complexes were evaluated against the PC3 cancer cells line by using MTT bioassay and nitric oxide level measurement as compared with cisplatin. Finally, the antioxidant activities of the titled compounds were measured by DPPH and FRAP methods.

The bidentate Schiff-base ligand, N,N'-bis((E)-3-phenylallylidene)-4-nitro-1,2-phenylenediamine, [L], was synthesized and characterized along with its Cu(II) complexes, CuLX2 (where X = Cl and Br). The characterization involved elemental analysis, 1H NMR, 13C NMR, FT-IR, and UV-Vis spectroscopy, as well as thermal and conductivity studies. The elemental analyses of these complexes were consistent with the stoichiometry of the type CuLX2. The confirmation of their stabilization and their slight electrolytic nature is reinforced by their low molar conductivity. Furthermore, the alterations in both the location and shape of the peaks in the UV-Vis and FT-IR spectra of the complexes, relative to those of the free ligand, serve as additional evidence supporting the formation of Schiff-base complexes. Also, cathodic and anodic shifted in the potential’s peaks of complexes compared to free ligand approve formation of compounds. Catalytic activity of these complexes in the room temperature deoximation using sodium periodate were studied. Obtained aldehydes and ketones as single products in excellent yields confirm catalytic activity of these complexes. Lastly, in vitro cytotoxic features of all samples studied against A549 and HT29 cancer cell lines and the outcomes exhibited excellent cytotoxic potential of synthesized complexes.

Two new Cu(II) complexes, [Cu(L22py)Cl]ClO4 (1), Cu(L22pysa) (2), {L22py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane, were prepared through the reaction of suitable metal ion salts, L22py, and salicylaldehyde in the presence of NaClO4. The ligands were characterized by elemental analysis, IR spectroscopy, and 13C and 1H NMR analysis. Additionally, X-ray crystal structure analysis was performed for complex 1. The X-ray study revealed that the Cu(II) ion exhibits a square configuration.

In this work, new 1,3-oxazepine derivatives were synthesized from a Schiff base. The latter was prepared by reacting 4-amino antipyrine with 4-amino acetophenone, then the Schiff base, which has an amine group, reacted with maleic anhydride to produce the corresponding amic acid. The prepared amic acid compound has an azomethine group utilized in synthesizing new derivatives of 1,3-oxazepine through reacting the amic acid with different cyclic anhydrides (succinic anhydride, maleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, and citraconic anhydride). Different techniques have been used to confirm the structures of synthesized compounds in terms of physical properties and spectroscopic measurements, where proton nuclear magnetic resonance 1H-NMR and Fourier Transform Infrared FT-IR spectroscopies have been used to confirm the synthesized compounds. In addition, the antibacterial activity of oxazepinederivatives was examined against two types of bacteria, gram-negative and gram-positive.

Schiff base-inorganic complexes have significantly contributed to the development of modern drug design due to their significance in a number of multi-discipline study fields. This nearly exhaustive review examines every aspect and characteristic of these complexes, with a focus on a few key biomedical traits. Schiff base, the organic component of these complexes, is formed by the condensation of two important molecules: a carbonyl and a primary amine framework. Organic compounds based on the Schiff base moiety have been demonstrated to have biomedical attributes such as antibacterial, antioxidant, antifungal, antineoplastic, and antiviral properties. In the light of these attributes and the recent advances in the domain of coordinating chemistry, many research outcomes suggest the Schiff base-inorganic complexes as a potential core for medicinally active coordinated compounds and for reaction catalysis. This suggestion is supported by numerous new research findings that document the properties of these complexes as antimicrobial, antioxidant candidates, and efficient promoters in various chemical reactions.

A new Schiff base ligand bound to ionic liquid and crown ether was synthesized and complexed with Mn (III) metal. Manganese complex was used in the vicinity of oxone oxidant and the absence of an axial base in water-chloroform biphasic oxidation to oxidize different alkenes, the corresponding epoxides were obtained with 70-96% yields. The lowest efficiency is related to alkenes with electron-withdrawing groups.

Schiff base was reacted with α-chloroacetic acid to produce N-(α-chlorobenzyl)-N-phenylglycine derivatives (N-Gly) over solid heterogeneous catalyst. Different N-Gly derivatives were synthesized over the catalyst with approximately 90% yield. Both calculated and theoretical elemental analyses of N-Gly derivatives were in agreement with each other. The functional groups of N-Gly derivatives were proved by the FT-IR spectroscopy. The melting points N-Gly derivatives were matched with those in the literature. The catalyst was produced by immobilizing sodium silicate from rice husk with 3–(chloropropyl)triethoxysilane followed by refluxed the product with p-xylyl-di-imidazolium chloride. The results showed that the optimum catalyst conditions were 5 h as reaction time, 0.25 g mass of catalyst, 90 °C as reaction temperature, and toluene as the best solvent.

Herein, five Schiff base molecules derived from para-nitrobenzaldehyde and different aniline derivatives are studied theoretically from the structure and energy perspectives. Density functional theory DFT method with 6-31+g(d,p) basis set is utilized to determine the optimized structure with the lowest energy in terms of the internal coordinates such as bond lengths, bond angles, and torsion angles. The study includes investigating the electronic indicators of the title molecules, such as frontier molecular orbital, electron affinity, ionization potential, and other parameters to predict the sites of reactivity and obtain an insight of the main properties of the molecules. Moreover, the electrostatic potential maps were determined and illustrated for the studied compounds to investigate the reactivity of charges on the surface of the molecules whether being of an electrophilic or nucleophilic nature. The study aims to examine the effect of changing the functional group in para-location of the aniline moieties on the molecular and geometrical properties of the molecules.

In this work, 2-amino pyridine was mixed with biphenyl bromide under refluxed to give the product of 2-biphenyl imidazo [1,2-a] pyridine (1). Compound (1) was treated with 4-amino acetophenone with formaldehyde dissolved in absolute ethanol to yield Mannich base (2). Schiff bases [3I-3K] were also prepared by condensed compound (2) dissolved in absolute ethanol with few drops of glacial acetic acid and different aromatic amines. After that, Schiff bases were cyclized using three reagents such as marcapto acetic acid, succinic anhydride, and 3-Nitrophthalic anhydride dissolved in absolute ethanol under refluxed at certain temperature to form thiozolidinone (4I-4K), (1,3)oxazepine-4,7-dione (5K-5I) and 4-Nitro benzo (1,3) oxazepine-4,7-dione (6I-6K) compounds. All compounds were characterized by FT-IR, 1H-NMR, and 13C-NMR spectra. Some new compounds were evaluated as antioxidant and anticorrosion agents.