Schiff Base Complexes Research Articles

Synthesis of Schiff Base Complexes of Lanthanides in Microwave Assisted via Eco Friendly Method

Some new Schiff base complexes of dysprosium derived from alpha napthyl amine with different benzaldehyde. Reactions were carried out under microwave conditions. The ligands and their dysprosium complexes show a good activity against the bacteria S.aureus E.coli and fungi Penicillium Crysogenum, Aspergillus niger. The Schiff bases and their dysprosium complexes show variable activity of inhibition on the growth of bacteria.

Spectral, Structural, and Antibacterial Study of Copper(II) Complex with N2O2 Donor Schiff Base Ligand and Its Usage in Preparation of CuO Nanoparticles

A new Schiff base complex, Cu(H2L)2 (H3L: 6,6 ′ -((1E,1 ′ E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol)), through the reaction of ligand H3L with Cu(NO3)2 3H2O, in the ratio of 2 : 1 in methanol solvent was prepared. The obtained ligand (H3L) was characterized by FT-IR, 13C NMR, 1H NMR and elemental analyses. Then its copper(II) complex was prepared and characterized by FT-IR spectroscopy, thermal studies, elemental analyses and single crystal X-ray diffraction. The X-ray crystallography revealed that the two H3L ligands in bidentate fashion coordinated to one copper center for producing Cu(H2L)2 complex. We used copper(II) Schiff base complex, Cu(H2L)2, for the preparation of CuO nanoparticles via solid-state thermal decomposition. The crystalline structure of the product was studied by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). XRD indicated that the new product was copper oxide. SEM image showed that the size of CuO nanoparticles was between 46 and 53 nm, and they had uniform shape. The antibacterial properties of the complex and ligand were also investigated. The results revealed that Schiff base complex showed higher biological activity than Schiff base ligand.

Palladium(II) Schiff base complex arrests cell cycle at early stages, induces apoptosis, and reduces Ehrlich solid tumor burden: a new candidate for tumor therapy.

Although many cancer drugs are clinically approved, they still suffer from no adequate efficiency or drug resistance, or bad side effects. Therefore, developing safer alternatives of competitive efficiency is needed. This study aimed to investigate, for the first time, the antitumor and apoptotic activities of palladium(II) 2-hydroxyimino-3-(2-hydrazonopyridyl)-butane complex against Ehrlich carcinoma. In vitro, EAC cells were incubated with the complex, and the cells' viability, caspase 8 activity, and cell cycle changes were evaluated. In vivo, eighty adult female Swiss albino mice were distributed randomly in the following groups (n = 10): Normal, EAC, EAC + Cisplatin, and four groups EAC + Complex as well as Normal + Complex. Bodyweight changes were noted. On day 22 mice were sacrificed. Tumors' volume and weight were recorded. Blood picture was routinely investigated. The median survival time (MST) and percent increase in life span (%ILS) were monitored. In vitro, the complex reduced the %viable EAC cells, increased caspase 8 activity, arrested cell cycle at G0/G1, and reduced G2(M) population indicating antiproliferative and antitumor activities via inducing apoptosis. Treatment with the complex in a dose-dependent mode significantly decreased tumor volume and weight, extended the MST and the %ILS, increased mice body weight gain, and improved the blood indexes. Treatment of EAC-bearing mice with the complex highest dose showed more desirable outcomes than treatment with cisplatin. The Normal + Complex group showed no pathological changes indicating safety. In conclusion, our outcomes recommend the Pd(II) complex as a new optimistic candidate for tumor therapy after further studies for validation.

Synthesis and physicochemical characterization of Schiff base complexes and examination of their selectivity index for breast and colon cancer cells.

Synthesis and physicochemical characterization of Schiff base complexes and examination of their selectivity index for breast and colon cancer cells.

Statement of Retraction

This article refers to:RETRACTED ARTICLE: A molybdenum Schiff base complex: repairing activity on orthodontics-related root absorption by reducing the TNF-α releasing

Structural investigations and catalytic performances of a new oxovanadium complex derived from 1,2-bis((E)-5-bromo-2-hydroxybenzylideneamino)-4-methylbenzene

A new unsymmetrical oxovanadium Schiff-base complex VOL was prepared by using stoichiometric amounts of Schiff-base ligand 1,2-bis((E)-5-bromo-2-hydroxybenzyl-ideneamino)-4-methylbenzene and VO(acac)2. Characterization of the ligand H2L and the corresponding VOL complex were performed using elemental analysis, spectroscopic methods as FT-IR, UV-Vis, 1H and 13C NMR. The VOL complex crystallizes, in the monoclinic crystal system, with P21/c space group. All experimental results were proved and explained theoretically exploiting Density Functional Theory calculations, DFT. Molar conductance measures confirmed the non-electrolytic nature of the metal complex. Similarly, the electrochemical behavior for both the ligand and the VOL complex have been investigated by cyclic voltammetry, CV. The complex gave a one-electron quasi-reversible redox couple at +568 mV/SCE corresponding to the VOIV/VOV redox process. The various inter contacts present within the crystal were visualized through 3D molecular hirshfeld surface analysis and their percentage contribution towards the total hirshfeld surface area has been quantized using 2D finger print plot method.The catalytic performances of the VOL complex in the epoxidation of cyclohexene were explored by various reaction parameters including temperature and solvent effects, oxidant, cyclohexene/oxidant ratio and the catalyst amount. The results show that the system corresponds to an active and a selective catalyst in the oxidation of cyclohexene. Superb catalytic activity of 98% cyclohexene conversion with 86% cyclohexene oxide selectivity were obtained over 5h.

Dioxo-molybdenum(VI) unsymmetrical Schiff base complex supported on CoFe2O4@SiO2 nanoparticles as a new magnetically recoverable nanocatalyst for selective epoxidation of alkenes

Dioxo-molybdenum(VI) unsymmetrical Schiff base complex supported on CoFe2O4@SiO2 nanoparticles as a new magnetically recoverable nanocatalyst for selective epoxidation of alkenes

Functional Disruption of Gli1-DNA Recognition via a Cobalt(III) Complex.

The aberrant activation of the Gli family of zinc finger transcription factors (ZFTFs) is associated with several types of human cancer, including medulloblastoma and basal cell carcinoma. We have reported the use of cobalt(III) Schiff-base complexes (Co(III)-sb) as potent inhibitors of ZFTFs in vivo. These complexes inhibit transcription by displacing the zinc finger domain's structural Zn(II) ion, destabilizing the alpha helix necessary for DNA recognition. Here, we describe the use of Co(III)-sb complexes for the selective inhibition of Gli1. Spectroscopic and computational studies of the Gli1 DNA binding domain found that Co(III)-sb displaced Zn(II) through direct coordination with the His residues of the Cys2 His2 Zn(II) binding site. As a result, there is a dose-dependent degradation of the alpha-helix content in the DNA binding domain of Gli1 and corresponding inhibition of consensus sequence recognition. We conclude that this strategy is well suited for the development of new and potent inhibitors of Gli1.

Synthesis and Spectral Characterization of Novel Schiff Base and Fe(II) Complex: Evaluation of Antibacterial, Antifungal, and Anticancer Properties

Schiff’s bases are a type of molecule found in medical chemistry that has been shown to have substantial antibacterial and chemotherapeutic properties. On the other hand, Ortho phenylenediamine is a broad category of synthetic chemical with various pharmacological properties, including anticancer potential. Their antibacterial, antifungal, and anticancer properties, in particular, make the compounds appealing for future derivatization and screening as potential therapeutic agents. Accordingly, this study aimed to synthesize a novel Schiff’s base-Fe(II) complex using the self-assembly method for in-vitro studies due to its potential drug properties for therapeutic intervention in various diseases. The as-synthesized Fe(II) complex was characterized by spectral and elemental techniques. The obtained data from the elemental analysis was in good agreement with the general formula MLCln (L= Ligand complexed with Fe(II) via carbonyl group, the nitrogen of hydrazine group, and oxygen). Additionally, Fe(II) complexes with Schiff’s bases were shown to have gastro-protective, antiproliferative, and antibacterial properties. The Schiff’s base and its Fe(II) complex were screened against gram-positive (B.subtilies), gram-negative (E.coli) as well as A.niger to evaluate the antibacterial and antifungal properties, respectively. The obtained results demonstrated that the Schiff’s base –Fe(II) complex has higher antibacterial and antifungal activity than Schiff’s base ligand. Furthermore, cytotoxicity studies were performed for Schiff base and its Fe(II) complex against breast cancer (MCF-7) cell lines. The findings of this study recommended new insights in the field of medicine to consider Schiff’s base-Fe(II) complex as a potential candidate for the antibacterial, antifungal, and anticancer agent.

An effortless approach to synthesize two structurally diverse nano copper(II) materials and assessment of their apoptosis‐inducing ability on lung cancer cell line

AbstractTwo architecturally dissimilar coordination complexes, namely, C1 = [CuL1(NO2)]2 and C2 = [CuL2(NO3)] (L1 = (4‐bromo‐2‐[(2‐isobutylaminoethylimino)methyl]phenolate and L2 = (4‐bromo‐2‐[(2‐propylaminoethylimino)methyl]phenolate) have been synthesized from two different organic ligand backbones. The synthesized complexes have been identified using some common techniques like elemental analysis, FT‐IR spectroscopy, and single‐crystal X‐ray analysis. The X‐ray structural analysis revealed that C1 is a dinuclear complex realized through one bridging nitrite anion, whereas for C2, nitrate anions bridge the complexes to accomplish a 1D coordination polymer. C1 and C2 when slashed down by rapid and green mechanical method by using a simple hand grinding technique, mortar and pestle, resulted in NC1 and NC2 nanoparticles, whose average size was characterized by PXRD, SEM, and DLS.As far as we know, this is the first report where the nano‐formulation has been used while maintaining the structural integrity of the Schiff base complex. The proliferative properties of these complexes have been assessed in vitro using human lung carcinoma cell line A549. Being a polymer, the number of metal centers in NC2 is much higher; accordingly, this complex is more vital in terms of biological activity in comparison with NC1.

Luminescence of Zn-Yb dinuclear Schiff base complex: Enhanced NIR emission by modification with larger conjugated light-harvesting moieties

The fundamental challenge for the highly efficient NIR-luminescence of lanthanides is to identify the suitable chromophores as sensitizer. Herein, the first Salen-type Schiff base ligand modified by conjugated fluorene has been designed to enhance the near-infrared emission of the ytterbium complex. The photophysical properties reveal the potential of the Schiff base dyes as an efficient and strong visible light sensitizer for the lanthanide-based NIR emitters. The modified rigid Schiff base ligand is noted to encapsulate the Ln3+ ions as it prevents the coordination of the solvent molecules, thus, tending to quench the luminescence phenomenon. Due to the intermolecular π-π interactions, the excited state energy levels of ligands are observed to reduce, thus, leading to the highly efficient energy transfer from the triplet state of ligands to the Yb3+ ions. In addition, the shifting of the absorption wavelength of the complex towards low energy (450 nm) makes it suitable for biomedical applications. Further, the ytterbium complex exhibits the highest intrinsic quantum yields (3.68%) among the Salen-type ytterbium complexes.

Selective oxidation of benzylic alcohols using Mo(VI) Schiff base complex supported on magnetic nanoparticles as a new recoverable heterogeneous catalyst

Selective oxidation of benzylic alcohols using Mo(VI) Schiff base complex supported on magnetic nanoparticles as a new recoverable heterogeneous catalyst

An Updated Perspective of Nano Schiff Base Complexes: Synthesis, Catalytic, Electrochemical, Optical, Crystalline Features and Pharmacological Activities

An Updated Perspective of Nano Schiff Base Complexes: Synthesis, Catalytic, Electrochemical, Optical, Crystalline Features and Pharmacological Activities

Synthesis, characterization, DFT calculations, and catalytic epoxidation of two oxovanadium(IV) Schiff base complexes

The present paper reports the synthesis, characterization, and DFT calculations of two oxovanadium (IV) Schiff base complexes symbolized as VOL1 and VOL2, which prepared by the reaction of bivalent tridentate Schiff base ligands (E)-2-((5-chloro-2-hydroxybenzylidene)amino)acetic acid and (E)-2-((2-hydoxy-5-nitrobenzylidene)amino)acetic acid and VO(acac)2 as vanadium source. The Schiff base ligands and its oxovanadium (IV) complexes were characterized by the elemental analysis (C, H, N), FTIR, 1H NMR and 13C NMR, DFT calculations were performed to derive some of their molecular properties. Schiff base ligands coordinated to vanadium center via nitrogen from the azomethine group and one oxygen from the hydroxyl attached to the benzene ring and one oxygen from hydroxyl of carboxyl group. The catalytic activity of the two complexes were tested against cyclooctene and found that both complexes were highly effective and selective in optimized conditions when used as cyclooctene epoxidation catalysts with the conversion percentage of 91.85% (with VOL1) and 87.40% (with VOL2) at 78 °C within a period of ten hours. To understand the structural properties of the two complexes, the two complexes were well optimized at B3LYP/6-31G(d,p) level of theory, structural parameters such as electron affinity, global electrophilicity, global hardness, electronegativity, ionization potential, and electron chemical potential based on HOMO and LUMO energy values were calculated.

Zinc Donor–Acceptor Schiff Base Complexes as Thermally Activated Delayed Fluorescence Emitters

Four new zinc(II) Schiff base complexes with carbazole electron donor units and either a 2,3-pyrazinedicarbonitrile or a phthalonitrile acceptor unit were synthesized. The donor units are equipped with two bulky 2-ethylhexyl alkyl chains to increase the solubility of the complexes in organic solvents. Furthermore, the effect of an additional phenyl linker between donor and acceptor unit on the photophysical properties was investigated. Apart from prompt fluorescence, the Schiff base complexes show thermally activated delayed fluorescence (TADF) with quantum yields up to 47%. The dyes bearing a phthalonitrile acceptor emit in the green–yellow part of the electromagnetic spectrum and those with the stronger 2,3-pyrazinedicarbonitrile acceptor—in the orange–red part of the spectrum. The emission quantum yields decrease upon substitution of phthalonitrile with 2,3-pyrazinedicarbonitrile and upon introduction of the phenyl spacer. The TADF decay times vary between 130 µs and 3.5 ms at ambient temperature. The weaker phthalonitrile acceptor and the additional phenyl linker favor longer TADF decay times. All the complexes show highly temperature-dependent TADF decay time (temperature coefficients above −3%/K at ambient conditions) which makes them potentially suitable for application as molecular thermometers. Immobilized into cell-penetrating RL-100 nanoparticles, the best representative shows temperature coefficients of −5.4%/K at 25 °C that makes the material interesting for further application in intracellular imaging.

Novel oxo–peroxo W(VI) Schiff base complex: synthesis, SC-XRD, spectral characterization, supporting on chloromethylated polystyrene, and catalytic oxidation of sulfides

Novel oxo–peroxo W(VI) Schiff base complex: synthesis, SC-XRD, spectral characterization, supporting on chloromethylated polystyrene, and catalytic oxidation of sulfides

Development of a novel electrochemical nitrite sensor based on Zn‐Schiff base complexes

A novel electrochemical sensor for the determination of nitrites based on the modified screen‐printed electrode (SPCE) by Zn‐bidentate Schiff base complexes (ZnLX2) is presented. ZnLX2 complexes have been synthesized and characterized using several morphological and microstructural techniques such as scanning electron microscopy (SEM), X‐ray powder diffraction (XRD), and fourier transformed‐infrared (FT‐IR) spectroscopy. Cyclic voltammetry (CVs) proved the good electrochemical performances of the ZnLX2/SPCE for nitrite ions determination. The influence of pH, scan rate, nitrite concentration, and interfering ions was investigated. After optimization of the operating parameters, the developed ZnLX2/SPCE sensor displayed two linear relationships between response current and nitrite concentration in the overall range 2–4838 μM and a lower detection limit estimated to be 0.78 μM based on 3σ/m. Finally, the analytical application of the developed sensor was evaluated to quantify nitrite in a real sample of mineral water. Results obtained demonstrate that the ZnLX2/SPCE electrochemical sensor provided an effective tool for the detection of nitrite ions.

Experimental and computational studies on copper(II) Schiff base complex derived from 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one

A new tetradentate N2O2 type Schiff-base ligand (H2L) was synthesized from the condensation of 4-acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one with 2,2-dimethyl-1,3-propanediamine. The corresponding Cu(II) complex (CuL) was also synthesized. The ligand and the complex were characterized by FTIR and UV-Vis spectroscopy and elemental analysis. 1H- and 13C NMR spectra of the ligand and X-ray crystal structure of the complex were obtained. The main non-covalent intermolecular interactions were studied by Hirshfeld surface analysis and finger print plots. Due to the different structural possibility including imine‐one, amine‐ol, and amine-one forms for H2L compound, their conformational and geometrical aspects were investigated computationally by DFT/ M06-2X-6-311+G(d,p) methods. The computational results suggested that the amine-one is the most favorable tautomeric form.

Synthesis, crystal structure, spectral characterization, theoretical studies, and investigation of catalytic activity in selective oxidation of sulfides by oxo-peroxo tungsten(VI) Schiff base complex

A novel oxo–peroxo tungsten(VI) Schiff base complex, [WO(O2)L(CH3OH)], a homogeneous catalyst for sulfoxidation was synthesized by treating WO3 in the presence of H2O2 with a dibasic tridentate (ONO) Schiff base ligand. The complex was characterized by FT–IR, 1H NMR, and 13C NMR spectroscopy. Moreover, the structure of the crystalline tungsten(VI) complex was further investigated by single crystal X-ray diffraction analysis (SC-XRD). The crystal structure analysis revealed that the complex is hepta-coordinated, and metal ion is surrounded by ONO set of the coordinated doubly deprotonated ligand to adopt a distorted pentagonal–bipyramidal geometry. The theoratical calculations of the geometrical parameters, frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), and natural bond orbital (NBO) analysis of the synthesized compounds utilizing DFT at the B3LYP level of theory at the Def2-TZVP basis set revealed that the predicted data match the experimental results. The main purpose of the current study is to employ the synthesized W complex for its homogeneous catalytic effectiveness for the oxidation of aryl and alkyl sulfides in ethanol by using 30% aqueous H2O2.

Synthesis, Spectroscopic Characterization and Pharmacological Significance of Schiff Base Complex

The Schiff base ligand and the Metal complex have been characterized by elemental analysis IR, UV-visible, NMR, conductivity measurements. The Molar conductance of Mn(II) complex showed non- electrolyte in nature. The spectroscopic data of metal complex indicated that the metal ion is complexed with azomethine nitrogen and the complex exhibit octahedral arrangements. The entire complex exhibited more antimicrobial than ligand Further the metal complex screened for cytotoxic studies against a panel of human cancer lines.