Schiff Base Transition Metal Complexes Research Articles

Facile synthesis of ZnO nanoparticles by thermal decomposition of Schiff base complexes for the effective removal of organic pollutants in an aqueous medium

A series of mononuclear Schiff base transition metal complexes of the type [M(LS)(temed)] (where, M = Co(II), Ni(II), Cu(II), and Zn(II); LS = Schiff base ligand derived from L-leucine and Salicylaldehyde and co-ligand temed = N,N,N’N’- tetramethylethylenediamine) have been synthesized and characterized by spectroscopic studies such as Mass, NMR, UV–Visible, FT-IR, and TGA analysis. Spectral results reveal that the metal ions are coordinated to imine nitrogen, phenolic oxygen, and oxygen atom present in the carboxylate group of the Schiff base ligand and two nitrogen atoms from ligand (L2) temed. The scavenging activity of the complexes was carried out by the DPPH method with different concentrations, and all the complexes possesses good antioxidant activity in the range 58.93 to 78.79 %. Among them Zn(II) complex showed higher scavenging activity 78.79 % using 10 mg concentration. Furthermore, an investigation was conducted to assess the antibacterial properties of the complexes. It was observed that all of the metal complexes exhibited significant antimicrobial activity. Notably, the copper complex demonstrated enhanced activity, particularly against S. aureus and Mucor species, with zone of inhibition measurements of 19 mm and 20 mm, respectively. The Zn(II) complex has been used as a precursor to produce zinc oxide nanoparticles by the thermal decomposition method. ZnO nanoparticles have been characterized by powder X-ray diffraction (PXRD), UV–Vis spectroscopy techniques, scanning electron microscopy (SEM), FT-IR spectroscopy. The photocatalytic activity of zinc oxide nanoparticles was investigated in the presence of ultraviolet light. ZnO nanoparticles can efficiently catalyze the degradation of methyl orange, methylene blue, and rhodamine B in the aqueous suspension, and the highest percentage of degradation was observed against methylene blue (99 %). Furthermore, the impact of altering dye concentration, pH, catalyst quantity and kinetics on the photodegradation of model pollutant methylene blue was investigated.

Experimental and theoretical insight of Schiff base transition metal complexes: synthesis, characterization, antimicrobial and COVID-19 molecular docking studies

Experimental and theoretical insight of Schiff base transition metal complexes: synthesis, characterization, antimicrobial and COVID-19 molecular docking studies

Synthesis, Hirshfeld surface analysis, thermal, and selective α-glucosidase inhibitory studies of Schiff base transition metal complexes

Abstract A synthesized Schiff base ligand 4-{(Z)-[(2-hydroxy-1-naphthyl)methylene]amino}-4-antipyrene (H-NAPP) was confirmed by single crystal diffraction analysis. The H-NAPP was crystalized in the P 21 21 21 space group and orthorhombic crystal system. The Schiff base ligand H-NAPP bears potential donor sites and therefore it was reacted with transition metal ions Co2+, Ni2+, Cu2+, and Zn2+ to yield respective metal complexes. All reaction products were investigated by elemental analyses and IR spectroscopic techniques. The combined spectroscopic characterizations revealed the distorted square planar geometries for all the synthesized metal complexes. The metal complexes were further studied for their thermal stabilities using TG techniques and proved to be thermally cleaved in the temperature range of 30–1,000°C in air. Pseudo-mirrored 2D fingerprint plots were used for the short interatomic interactions in the crystal structure. The major short interatomic interactions involve the hydrogen bonding which covers the Hirshfeld surfaces {H···H, O···H and C···H}. The ligand and complexes were investigated for a potential α-glucosidase inhibitory activity. While relatively inactive throughout, some notable differences were observed and, surprisingly, the ligand was found to be more active than its complexes.

Statement of Retraction: Three novel Schiff base transition metal(II) complexes induce gastric cancer cell death through ROS-mediated apoptotic pathway

This article refers to:Three novel Schiff base transition metal(II) complexes induce gastric cancer cell death through ROS-mediated apoptotic pathway

Novel Schiff base transition metal complexes for imparting UV protecting and antibacterial cellulose fabric: Experimental and computational investigations

In the search for ultraviolet radiation exposure protective textile to minimize risk factors for skin cancer, we synthesized a Schiff base ligand from the condensation reaction 2,4‐dihyroxybenzaldehyde with p‐amino aniline. Also, the Schiff base complexes with Fe (III), Mn (II), and Cr (III) were synthesized. The ligand and the complexes were characterized by ultraviolet (UV)‐visible, Fourier transform infrared spectroscopy, 1H 13C NMR, X‐ray diffraction, and elemental analysis. We treated cotton fabric (CF) with the complexes to achieve the conventional fabric materials with highly efficient and durable UV protection properties. The modified CF is also characterized via different techniques. UV protection properties of coated fabrics are investigated by measuring UV protection factor values. Excellent UV protection even after 10 washing cycles can be used in protective textiles. In contrast to fungal activity, modified CF demonstrated strong antibacterial activity. We used the density functional theory to compute the reactivity indices and the binding energy of the complexes with the cellulosic fiber. The theoretical results favor binding the Fe (III) complex with the cellulose fiber. Also, Fe (III) metal complexes gave the highest antibacterial and UV protection. The modified fabrics' antibacterial and excellent UV protection make the studied complexes potential candidates for applying UV protective (ultraviolet protection factor) textiles.

Retraction Note to: Schiff base transition metal complexes for Suzuki–Miyaura cross-coupling reaction

Retraction Note to: Schiff base transition metal complexes for Suzuki–Miyaura cross-coupling reaction

POTENTIALLY ACTIVE METAL OF COBALT, COPPER AND ZINC COMPLEXES DERIVED FROM SCHIFF BASE LIGAND OF 3-ETHOXY-2-HYDROXY-BENZALDEHYDE AND ANILINE FOR THEIR ANTICANCER ACTIVITY

New Schiff base transition metal complexes derived from 3-ethoxy-2-hydroxy-benzaldehyde and aniline were characterized by magnetic susceptibility measurements, molar conductance, MS, FT-IR, 1H-NMR, 13C-NMR, Absorbance and EPR spectra. The spectral evidences clearly showed that all the metal chelates distorted octahedral geometry except Zn(II) complex which exist square planar geometry. Electron Spin Resonance (ESR) spectrum of [CuL] complex was coinciding with proposed geometries and other reported complexes. All the synthesized compounds were studied for anticancer studies by MTT method using Hela cells. From anticancer activities, the observed IC50 values of synthesized complexes are significantly higher than standard Cis-platin. The cytotoxicity of the tested compounds against the Hela cell line pursued their order Co(II) > Cu(II) > Zn(II) > ligand. Among them, Co(II) complex showed higher cytotoxic activity than other complexes and Schiff base.

Novel thioether Schiff base transition metal complexes: Design, synthesis, characterization, molecular docking, computational, biological and catalytic studies

A series of novel copper(II), nickel(II), zinc(II) and cobalt(II) Schiff base metal complexes were synthesized by the reaction of 2‐(benzylthio) aniline with pyrrole‐2‐carboxaldehyde and characterized by FT‐IR, UV–visible, elemental analyses, 1H‐NMR, magnetic susceptibility and ESI‐MS. The Schiff base ligand posed as an NS‐bidentate ligand, confirming the synthesis of metal complexes with the suggested structure, according to the spectrum analysis data. All the complexes acquire square planar geometry. Furthermore, the DFT method was utilized to conduct computational analyses of metal complexes. The spectroscopic (UV–Vis and fluorescence) techniques were employed to probe the binding nature of calf thymus‐DNA binding to metal complexes. The metal complexes interact with DNA through intercalative mode, according to the spectroscopic titration data. The antioxidant properties of metal complexes were evaluated using their reducing ability and free radical scavenging activity of DPPH. The antioxidant property is high in isolated complexes. The in vitro anti‐inflammatory efficacy of all complexes has also been studied. All the metal complexes exhibited effective anti‐inflammatory activity and can be used as synthetic drugs. The synthesized copper(II) complex exhibits excellent catalytic activities for the transformation reaction of alcohol to aldehyde in the presence of hydrogen peroxide. The interaction of metal complexes with active sites of the B‐DNA (1‐BNA) and 6‐COX (COX 2) was studied using docking studies.

Synthesis, characterization, in vitro, in silico and in vivo investigations and biological assessment of Knoevenagel condensate β-diketone Schiff base transition metal complexes

A novel Schiff base ligand was synthesized by the Knoevenagel condensation of β-diketone (obtained from substituted Curcumin and Cuminaldehyde) and 4-amino antipyrine. Metal complexes were made from this Schiff base by reacting with metal salts such as Cu(II), Ni(II), Ru(III), VO(IV), and Ce(IV). Physicochemical approaches such as UV-Vis, FT-IR, NMR, EPR, and Mass spectroscopy were used to determine the geometry of the complexes. The thermodynamic stability and biological accessibility of the complexes were investigated using density functional theory (DFT) calculations at the B3LYP/6-31G(d) level. A molecular docking analysis was also performed on 1BNA receptor. Both the Schiff base ligand and metal complexes interacted well to this protein receptor. All metal complexes have a significant potential to bind to CT DNA via the intercalation mechanism. All the in vivo and in vitro screening studies showed that the complexes exhibit higher activities than the free Schiff base. Communicated by Ramaswamy H. Sarma

Investigation of new schiff base transition metal (II) complexes theoretical, antidiabetic and molecular docking studies

A new Schiff base ligand, 2-((Z)-(4-((furan-2-ylmethylene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylidene)amino)pyridine-3-ol have been synthesized by the condensation of 4-((furan-2-ylmethylene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with 2-amino-3-hydroxypyridine. Its divalent metal complexes of Cu(II), Ni(II), Co(II) and Zn(II) were also synthesized. The ligand and its metal complexes were characterized by Elemental analysis, UV-Visible, FT-IR, 1H NMR, 13C NMR, EPR, ESI-Mass spectra and thermal analysis (TGA & DTA). The consequences of antidiabetic studies showed that the complexes are potentially more active. The experimental and molecular docking studies revealed that the ligand and all the complexes can interact with a human pancreatic α-amylase (PDB: 1HNY) protein and they showed promising docking score value. The DFT calculations of quantum parameters and geometry optimization of ligand and complexes are done.

Synthesis, characterization, physicochemical studies, and antibacterial evaluation of surfactant-based Schiff base transition metal complexes

Synthesis, characterization, physicochemical studies, and antibacterial evaluation of surfactant-based Schiff base transition metal complexes

Synthesis, structural, pharmacological and molecular docking simulations studies of Schiff base transition metal complexes procured from acetylacetonyl-4-iminoantipyrine and tyrosine

Schiff base complexes of Cu(II), Ni(II), Co(II), VO(II) and Zn(II) ions have been synthesized by condensation of acetylaceto-4-iminoantipyrine and tyrosine. The structural characterization of compounds has been investigated using elemental analysis, molar conductance and magnetic susceptibility measurements, UV-Vis., FT-IR, ESI-mass, 1H-NMR, 13C-NMR, ESR spectroscopy, cyclic voltammetry, XRD and SEM techniques. The observed analytical data indicate that the metal chelates have the general formula of [ML] type. Powder XRD pattern of Schiff base and its complexes authenticate their crystalline nature. From SEM morphology studies, the reduction grain size of Schiff base in metal chelates was observed which is due to the chelation of the Schiff base. From the IR, electronic absorption spectra and magnetic measurement data, square planar geometry was proposed for the metal complexes except for the [VOL] complex which exhibits square pyramidal geometry. The X-band ESR spectra of [CuL] and [VOL] complexes in DMSO solution were recorded at 77 & 300 K and their spin Hamiltonian parameter values support the proposed geometry. The interactions of the [CuL] complex with CT-DNA were investigated by UV-Vis and absorption titrations. DNA binding interaction studies reveal the hydrophobic interaction between CT-DNA and complexes. Furthermore, analgesic, anti-inflammatory, CNS and antimicrobial studies of the Schiff base and its transition metal complexes were examined and resolved metal complexes have enhanced pharmacological and biological activity when compared to free Schiff base. Molecular docking studies of the complex with DNA and (PDB ID: 6COX) protein were investigated.

Ceftriaxone-based Schiff base transition metal(II) complexes. Synthesis, characterization, bacterial toxicity, and DFT calculations. Enhanced antibacterial activity of a novel Zn(II) complex against S. aureus and E. coli

From the reaction of ceftriaxone 1 antibiotic with 2,6-diaminopyridine 2 a ceftriaxone-based Schiff base (H2L,3) was obtained and its transition metal complexes were synthesized. Spectroscopic and physicochemical techniques, namely, UV–visible, FT-IR, 1H NMR, EPR, mass spectrometry, molar conductance, magnetic susceptibility and density functional theory (DFT) calculations, together with elemental and thermal analyses, were used to find out the binding mode and composition of these complexes. The ceftriaxone-based Schiff base 3 behaves as a monoanionic tridentate N,N,O ligand. Spectral and magnetic data suggest an octahedral geometry for all complexes and the general formulae [M(HL)(OAc)(H2O)2] (M(II) = Mn2+4, Co2+5, Ni2+6, Cu2+7, Zn2+8), are proposed for them. All compounds were screened for antibacterial activity using both the agar disc diffusion method and the minimal inhibitory concentration (MIC). It was found that complex 8 exhibited the most promising bactericidal activity against S. aureus (MIC = 0.0048 μmol/ml) and E. coli (MIC = 0.0024 μmol/ml). It is more active than the free ligand 1 (MIC = 0.0560 μmol/ml for S. aureus and 0.0140 μmol/ml for E. coli). These MIC results were compared with those obtained using similar zinc(II) Schiff base complexes, and with the values obtained using ceftriaxone conjugated with silver and gold nanoparticles (NPs), using earlier published data. Synthesized metal complexes exhibited LC50 values >1000 ppm indicating their nontoxicity against brine shrimp nauplii (Artemia Salina).

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL ACTIVITY STUDY OF SOME NEW METAL COMPLEXES WITH SCHIFF’S BASES DERIVED FROM [Ο-VANILLIN] WITH [2-AMINO-5-(2-HYDROXY-PHENYL)-1,3,4-THIADIAZOLE

Abstract This study involves the preparation of a new series of dinuclear complexes Cr(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base (H2L) derived from Vanillin with 2amino-5-(2-hydroxy-phenyl)-1,3,4-thiadiazole has been synthesized tetradentate Schiff base ligands were used for complexation upon two metal ions of Cr(III),Co(II), Ni(II), Cu(II) and Zn(II) as dineucler formula M2L2.4H2O and M2L2. These ligands can be characterization IR ,UV-Vis , Mass, 1H-NMR and elemental microanalysis. The Synthesized complexes were characterized by IR, spectroscopy, elemental microanalysis, electronic spectra, magnetic susceptibility conductive ,thermal Analysis (TGA) and atomic absorption on the basis of analytical data, the stoichiometry of metal to ligand in complexes and Schiff bases ligand. The Structures of complexes were proposed from the measurements. The bioactivity of the prepared complexes has been examined with antibacterial activity. Antimicrobial activities of the Schiff base ligand and their metal complexes reveal that the Schiff base transition metal complexes show significant activity against some fungi and bacteria.

Design, synthesis and biological evaluation of heterocyclic methyl substituted pyridine Schiff base transition metal complexes

In recent years heterocyclic Schiff base metal complexes attract more attention in biological application and also showing interesting co-ordination chemistry. In this research article a novel heterocyclic methyl-substituted pyridine Schiff base transition metal complexes of Fe(III), Co(III), Cu(II), and Ni(II) have been design and synthesized by reacting metal acetate or metal salts (FeCl3, CoOAc, CuOAc, NiOAc), with substituted heterocyclic ligand. All newly synthesized metalcomplexes were characterized by spectroscopic data and screened for elemental analysis, FT-IR, ESR, Magnetic susceptibility and TGA. The Electronic spectra and magnetic susceptibility measurements indicates that square planer and octahedral geometry of these complexes also suggest their structure in which (N, O) group acts as bidentate ligand. The thermal stability, decomposition rate and thermodynamic parameters of synthesized metal complexes were calculated by Freeman Carroll method. Also the biostatistical data of antimicrobial and anti-oxidant activities of synthesized metal complexes indicates moderate to good results.Graphic abstract

Synthesis, Characterization and Electrochemical Sensor Based Upon Novel Schiff Base Metal Complexes Derived from the Non-Steroidal Anti-inflammatory Drug, Flufenamic Acid for the Determination of Uric acid and their Biological Applications

The current trend in coordination chemistry is the design and synthesis of new Schiff base transition metal complexes for therapeutic, diagnostic, and catalytic applications. For decades, it has been observed that special attention is being paid to the chemistry of Schiff base metal complexes because of their wide range of applications. Therefore the present paper involves the synthesis of Schiff base ligand by altering the functional group of the drug, Flufenamic acid. From that Schiff base ligand, four complexes, i.e., Co(II), Cu(II), Ni(II), and Zn(II) have been prepared (SB metal complexes). The synthesized SB metal complexes have been characterized using several spectral and analytical techniques. All the metal complexes show non-electrolytic behavior suggested by molar conductance measurements. Spectral studies suggest that all four metal complexes exhibit octahedral geometry. The modified SB-Co complex/GCE showed a greater electro-catalytic activity and lower potential towards the oxidation of uric acid (UA). The response of UA was linear over the concentration ranging from CV is 0.5–1.8 μmol/L, sensitivity for 131.85 μAμM-1cm-2, and detection limit for 0.16 μM (S/N=3). The modified GCE showed very good sensitivity along with good repeatability and reproducibility for the determination of UA. The pure drug, Schiff base ligand, and metal complexes, were also screened for anti-inflammatory and antibacterial activities. The observed results prove that the metal complexes exhibit greater activity than that of the original drug.

Synthesis, Characterization and Biological Evaluation of Schiff Base Transition Metal Complexes Derived from 4-Nitrobenzene-1,2-diamine and 5-Chloroisatin

A series of transition metal complexes of the type [MLX2], where M = Mn(II), Fe(II), Co(II), Ni(II), X = Cl–/CH3COO– and L = Schiff base derived from 4-nitrobenzene-1,2-diamine and 5-chloroisatin have been synthesized and characterized by elemental analysis, molar conductance, IR, UV-visible, magnetic moments measurement, 1H & 13C NMR and mass spectral studies. On the basis of physico-chemical studies and spectral evaluation, an octahedral geometry have been proposed for all metal(II) complexes. The antimicrobial activity of ligand and its metal complexes have been additionally screened against bacteria and fungi. Metal(II) complexes show good activity as compared to ligand towards studied microorganisms and also metal complexes checked for their catalytic properties for benzoylation of phenol.

Synthesis, Characterization and DNA Binding Studies of N,N′-bis(2-Hydroxy-5-methylbenzylidene)- 2-hydroxy-propane-1,3-diamine Copper(II) and Nickel(II) Complexes

Two new Schiff base transition metal complexes [Cu(HL)]2.CH3CH2OH (1) and [Ni(HL)] (2) (L = N,N′-bis(2-hydroxy-5-methyl-benzylidene)-2-hydroxy-propane-1,3-diamine) were synthesized and characterized by different physico-chemical and spectroscopic techniques. Structure of complex 1 was determined by single crystal X-ray diffractometer. Both the complexes have distorted square planar geometry. The DNA binding study of two complexes was performed via electronic absorption, cyclic voltammetry, photoluminescence, and viscosity methods and found to be intercalative mode of binding.

Synthesis, characterization and biological evaluation of novel 2,2′-((1,2-diphenylethane-1,2-diylidene)bis(azanylylidene))bis(pyridin-3-ol)and metal complexes: molecular docking and in silico ADMET profile

A novel series of bio vital Schiff base ligand and transition metal complexes was prepared from benzil, 2-amino-3-hydroxy pyridine and metal chlorides. The synthesized compounds were characterized by physicochemical measurements like elemental analysis, magnetic susceptibility, molar conductance and multispectral analysis like Fourier transform, electronic absorption, nuclear magnetic resonance, electron paramagnetic resonance, ESI-mass spectroscopy, XRD and scanning electron microscopy. Based on the spectral results, the synthesized compounds are in crystalline nature and copper complex has square planar geometry. Conversely, cobalt, nickel and zinc complexes have tetrahedral geometry. Furthermore, the biological potential of the synthesized compounds is analysed by DNA binding and cleavage analysis and antimicrobial, anticancer, apoptosis and antioxidant inspections. The DNA binding analysis was performed using UV absorption titration and hydrodynamic experiments, which unveiled that the prepared compounds could be interconnected with calf thymus DNA by the way of intercalative mode. The mode of intercalation is further supported by docking investigations with nucleic acid and Bowman-Birk inhibitor. The DNA cleaving analysis implied that Cu(II) complex has eminent cleaving ability to split up the pUC18 DNA with an oxidising agent. Additionally, the anti-pathogenic screening studies explained that the complexes have antimicrobial skill against selected microbes. The anti-carcinogenic talent of the compounds is scrutinized on human cancer cell lines, which revealed that the prepared compounds possess good anticancer proficiency. During Hoechst staining analysis, the synthesized compounds have undergone the morphological moderations and succeeding cell death. The free radical scavenging investigations display that the metal complexes hold the suited talent to hunt the OH radical effectively. The prediction of in silico ADMET belongings found out that synthesized compounds acquire substantial drug-likeness characters based on Lipinski’s rules.

RETRACTED ARTICLE: Three novel Schiff base transition metal(II) complexes induce gastric cancer cell death through ROS-mediated apoptotic pathway

We, the Editors and Publisher of the Journal of Coordination Chemistry, have retracted the following article: Xiu-Heng Qi, Zhen-Ming Wu, Shuai-Bing Wang, Bao-Xin Wang, Ling-Ling Wang, Haiyan Li & Qian Guo (2019) Three novel Schiff base transition metal(II) complexes induce gastric cancer cell death through ROS-mediated apoptotic pathway, Journal of Coordination Chemistry; 2019, VOL. 72, NO. 14, 2310–2325. DOI: 10.1080/00958972.2019.1647535 Since publication, concerns have been raised about the integrity of the data in the article. When approached for an explanation, the authors have been unable to address the concerns raised and have not been able to provide sufficient supporting information. As verifying the validity of published work is core to the integrity of the scholarly record, we are therefore retracting the article. The corresponding author listed in this publication has been informed. The authors do not agree with the retraction. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.