Schiff Base Metal Research Articles

Schiff base metal complexes: Synthesis, optoelectronic, biological studies, fabrication of zinc oxide nanoparticles and its photocatalytic activity

A Schiff base ligand from amino acid (L-Histidine) and salicylaldehyde (L1), 1,10 phenanthroline (L2) and its transition metal complexes of general formula [ML1L2] (where M = Co(II), Cu(II), Zn(II), and Cd(II)) have been synthesized, characterized and tested for in vitro antimicrobial activity, antioxidant scavenging assay, DNA binding and used as a precursor for the synthesis of zinc oxide nanoparticles. TGA-DTA analysis was used to investigate the thermal stability of the complexes. The redox characteristics of the complexes were examined using cyclic voltammetry. The synthesized complexes exhibited excellent antioxidant properties both by DPPH and hydrogen peroxide assays. Cd(II) complex shows the maximum zone of inhibition values for S. aureus (20 mm) and M. ellipsoideus (21 mm). Among the synthesized complexes, Cd(II) complex showed the highest antimicrobial and very good antioxidant properties. Zn(II) Schiff base complex has been utilized as a precursor to synthesize ZnO nanoparticles by the thermal decomposition process. Powder X-ray diffraction (PXRD), Scanning Electron Microscopy (SEM), Transmission Electron microscopy (TEM), FT-IR spectroscopy, and UV–Vis spectroscopy have been used to analyze ZnO nanoparticles and ZnO used as a photocatalytic material to degrade organic dyes namely methylene blue, methyl orange, rhodamine B, and crystal violet under ultraviolet light for 1 h. The results showed the maximum degradation of 98.7% against methylene blue.

Computational studies, cytotoxicity, DNA interactions of bioactive novel 2-methoxy 5-trifluoromethyl benzenamine Schiff base metal complexes

Two novel Schiff base ligands (HL1), (HL2) and their metal(II) complexes [Co(HL1)2(H2O)2]-A; [Ni(HL1)2]-B; [Cu(HL1)2]-C; [Co(HL2)2(H2O)2]-D; [Ni(HL2)2]-E; [Cu(HL2)2]-F have been characterized by various techniques (NMR, FTIR, ESI mass, UV-Visible, ESR, TGA) and confirmed that Ni (II), Cu(II) complexes exhibit square planar geometry whereas Co(II) complexes exhibit octahedral geometry. Interaction experiments involving DNA binding and cleavage studies have revealed that the mode of binding is intercalative and complexes effectively cleave supercoiled DNA. Pathological tests of all compounds against microbial strains in vitro showed that all complexes are more potent than free ligands and Cu(II) complexes are more potent than other complexes. Higher antioxidant activity (by DPPH method) was found by Cu(II) complexes. In addition, synthesized compounds were evaluated for their in-vitro cytotoxic potential against human breast cancer cell (MCF-7) and oral cancer cell (KB3) using cis-platin as a standard drug by MTT assay and found complexes are more potent than free ligands.

Synthesized and hypothesized schiff base ligand and its metal(II) complexes DNA binding mode

ABSTRACT. Metal complexes play an important role in agriculture, pharmacology, medicine, and industrial chemistry. Schiff base metal compounds are the fusion products of propene and aldehydes, require a metal surrounded by an ion or cluster of molecules to form. Metal complexes of Co(II), Ni(II), Cu(II), and Zn(II) have also been created. Elemental analysis is used to analyses the structure and related compounds of the produced Schiff base ligand. According to deoxyribose nucleic acid (DNA) binding tests, Schiff base metal(II) complexes attach to DNA in an intercalative form with weak covalent connections. The predicted DNA binding mode supports an increase in the complexes' binding activity in the presence of newly generated ligand. The cleavage activities of the DNA were recorded using gel-electrophoresis in the presence and absence of the complexes. The findings of the cleavage experiment show that all of the produced chelates can successfully cut DNA.
 
 KEY WORDS: Schiff base ligand, DNA, Metal(II) complex, Hetero-ligand cobalt(II), Aldehydes
 Bull. Chem. Soc. Ethiop. 2023, 37(5), 1133-1139. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i5.6

Design, Structural characterization, Molecular docking, and biomedical applications of hydrazone -based Schiff base metal complexes

Design, Structural characterization, Molecular docking, and biomedical applications of hydrazone -based Schiff base metal complexes

Newly synthesised Schiff base metal complexes, characterisation, and contribution as enhancers of colon cancer cell apoptosis by overexpression of P53 protein

Fluoroquinolones emerged as one of potent therapeutic agents, targeting DNA‐signalling pathways. Thus, efforts were spent to create novel quinolones for optimizing their antimicrobial and anticancer properties. Therefore, the new compoundN,N′‐phenylene (bis1‐cyclopropyl‐7‐(4‐ethylpiperazin‐1‐yl)‐6‐fluoro‐1,4‐dihydroquinoline‐3‐carboxylic acid) (H2Enro‐o‐phdn) in addition to its related chelates‐contained metals were synthesised and described by spectroscopic, physical methods and thermal analyses. The reaction between H2Enro‐o‐phdn and trivalent La(III), Y(III), and Fe(III) and tetravalent Zr(IV) chloride with molar ratio 1:1 (M:H2Enro‐o‐phdn) yielded the production of chelates. The infrared results elucidate the binding mode of H2Enro‐o‐phdn by means of azomethine nitrogen and carboxylato oxygen atoms as tetradentate. The thermal analyses assured the proposed formula as well as existence of coordinated and latticed H2O molecules. Kinetic parameters for investigated metal complexes were quantified utilisation Horowitz–Metzger in addition to Coats–Redfern methods. Regarding antibacterial efficacy, Y(III) and Fe(III) complexes showed a robust inhibitory activity towards negative‐gram stained (Escherichia coliandSalmonella typhi) and positive‐Gram stained (Staphylococcus aureusand “spore‐forming”Bacillus cereus) strains. Then, we further tested the cytotoxicity of the complexes against the survival of colon‐cancer cells line (CT26). In this regard, in the descending order, Fe(III) > Zr(IV) > La(III) complexes possessed a powerful antitumour activity with IC50values 6.38, 5.36, and 4.03 μM, respectively, compared with the anticancer drug‐reference cisplatin (16.77 μM). To understand the precise mechanism behind the tumour cell death, Western‐blotting analysis was conducted, to monitor the changes in levels of pro‐apoptotic “P53” protein after drug‐treatment. Results indicated that H2Enro‐o‐phdn with higher covalency metals, like La(III) and Zr(IV) complexes, had the highest upregulation of P53 expression in a threefold to fourfold compared cisplatin, paving the way for a novel P53‐based colon‐cancer therapies.

Experimental and Insilico Evaluations of Transition Metal Complexes with L-Histidine (N, N Donor) Schiff Base Ligand and Its Biological Applications in Ovarian and Melanoma Cancer Cell Lines

Schiff base metal complexes are essential in modern coordination chemistry. It owns modern structural features and finds several uses in various fields, including pharmaceuticals, agriculture, dyeing, polymer science, food packaging, O2 detection, various biological systems, catalysis, and birth control. The Chemistry of Schiff base ligands and their metal complex increased, encompassing a wide range of organometallic compounds and bio-inorganic chemistry. Schiff bases belong to the class of organic compounds regarded as particularly significant. They have been investigated extensively in the past few years and have attracted much attention due to their appealing chemical and physical features. They are versatile and have a broader range of applications, such as anti-cancer, anti-fungal, anti-microbial, antiulcer, anti-tumor, anti-diabetic, herbicidal, anti-proliferative, and anti-inflammatory actions. The aim and objective of our research are to synthesize a series of five new Zn (II), Ni (II), Cu (II), Mn (II), and Co (III) of bis-3-(4.5-Dihydro-3 H-imidazol-4-yl)-2-[(4-methoxy-benzylidine)-amino]- propionic acid Schiff base metal complexes and to characterize those complexes by elemental analysis, UV-Visible, FT- IR, and Mass spectral studies. Bis-3-(4.5-Dihydro-3 H-imidazol-4-yl)-2-[(4-methoxy-benzylidine)-amino]-propionic acid ligand coordinates to metal ions as bidentate N and O donors. Biological studies of the synthesized Schiff base complex have also been investigated by anti-microbial, radical scavenging, docking study, anticancer analysis, and cytotoxic studies. Based on the analytical and spectral results, tetrahedral geometry has been tentatively proposed for all complexes except that of cobalt. The antioxidant studies of the Schiff base ligand and Schiff base complexes exhibit significant free radical scavenging activity against DPPH. Invitro cytotoxic activity of the Schiff complexes was evaluated against the over3 (ovarian) and melanoma cell lines (MCF14). The docking studies have been carried out using BSA protein and DNA biomolecules with synthesized metal complexes. Antimicrobial studies demonstrated the effectiveness against gram-positive and gram-negative bacteria.

Glycopeptide‐Based Multifunctional Hydrogels Promote Diabetic Wound Healing through pH Regulation of Microenvironment

AbstractExcessive inflammation, bacterial infection, and blocked angiogenesis make diabetic wound healing challenging. Multifunctional wound dressings have several advantages in diabetic wound healing. In addition, the pH regulation of the microenvironment is shown to be a key factor that promotes skin regeneration through cellular immune regulation. However, few reports have focused on the development of functional dressings with the ability to regulate the pH microenvironment and promote diabetic wound healing. This study presents a novel approach for regulating the pH microenvironment of diabetic wound sites using a glycopeptide‐based hydrogel consisting of modified hyaluronic acid and poly(6‐aminocaproic acid). This hydrogel forms a network through Schiff base interactions and metal complexation, which suppresses inflammation and accelerates angiogenesis during wound healing. Hydrogels not only have adequate mechanical properties and self‐healing ability but can also support tissue adhesion. They can also promote the secretion of inducible cAMP early repressor, which promotes the polarization of macrophages toward the M2 type. The in vivo results confirm that hydrogel promotes diabetic wound repair and skin regeneration by exerting rapid anti‐inflammatory effects and promoting angiogenesis. Therefore, this hydrogel system represents an effective strategy for treating diabetic wounds.

Microwave assisted Schiff base metal complexes as potential anticancer and antimicrobial agents: A critical review

Schiff bases are organic compounds which contain azomethine group (-C=N-) by reacting primary amines and carbonyl compounds. The presence of an azomethine group in the Schiff base facilitates coordination with transition metal ions. The term Schiff base is normally applied to these compounds when they are being used as ligands to form coordination complexes with metal ions. Such complexes occur naturally, but the majority of Schiff bases are artificial and are used to form many important catalysts. Schiff base metal complexes prepared using microwave irradiation have gained more attention because of their excellent strategy in generating quick and stable products in higher yields by improving the speed of reaction with lesser energy and exhibits various biological activities including antifungal, antibacterial, anti-tubercular, antiviral, antimalarial, anti-diabetic, anticancer, antioxidant, antidiuretic, anti-inflammatory, antipyretic and anti-HIV agents. Apart from biological applications, they are also used as a catalyst in Aldol reactions, polymerization reactions, oxidation reactions and other chemical reactions. Imine-ligand containing transition metal complexes including copper, zinc and cadmium, have proven to be effective starting points for the synthesis of metal or metal chalcogenide nanoparticles. In this review, various metal complexes derived from Schiff bases synthesised using microwave approaches are discussed along with their antibacterial, antifungal and anticancer activities.

Investigation of microwave assisted synthesis of Schiff Base derived Metal-Chelates by liquid invert sugar containing D-Glucose

The ethanol-soluble (6E,6'E)-6,6'-(1,2-phenylenebis(azan-1-yl-1-ylidene))dihexane-1,2,3,4,5-pentaol (LISPDA) and (E)-6-(2-hydroxyphenylimino)hexane-1,2,3,4,5-pentaol (LISAP) were investigated in this study. Condensation of 1,2-phenylenediamine and 2-aminophenol with 2,3,4,5,6-pentahydroxyhexanal (GL) in the presence of weak acid as a catalyst under mono-mode microwave heating yielded the glucose-Schiff base product. A one-pot microwave-assisted reaction in a short reaction time was required to complete the imine condensation reaction with 90% yield and no byproducts. The molecular structures of these were discovered to be in an extended conformation, with the aromatic moiety coplanar with that of the imine bond and the imine bond exhibiting trans-geometry. Schiff base metal complexes were successfully synthesized by combining 1,2-phenylenediamine and 2-aminophenol with D-glucose and Co(II), Ni(II), and Cu(II). Elemental analysis, magnetic susceptibility, thermal analysis, and electronic and infrared spectral studies were used to determine the structural assessment of ML2 complexes.

Synthesis, DFT calculations, α‐glucosidase inhibitor activity, and docking studies on Schiff base metal complexes containing isothiocyanate

Diabetes is one of the fastest growing global health crises of the 21st century. One of the current therapeutic approaches used in the treatment of diabetes involves the suppression of carbohydrate hydrolyzing enzymes such as α‐glucosidase. In this context, α‐glucosidase inhibitors are important in the treatment and prevention of diabetes. For this reason, new Schiff base complexes including isothiocyanate {[Cd(L1)2(NCS)2], (1), [Zn(L1)2(NCS)2], (2), [Cu(L1)2(NCS)2], (3), [Ag(L1)(NCS)2], (4), [Hg(L1)2(NCS)Cl], (5); L1: N‐(pyridin‐2‐ylmethylene)methanamine} were synthesized to investigate α‐glucosidase inhibitor potentials. The IC50 values of complexes 1–5 were found at 0.2376 ± 0.82 and 251.403 ± 2.54‐μM range. Among these complexes, complex 5 has the highest α‐glucosidase inhibitor property. The spectral investigations for the complexes 1/2–5 characterized by XRD/LC‐HRMS were performed by UV–Vis and FT–IR spectra. Furthermore, the TD‐DFT/DFT calculations were fulfilled by using CAM‐B3LYP and ωB97XD/6–311+G(d,p)//LanL2DZ levels to obtain optimum complex structures, spectral, linear and nonlinear optical properties for 1–5. According to obtained theoretical nonlinear optical results, complex 3 is a strong indicator in terms of microscopic nonlinear optical (NLO) properties. The docking studies of these complexes were examined to display the target protein interactions with these complexes.

One-pot synthesis, characterization, photocatalytic activity and biological studies of Co(II), Ni(II) and Cu(II) complexes of a tetraazamacrocyclic Schiff base

Template condensation between pentane-1,5-dial and triethylenetetramine in the presence of divalent metal salts in methanolic solution resulted in mononuclear 15-membered tetraazamacrocyclic Schiff base metal complexes, [M(C11H22N4)X2], where M = Co(II), Ni(II) and Cu(II), X = Cl− and C11H22N4 is the tetradentate macrocyclic ligand. The bonding and overall geometry of the complexes are inferred through elemental analysis, FT-IR, UV–vis, 1H/13C NMR, ESI-mass, molar conductance, magnetic susceptibility and TG measurements. On the basis of the absorption bands in UV–vis spectra and magnetic moment analyses, a six-coordinate octahedral geometry is proposed for all the metal complexes. The formulation of the metal chelates is compatible with the thermal decomposition profiles. Photocatalytic efficiency of the macrocyclic Ni(II) complex was studied using solar water-splitting. The in vitro antimicrobial activity of metal complexes has been tested against certain bacterial and fungal species. The scavenging ability of DPPH free radicals was used to test the antioxidant activity of the complexes. In addition, MTT assay was used to assess the cytotoxicity of Cu(II) chloro complex against L929 mouse fibroblast cell lines.

Synthetic methodologies and pharmacological applications of sulphonamide containing Schiff bases and their metal complexes: A comprehensive review

Schiff bases are useful chemical compounds with a wide range of applications. The Schiff bases are synthesized via the condensation reaction between carbonyl compounds (aldehydes or ketones) and compounds having an amine group and the Schiff base is characterised by an imine or azomethine (-C=N-) group. These compounds are extensively used as ligands to form coordination complexes with metal ions and are widely utilized in the treatment of various ailments. Sulphonamides are biologically significant class of drug-like chemical derivatives due to their good oral absorption and urine excretion. Sulphonamides are widely used as antimicrobial, anti-inflammatory, anticancer and antiviral drugs in addition to acting as powerful Carbonic anhydrase hCA inhibitors, HIV protease inhibitors, anti-obesity and anti-thyroid agents because of their less poisonous, more reactive and cost-effective nature. Sulphonamide-based Schiff bases and their metal chelates have attracted the focus of researchers due to their broad range of pharmacological characteristics. In this review, various pharmacological uses of Schiff base metal complexes generated from sulphonamide derivatives are discussed.

Solvent-Free Coupling Reaction of Carbon Dioxide and Epoxides Catalyzed by Quaternary Ammonium Functionalized Schiff Base Metal Complexes under Mild Conditions.

A series of bifunctional Schiff base metal catalysts (Zn-NPClR, Zn-NPXH, and M-NPClH) with two quaternary ammonium groups were prepared for carbon dioxide (CO2) and epoxide coupling reactions. The effects of the reaction variables on the catalytic activity were systematically investigated, and the optimal reaction conditions (120 °C, 1 MPa CO2, 3 h) were screened. The performances of different metal-centered catalysts were evaluated, and Co-NPClH showed excellent activity. This kind of bifunctional catalyst has a wide range of substrate applicability, excellent stability, and can be reused for more than five runs. A relatively high TOF could reach up to 1416 h-1 with Zn-NPClH as catalyst by adjusting reaction factors. In addition, the kinetic study of the coupling reaction catalyzed by three catalysts (Zn, Co, and Ni) was carried out to obtain the activation energy (Ea) for the formation of cyclic carbonates. Finally, a possible mechanism for this cyclization reaction was proposed.

Synthesis of novel Schiff base metal complexes and their spectroscopic characterization, biological activity and molecular docking investigation

In this study, Schiff base ligand namely N'-(3,4,5-trimethoxybenzylidene) benzohydrazide (I) and its metal complexes such as Cu(II) and La(III) (II and III) have been prepared. An elemental analysis, powder X-ray diffraction, FTIR, 1H NMR spectra, and thermal studies were used to characterize the Schiff base ligand and its metal complexes. According to infrared and 1H NMR analysis the ligand behaves as isobidentate. The electronic spectra reveals that charge transfer transitions are most centered on the ligand. An interesting fragmentation patterns was reported from thermal, biological activity and docking studies. Anti-bacterial studies were performed at least three times under identical conditions, these was estimated by measuring the zone of inhibition (mm) of the ligand and metal complexes against Escherichia coli, Bacillus subtilis, and Enterococcus faecalis strains of gram +ve and gram -ve bacteria. Molecular docking analysis was identified the molecular distance, energy account, and position of links contribution to the interaction between these complexes. These interactions demonstrate a strong interaction between the protein receptor molecule and the produced ligand and its La(III) complex, which were favorably affects the free binding energy. According to the values of interaction energies, the Cu(II) complex exhibited a significantly more stable interaction and a lower binding energy.

H2O2 activation over Cu-Schiff bases nanozyme for the removal of amlodipine: Kinetics, mechanism and toxicity evaluation

Artificial nanozyme is a promising alternative approach to replace natural enzyme and promote their industrialization. For designing artificial enzymes, the structure of the ligand is one of the important factors which needs to be considered. Schiff bases as special donor ligands could effectively stabilize active metal ions, endowing them playing important roles in the field of artificial enzymes. Herein, we focused on constructing a Schiff base metal complex with peroxidase-like activities to achieve efficient activation of hydrogen peroxide (H2O2) for the removal of amlodipine (AML). Polydopamine (PDA) and 3, 5-dibromosalicylaldehyde (DBSA) were used as raw materials to synthesize the Schiff base (DPDA), and Cu2+ is used for the coordination reaction to synthesize the Schiff base metal complex (Cu@SB). Our results demonstrated the prepared Cu@SB effectively activated H2O2 to degrade AML, and the removal of AML followed a pseudo first-order kinetic model. Electron paramagnetic resonance (EPR) tests and quenching tests showed •OH and 1O2 were responsible for removing AML. X-ray photoelectron spectroscopy (XPS) analysis implied the redox reaction of Cu(I)/Cu(II) participated in the catalytic process. Three major transformation pathways including dehydrogenation, oxidative deamination and hydroxylation were proposed based on density functional theory (DFT) calculations and LC-MS/MS analysis. Moreover, it was discovered that the toxicities of most intermediates were lower than AML. Overall, this study provides new insights into constructing peroxidase-like catalysts used for the efficient activation of H2O2 to remove emerging organic pollutants in water, broadening the application of Schiff bases in wastewater treatment.

New Dual Inhibitors of SARS-CoV-2 Based on Metal Complexes with Schiff-Base 4-Chloro-3-Methyl Phenyl Hydrazine: Synthesis, DFT, Antibacterial Properties and Molecular Docking Studies

This paper explores a dual inhibition of main protease (Mpro) and nonstructural protein 10/nonstructural protein 16 (NSP16) methyltransferase complex as the key targets for COVID-19 therapy. These are based on the new Schiff-base ligand that was obtained from the condensation of (4-chloro-3-methyl phenyl) hydrazine with 2-pyridine-carboxaldehyde and its novel Schiff-base metal complexes. These include Ni(II), Pd(II), Pt(II), Zn(II), and Hg(II). The newly synthesized compounds have been characterized using FT-IR, 1H NMR, 13C NMR, and elemental analysis. The results suggested that the Schiff-base ligand is coordinated as a bidentate ligand through the nitrogen atoms of the azomethine group and pyridyl ring. In addition, the biological activity of the prepared complexes was examined against Pseudomonas aeruginosa and Staphylococcus aureus, and the results showed that the Zn(II) complex has the highest activity compared with other compounds. The active sites were found by looking at the molecular electrostatic potential (MEP) maps of the above ligands and complexes. The activity of the compound and its Ni(II) and Zn(II) complexes against Mpro and NSP10/ NSP16 was investigated using a molecular docking approach. They showed excellent binding energies ranging from −5.9 to −7.2 kcal/mol and −5.8 to −7.2 for Mpro and NSP16, respectively. All conformers of the metal complexes were docked with the active site of the NSP16 receptor, showing a binding affinity of 100%. According to our knowledge, this was the first report of these metal complexes as dual inhibitors for Mpro and NSP16 of SARS-CoV-2.

Thermal Observation of Zr (IV) and UO2 (VI) Complexes Derived from Thiazole Schiff Base

The innovative newly thiazole Schiff base have been synthesized 2-hydroxy-5-chloro acetophenone and 4-(p-hydroxyphenyl)-2-aminothiazole by microwave irradiation method. The metal complexes were obtained as a result of interaction of Schiff base ligand and metal ions Zr (IV) and UO2(VI). The complexes have been characterized on the basis of elemental analysis, infrared, molar conductance, magnetic Susceptibilities, and theromogravimetric analysis. The kinetic analysis of the thermogravimetric data was performed by using Broido, Horowitz-Metzger and Freeman-Carroll method, which confirm first order kinetics and kinetic compensation effect.

Synthesis, Spectral Characterization and Antimicrobial Evaluation of 1- Hydroxy-2-acetonaphthone Schiff Base and their Fe(II), Mn(II) Metal Complexes

Herein, we are reporting synthesis, characterization and antimicrobial activity of two novel Fe(II) and Mn(II) Schiff base metal complexes. These metal complexes were characterized by UV-Vis., FT-IR, NMR, LCMS, ESR and powder X- ray diffraction study. UV-Vis spectra resulted in more than 400 nm transition peak that confirms formation of metal ligand charge transfer. FT-IR confirms the formation of unsymmetrical Schiff base ligand and its complex obtained by using naphthol -OH and azomethine -C=N- group. 1H-NMR spectral data confirms the formation of Schiff base ligand and its complexes. From the XRD study, we approve that the formed Fe(II) and Mn(II)complexes show orthorombic crystal system. ESR spectra of Mn(II) complex suggested an octahedral geometrical arrangement surrounding to the central metal ion. Antimicrobial activity of Schiff base and their metal complexes was observed for two gram negative E. coli, P. aeruginosa and two-gram positive S. aureus and B. subtilis bacterial strains. Antifungal activity of Schiff base and their metal complexes was also observed for two fungi C. albicans and A. niger. It was observed that the formed complexes exhibit higher activity than the compared Schiff base.

Novel Gold(III), Palladium(II) and Copper(II) Schiff Base Complexes Derived from 1-Hydroxy-2-acetonaphthone and Phenylethyl Amine: Synthesis, Characterization and Biological Studies

In this work, a novel Schiff base from 1-hydroxy-2-acetonaphthone and phenyl ethylamine and its metal complexes were synthesized and characterized using UV-visible, FT-IR, 1H and 13C NMR, SC-XRD, LCMS, TGA-DSC and powder X-ray diffraction. The IR data indicated that the ligand was coordinated via bidentate bonding through the oxygen atom of naphthone and nitrogen atom of azomethine unit. The TGA-DSC analysis of Au(III), Pd(II), and Cu(II) revealed the presence of coordinated water molecules. According to powder X-ray diffraction data, the Schiff base ligand exhibits a tetragonal crystal structure, Au(III) complex has a cubic crystal structure, while Pd(II) and Cu(II) complexes have monoclinic crystal structures. The synthesized metal complexes were examined for their in vitro antibacterial bioactivity against the Gram-negative bacteria E. coli, P. aeruginosa and Gram-positive S. aureus, B. subtilis as well as their in vitro antifungal activity against the two fungus C. albicans and A. niger. According to the biological findings, the synthesized metal complexes exhibited better antimicrobial activities compared to the Schiff base ligand. Similar, outcomes were followed in the antioxidant activity analysis, where the synthesized Schiff base metal complexes had DPPH radical scavenging activity.

Pharmacological aspects of Co(II), Ni(II) and Cu(II) schiff base complexes: An insight

Schiff bases are versatile chemical compounds that are frequently utilized and manufactured by reacting various amines with carbonyl compounds (aldehydes/ketones), resulting in the formation of the azomethine/imine (–CN–) group by condensation reaction. Medical science is driven to generate novel drugs with revolutionary bioactivities and functionalities to cure diseases that are rapidly evolving. Schiff base (SB) is a dynamic pharmacophore that, through chelation, can create complexes with metals of various oxidation states. SB metal complexes have already been recognized as an effective branch of investigation in coordination science. In the recent years, scientists have paid close attention to SBs and the metal complexes owing to versatile potential in the pharmaceutics sector, such as antifungal, antibacterial, antiviral and antimalarial, anti-HIV, anti-cancer, anti-tuberculosis, and many others. These compounds have also been identified as potent oxidants, with applications in sensing and nanotechnology. The ligand environment, metal ion complexation, and lipophilic nature have an impact on the biological activity of transition metal complexes. SB metal complexes are the attractive targets for the development of broad-spectrum medicines due to their combination of pharmacological properties. The review focuses on the synthesis, spectroscopic characterization and in-vitro biomedical applications (antimicrobial, anticancer, antitumor, DNA binding and cleavage, antioxidant) of SBs as well as their Co(II), Ni(II) and Cu(II) transition metal complexes.