View of MIXED-LIGAND NICKEL(II) COMPLEXES WITH SCHIFF BASES AND THIAZOLE DERIVATIVES: SYNTHESIS, CHARACTERIZATION, AND ANTIMICROBIAL STUDIES

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VOLUME: 09, Special Issue 07, (IC-RSDSHPMTM-2022) Paper id-IJIERM-IX-VII, December 54 2022

MIXED-LIGAND NICKEL(II) COMPLEXES WITH SCHIFF BASES AND THIAZOLE DERIVATIVES: SYNTHESIS, CHARACTERIZATION, AND ANTIMICROBIAL STUDIES

Km Chandni Singh Chemistry, Glocal University Guide Name- Dr. Satyavir Singh (Professor) Glocal School of Science

Abstract- The paper describes the synthesis, characterization, and antimicrobial studies of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives. The complexes were synthesized using a two-step process involving the formation of Schiff bases by the condensation of aromatic aldehydes and amines, followed by the reaction of the Schiff bases with nickel(II) chloride and thiazole derivatives. The resulting complexes were characterized using various techniques such as elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and magnetic susceptibility measurements. The structures of the complexes were also determined using single-crystal X-ray diffraction analysis. The antimicrobial activities of the complexes were evaluated against various bacteria and fungi. The results showed that the complexes exhibited good to moderate antimicrobial activities against the tested microorganisms. Overall, the study demonstrates the potential of mixed-ligand nickel(II) complexes as antimicrobial agents and highlights the importance of ligand design in the development of effective metal-based antimicrobial agents

Keywords: Mixed-ligand complexes, nickel(II), Schiff bases, thiazole derivatives, synthesis, characterization, antimicrobial activity, bacteria, fungi, ligand design.

1 INTRODUCTION

Metal-based complexes have gained significant attention in recent years due to their diverse applications in various fields, including catalysis, medicine, and materials science. Among metal-based complexes, nickel(II) complexes have received particular interest due to their unique electronic and structural properties. Schiff bases and thiazole derivatives are two types of ligands that have been extensively studied for their potential as building blocks for metal-based complexes. Schiff bases are formed by the condensation of an aldehyde and an amine, and they have been shown to possess various biological and pharmacological activities. Thiazole derivatives, on the other hand, are heterocyclic compounds that have been widely used as building blocks for drug development due to their diverse biological activities.

Mixed-ligand complexes, which contain two or more different types of ligands, have been shown to exhibit enhanced properties compared to their mononuclear counterparts. In particular, mixed-ligand nickel(II) complexes have been shown to possess unique structural and electronic properties that make them attractive for various applications. In this context, the present study aims to synthesize and characterize mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives and evaluate their antimicrobial activities against various bacteria and fungi. This study could provide insights into the design of effective metal-based antimicrobial agents and contribute to the development of new therapeutic strategies for infectious diseases.

Nickel(II) complexes are known to exhibit a wide range of biological activities, including antimicrobial, antitumor, and antiviral properties. These properties arise from the ability of nickel(II) ions to coordinate with different types of ligands and interact with various biological targets. Schiff bases, which are derived from the condensation of an aldehyde and an amine, have been shown to possess various biological and pharmacological activities, including antimicrobial, antitumor, and antiviral properties.

Thiazole derivatives, on the other hand, are heterocyclic compounds that have been widely used as building blocks for drug development due to their diverse biological activities, such as antimicrobial, antitumor, and anti-inflammatory properties.

Mixed-ligand complexes, which contain two or more different types of ligands, have been shown to exhibit enhanced properties compared to their mononuclear counterparts. In particular, mixed-ligand nickel(II) complexes have been shown to possess unique structural and electronic properties that make them attractive for various applications. The use of

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mixed-ligand complexes allows for the incorporation of different ligands with complementary properties, resulting in improved stability, solubility, and biological activity.

Moreover, the choice of ligands can be tailored to achieve specific properties and target biological systems.

The development of effective antimicrobial agents is a major challenge due to the emergence of drug-resistant strains of bacteria and fungi. Metal-based complexes have been proposed as potential alternatives to conventional antibiotics due to their unique modes of action and ability to overcome antibiotic resistance. Nickel(II) complexes, in particular, have shown promise as antimicrobial agents due to their ability to interact with various biological targets, including DNA, enzymes, and membranes. The incorporation of Schiff bases and thiazole derivatives in mixed-ligand nickel(II) complexes could enhance their antimicrobial activity by targeting multiple biological systems and overcoming resistance mechanisms.

The synthesis of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives typically involves a two-step process. In the first step, Schiff bases are synthesized by the condensation of an aldehyde and an amine in the presence of a suitable catalyst. The resulting Schiff base ligands are then used to form mixed-ligand complexes with nickel(II) chloride and thiazole derivatives in the second step. The resulting complexes can be characterized using various techniques such as elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and magnetic susceptibility measurements. The structures of the complexes can also be determined using single-crystal X-ray diffraction analysis, which provides detailed information on the molecular geometry and bonding interactions.

The antimicrobial activity of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives can be evaluated against various bacteria and fungi using standard methods such as the disc diffusion assay and the broth microdilution method. The results of these studies can provide insights into the potential of these complexes as antimicrobial agents and their mechanism of action. The use of mixed-ligand complexes could enhance the antimicrobial activity of the complexes by targeting multiple biological systems and overcoming resistance mechanisms.

Apart from their potential as antimicrobial agents, mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives have been studied for their potential applications in other fields. For example, nickel(II) complexes have been proposed as catalysts for various reactions due to their ability to coordinate with different types of ligands and activate substrates. The use of mixed-ligand complexes allows for the incorporation of ligands with complementary properties, resulting in improved catalytic activity and selectivity. Schiff bases and thiazole derivatives have also been studied as ligands in catalytic systems, and their incorporation in mixed-ligand nickel(II) complexes could enhance the catalytic activity and selectivity of the complexes.

Mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives have also been studied for their potential applications in materials science. Nickel(II) complexes have been shown to exhibit interesting optical and magnetic properties, which make them attractive for various applications such as sensors, magnetic data storage, and optoelectronic devices. The use of mixed-ligand complexes allows for the incorporation of ligands with specific electronic and optical properties, resulting in improved properties of the resulting materials.

Overall, the development of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives represents a promising area of research with potential applications in medicine, catalysis, and materials science. The use of mixed-ligand complexes allows for the incorporation of different ligands with complementary properties, resulting in improved properties of the resulting complexes or materials. Further studies are needed to fully understand the properties and potential applications of these complexes and to optimize their properties for specific applications.

2 MATERIAL AND METHODS

The materials and methods used in the synthesis, characterization, and antimicrobial studies of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives may

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vary depending on the specific protocol used by the researchers. However, some common techniques and procedures that may be used in this type of study are:

Materials:

Aromatic aldehydes and amines for the synthesis of Schiff bases Nickel(II) chloride

Thiazole derivatives

Solvents such as ethanol, methanol, and dichloromethane

Reagents for elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and magnetic susceptibility measurements

Bacteria and fungi strains for antimicrobial studies 2.1 Methods:

Synthesis of Schiff bases: The Schiff bases are typically synthesized by mixing the appropriate aldehyde and amine in the presence of a suitable catalyst under reflux conditions. The reaction is monitored by TLC and stopped when the reaction is complete.

The Schiff bases are then purified by recrystallization or column chromatography.

Synthesis of mixed-ligand complexes: The mixed-ligand complexes are typically synthesized by mixing the Schiff base ligands with nickel(II) chloride and thiazole derivatives in a suitable solvent under reflux conditions. The reaction is monitored by TLC and stopped when the reaction is complete. The resulting complexes are purified by recrystallization or column chromatography.

Characterization: The complexes are characterized using various techniques such as elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and magnetic susceptibility measurements. The structures of the complexes are also determined using single-crystal X- ray diffraction analysis.

Antimicrobial studies: The antimicrobial activity of the complexes is evaluated against various bacteria and fungi using standard methods such as the disc diffusion assay and the broth microdilution method. The minimum inhibitory concentration (MIC) and the minimum bactericidal/fungicidal concentration (MBC/MFC) are determined for each complex.

Overall, the materials and methods used in the study of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives are designed to synthesize, characterize, and evaluate the properties of the complexes. These studies provide important information on the potential applications of these complexes as antimicrobial agents, catalysts, and materials.

3 RESULTS AND DISCUSSION

The results and discussion section of a study on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives typically presents the findings of the study and their implications. Some typical results and discussions may include:

Characterization: The results of elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and magnetic susceptibility measurements are presented to confirm the synthesis of the complexes and determine their physical and chemical properties. The results of single-crystal X-ray diffraction analysis are also presented to determine the molecular geometry and bonding interactions of the complexes.

Antimicrobial studies: The results of the antimicrobial studies are presented to evaluate the potential of the complexes as antimicrobial agents. The MIC and MBC/MFC values are determined for each complex against various bacteria and fungi, and the results are compared to those of standard antibiotics. The mechanisms of antimicrobial action of the complexes are also discussed, including their ability to interact with DNA, enzymes, and membranes.

Structure-activity relationships: The structure-activity relationships of the complexes are discussed based on their physical and chemical properties and antimicrobial activities. The effects of the Schiff base and thiazole derivatives on the properties and activities of the complexes are discussed, and the optimal design of ligands for the development of effective metal-based antimicrobial agents is proposed.

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Comparison with previous studies: The results of the study are compared to those of previous studies on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives, and the advantages and disadvantages of the current study are discussed. The implications of the findings for the development of new therapeutic strategies for infectious diseases and the design of effective metal-based complexes are also discussed.

Overall, the results and discussion section of a study on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives provides a comprehensive analysis of the properties and activities of the complexes and their potential applications in medicine and materials science. The section highlights the importance of ligand design in the development of effective metal-based complexes and provides insights into the mechanisms of antimicrobial action of these complexes.

In addition to the typical results and discussions mentioned earlier, a study on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives may include other relevant findings and discussions, such as:

Comparative studies: Comparative studies may be conducted between different mixed- ligand nickel(II) complexes with Schiff bases and thiazole derivatives to evaluate the effects of ligand variation on their properties and activities. The results of these studies can provide insights into the optimal design of ligands for specific applications and the potential limitations of the current ligand design strategies.

Toxicity studies: Toxicity studies may be conducted to evaluate the safety of the complexes for use in biological systems. The cytotoxicity of the complexes can be evaluated using standard methods such as the MTT assay, and their effects on cell viability, proliferation, and apoptosis can be assessed. The results of these studies can provide important information on the potential use of the complexes as therapeutic agents and their dose- limiting toxicities.

Molecular docking studies: Molecular docking studies may be conducted to evaluate the binding modes of the complexes with various biological targets, such as DNA and enzymes.

The results of these studies can provide insights into the mechanisms of action of the complexes and their potential as selective antimicrobial agents.

In vivo studies: In vivo studies may be conducted to evaluate the efficacy and safety of the complexes in animal models of infection. The pharmacokinetics, biodistribution, and toxicity of the complexes can be evaluated using standard methods, and their effects on microbial burden, inflammation, and tissue damage can be assessed. The results of these studies can provide important information on the potential use of the complexes as therapeutic agents in humans.

Overall, the results and discussion section of a study on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives can include various findings and discussions, depending on the specific objectives of the study. The section provides a comprehensive analysis of the properties and activities of the complexes and their potential applications in medicine and materials science, and highlights the importance of ligand design in the development of effective metal-based complexes.

4 CONCLUSION

The conclusion of a study on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives typically summarizes the key findings of the study and their implications. Some common points that may be included in the conclusion are:

The synthesis and characterization of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives have been successfully achieved using a two-step process involving the formation of Schiff bases followed by the reaction with nickel(II) chloride and thiazole derivatives.

The complexes have been characterized using various techniques such as elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, and magnetic susceptibility measurements. The structures of the complexes have also been determined using single- crystal X-ray diffraction analysis.

The antimicrobial studies have shown that the complexes exhibit good to moderate antimicrobial activities against various bacteria and fungi. The complexes have been shown

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to interact with multiple biological targets, including DNA, enzymes, and membranes, making them potentially effective against drug-resistant strains.

The structure-activity relationships of the complexes have been discussed based on their physical and chemical properties and antimicrobial activities. The effects of the Schiff base and thiazole derivatives on the properties and activities of the complexes have been evaluated, and the optimal design of ligands for the development of effective metal-based antimicrobial agents has been proposed.

The results of the study highlight the potential of mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives as antimicrobial agents and demonstrate the importance of ligand design in the development of effective metal-based complexes. The findings of the study could contribute to the development of new therapeutic strategies for infectious diseases and the design of effective metal-based materials and catalysts.

Overall, the conclusion of a study on mixed-ligand nickel(II) complexes with Schiff bases and thiazole derivatives summarizes the main findings of the study and their implications for future research and applications.

REFERENCES

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5. Wang, X. F., Liu, F., Song, X. Y., & Zhao, L. X. (2016). Schiff base metal complexes: synthesis, structure, and biological activity. Chemical Biology & Drug Design, 87(5), 649-657.

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