Synthesis, Characterization And Evaluation Of The Biological Activities Of Copper (Ii), Zinc (Ii) And Nickel (Ii) Schiff Base Complexes Of Quinoline Derivative Ligands

Abstract

The Rise Of Drug-Resistant Bacterial Infections Has Become A Critical Global Health Concern That Demands Immediate Attention. Owing To Their Unique Chemical Structures And Properties, Transition Metal Complexes Of Schiff Base Ligands Offer Innovative Bioactivities And Functionalities That Make Them Valuable Candidates For Developing New Drug Candidates To Counter The Growing Threat Of Multidrug-Resistant Pathogens. In This Study, Novel Schiff Base Ligands Derived From A Quinoline Derivative And Amino Acids, And Their Ni(Ii), Cu(Ii) And Zn(Ii) Complexes Were Synthesized, Characterized, And Evaluated For Their Biological Activities. Two Schiff Base Ligands, Namely (E)-2-(((7-Chloro-2-Hydroxyquinolin-3-Yl)Methylene)Amino)-3-Phenylpropanoic Acid (Sbl1) And (E)-2-(((7-Chloro-2-Hydroxyquinolin-3-Yl)Methylene)Amino)-3-Methylbutanoic Acid (Sbl2), From 2,7-Dichloroquinoline-3-Carboaldehyde And Phenylalanine/Valine. Subsequently Their Metal (Ii) Complexes Nisbl1, Cusbl1, Znsbl1, Nisbl2, Cusbl2, And Znsbl2 Were Synthesized And Characterized Using Various Spectroscopic Techniques Such As Uv-Vis, 1h-Nmr, 13c-Nmr, Ft-Ir, And Pxrd. Analysis Of The Ft-Ir Spectra Confirmed The Tridentate Nature Of The Schiff Base Ligands (Sbl1 And Sbl2) With Ono Active Binding Sites. The Pxrd Analysis Indicated That Cusbl2 Possessed Amorphous Nature And The Rest Two Are Crystalline In Nature. The Antibacterial Properties Of These Compounds Were Evaluated Using The Disc Diffusion Method. Notably, The Cusbl1 Complex Exhibited Superior Antibacterial Activity Against Various Strains Compared To The Other Synthesized Complexes, Attributed To Its Small Crystalline Size Of 29.7 Nm As Determined By Pxrd Results. Furthermore, Sbl1 And Sbl2 Demonstrated Antibacterial Efficacy Against B. Cereus, S. Aureus, E. Coli, S. Typhi, And C. Albicans, With Varying Degrees Of Inhibition At A Concentration Of 100 ??G/Ml. Znsbl1, Nisbl1, And Cusbl1 Complexes Also Displayed Antibacterial Activities Against These Strains At The Same Concentration, With Cusbl1 Showing The Highest Activity. Additionally, Sbl2 And Its Metal Complexes Exhibited Antibacterial Effects Against Different Strains At Concentrations Of 100 ??G/Ml And 200 ??G/Ml, With Cusbl2 Demonstrating The Strongest Antibacterial Activity Compared To The Other Two Nisbl2 And Znsbl2 Complexes. Overall, This Study Highlights The Potential Of Schiff Base Compounds And Their Metal Complexes As Promising Candidates For Combating Drug-Resistant Microbial Infections, Particularly Cusbl1 And Cusbl2 Showing Notable Antibacterial Efficacy Warranting Next Level Investigation.