Bioactive Macrocyclic Ni(II) Metal Complex: Synthesis, Spectroscopic Elucidation, and Antimicrobial Studies

Abstract

A macromolecule schiff base derived from 3-acetyl-2H-benzo[h] chromen-2-one and naphthalene-1,8-diamine and its binuclear macrocyclic Ni(II) metal complex are reported. The ligand behaves as a pentadentate ligand when it coordinates with the metal ion as confirmed by different physical and spectroscopic techniques. Physicochemical and photophysical parameters such as extinction coefficient, oscillator strength, transition dipole moment, stokes shift, and fluorescence quantum yield of the binuclear Ni(II) metal complex were evaluated in the different solvents on the basis of solvents polarity. The thermal decomposition of the metal complex has been studied by thermogravimetric (TGA) and differential calorimetry (DSC). The macrocyclic Ni(II) metal complex was also used to determine of critical micelle concentration (CMC) of cationic and anionic surfactant such as cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The antibacterial behavior of the ligand and its metal complex revealed that they are active against both Gram-positive and Gram-negative bacteria, comparable to that of the reference drug Tetracycline. Metal complex showed enhanced activity compared to the ligand.

Keywords:

• Bis-schiff base
• macrocyclic complex
• stokes shift
• oscillator strength
• CMC

Acknowledgments

This project was funded by the Deanship of Scientific Research (DSR) at King Abdulaziz University, Jeddah, under grant no. (118-130-D1434). The authors, therefore, acknowledge with thanks DSR for technical and financial support.