Thermal and Antibacterial Studies of Novel Lanthanide–Schiff Base Complexes

Abstract

Novel lanthanide complexes with the general formula [Ln(L)(ONO₂)(H₂O)₂] have been synthesized and characterized. {L = 5-bromosalicylidene 4-amino 3-mercapto-1,2,4-triazine-5-one (BrSAMT), Ln = La(III), Ce(III), (Pr(III) Eu(III), Sm(III), Nd(III), Tb(III), Dy(III), and Y(III)}. The thermal, magnetic, molar conductance, and spectral studies confirm that the ligand coordinates through sulfur, azomethine nitrogen, and phenolic oxygen. A scheme of thermal decomposition of the complexes is also proposed. La, Eu, and Yb complexes of BrSAMT show antibacterial activity against gram negative bacteria such as E. coli, Pseudomonas aeruginosa, Salmonella typhi, and Shigella flexneri.

Keywords:

• antibacterial studies
• lanthanide complexes
• thermal studies
• triazines

Acknowledgments

The authors thank the authorities of Department of Chemical Engineering, NITK Surathkal, for the TGA and biological activity studies, Shriram Institute of Industrial Research, Bangalore, and Indian Institute of Science, Bangalore, for the NMR spectra.