Synthesis, characterization, and antimicrobial activity of a lanthanum complex with a triethylene glycol ligand

A La-TEG (triethylene glycol) complex was successfully synthesized, and isolated by a facile method and its structure was also completely determined by infrared, nuclear magnetic resonance (1H NMR and 13C NMR), energy-dispersive X-ray spectroscopy, and single-crystal X-ray diffraction. The La (III) centers were chelated by 1 TEG, 1 water molecules and 3 NO3– ions. The La-TEG complex exhibited significant antimicrobial activity against the growth of six microbacterial strains and one pathogenic yeast including Bacillus subtilis, Staphylococcus aureus, Lactobacillus fermentum (N4), Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa, and Candida albicans through in vitro assay. Furthermore, the investigation of the antimicrobial activity of La-TEG with different additives including Thymoquinone and Miramistin indicated that Miramistin could significantly boost the antimicrobial performance and spectrum. Specifically, the sample containing Miramistin and La-TEG complex displayed an excellent antimicrobial effect even after being diluted 1280 times when 1 wt of Miramistin was used as an additive. As a result, the minimum inhibitory concentrations (MICs) for both the La-TEG complex and Miramistin toward all test microorganisms were calculated to be 0.058 mg/mL and 7.8 µg/mL, respectively. © 2023 Elsevier B.V.