Synthesis, physicochemical and antimicrobial properties of rhenium (I) tricarbonyl complexes of isatin Schiff bases

Abstract

The Schiff base of isatin and sulphanilamide (L1; C14H11N3O3S) was prepared and reacted with Re(CO)5X (X = Cl and Br) in toluene to give [Re(C14H10N2O)(CO)3X] (X = Cl, 1 and X = Br, 2). The prepared Schiff base of isatin and 4-methoxyaniline (L2; C15H12N2O2) was reacted with Re(CO)5X in toluene to give [Re(C14H10N2O)(CO)3X], where X = Cl, 3 and X = Br, 4. L2 and Re(CO)5Br were refluxed in dry toluene under nitrogen and recrystallized to give [Re(C15H12N2O2)(CO)3Br].½C2H5OH (5). Spectroscopic characterization of compounds was done using FTIR, UV-Visible, NMR and Mass spectra analyses. Magnetic susceptibility measurements and melting points were also determined. Elemental analysis of 5 revealed it was a solvate molecule of 4. The in-vitro antimicrobial activities of compounds were evaluated against Staphylococcus aureus, Bacillus subtilis, Haemolytic Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella sp., Aspergillus niger, Trichoderma viride and Penicillium citrinum. Spectroscopic analyses revealed new terminal carbonyl bands formed between 1900 and 2030 cm-1, as L1 and L2 coordinated through their azomethine nitrogen and keto oxygen donor atoms towards Re(I). Results of the antimicrobial studies revealed immerse improved activities upon coordination against tested microorganisms especially gram-negative bacteria, therefore, they are recommended for further studies in cell imaging.