Polypyridyl iron() complexes containing long alkyl chains: synthesis, characterization, DFT calculations and biological activity

A polypyridyl ligand functionalized with a long alkyl chain ( L C10 ) was prepared. The reaction of L C10 with selected iron salts of different stoichiometries formed two metal complexes: [Fe( L C10 )(Cl) 3 ] ( 1 ) and [Fe( L C10 ) 2 ](ClO 4 ) 3 ·5H 2 O ( 2 ), which were fully characterized by a suite of physicochemical methods in which 1 had its crystal structure determined by XRD. The structural and spectroscopic data were tightly supported by DFT and TD-DFT calculations. The interaction between these two iron complexes and salmon sperm DNA was monitored spectrophotometrically in the UV region and binding constants ( K b ) were estimated and docking studies were performed using the PatchDock® server. Both complexes had their biocide activity confirmed against selected microorganisms: Gram-positive ( S. aureus ) and Gram-negative ( E. coli ) bacteria, A. fumigatus and S. cerevisiae with good values of MBC and IC 50 . Finally, the cytotoxic activities of 1 and 2 were probed against the erythroleukemia K562 cell line after 24, 48 and 72 h of incubation. For all biological studies, the magnitude of the activity followed the order: 2 > 1 > L C10 , which demonstrates the enhanced effect of iron when coordinated to the bioinspired ligand. A bis(picolyl)amine ligand was functionalized with a long alkyl chain, and two iron( iii ) complexes were prepared and their biological activity was presented.