First Example of Cationic Cyclopentadienyliron Based Chromene Complexes and Polymers: Synthesis, Characterization, and Biological Applications

The present work encompasses development of a new class of active antimicrobial agents of the ɳ6-arene-ɳ5-cyclopentadienyliron (II) complexes and polymers to expand the existing family of antimicrobials. The design of the first example of these cationic organoiron complexes, incorporating chromene moieties, was successfully accomplished in good yield via the Steglich esterification, followed by the nucleophilic aromatic substitution reactions to isolate their polymeric analogues. Meanwhile, the structural identities of the new materials were confirmed using 1H and 13C NMR, IR, and elemental analysis. The molecular weight of the new polymeric materials was estimated using viscosity measurements, and was found to be in the range of 10,000 and 31,000. The chromene-containing organoiron complexes displayed reversible reduction behaviors as their functionalized polymers. Meanwhile, the TGA thermogram revealed initial weight losses due to the cleavage of the cationic iron moieties, while the second weight losses were dependent upon the etheric linkages in the polymer backbones. This study, therefore, focuses on the exploration of the antimicrobial and antitumor performance of the new materials along with their structure activity relationship.