Synthesis and characterization of novel ferrocenyl chalcone ammonium and pyridinium salt derivatives

Ferrocene donor linked to pyridine/pyridinium acceptor via a systematically enlarged π-linker

Nine chromophores with ferrocene donor and pyridine/pyridinium acceptors have been prepared and further investigated. The performed X-ray analysis showed partially polarized and geometrically oblate pyridine unit. An extension of the π-system and N-quaternization were revealed as suitable tools for exclusive manipulation of the LUMO with the almost steady HOMO. Whereas the electrochemical HOMO-LUMO gap can be tuned from 3.01 to 1.49 eV, the high- and low-energy absorption bands were found within the range of 280-402/456-547 nm. The pyridinium chromophores showed distinct negative solvatochromism. A thorough DFT analysis has been performed; it turned out that ferrocene donor is capable of two principal D-A interactions, whose employment depends on the appended electron-withdrawing moiety.

Perspectives of ferrocenyl chalcones: synthetic scaffolds toward biomedical and materials science applications

Ferrocene and its derivatives constitute versatile and interesting scaffolds for the global chemical enterprise due to its multiple applications that range from biomedical to materials science. Ferrocenyl derivatives are the leading compounds in our research for the syntheses and characterization as well as their potential biological applications. Among them, our recent focus has been in ferrocenyl chalcones as a framework for further derivatization. The proposed modifications consist on the incorporation of heterocyclic moieties into the ferrocenyl chalcone core. This can be afforded either by introducing a heterocyclic aromatic moiety as a substituent or functionalizing the α-β unsaturated system. Another modification explored is the formation of ammonium or pyridinium salts to increase water solubility. Studied ferrocenyl chalcones exhibit remarkable stability, physical, and electrochemical properties. These factors have led the approaches for them to be precursors of biologically active compounds (cancer, bacteria, malaria, and neurobiological diseases). Moreover, other potential applications include molecular materials, redox-sensors, and polymers. Our goal in this mini review is to highlight the chemistry of ferrocene derivatives with particular prominence to those ferrocenyl chalcones studied in our laboratory and their applications. Moreover, we are providing a background on ferrocene, chalcones, and ferrocenyl chalcones, emphasizing the methodologies with preeminent yields.