Multi-Functional Modification of Schiff Bases Based Upon Ferrocene

In this review, ferrocenyl enaminones stabilized by nitrogen- and oxygen-containing bi-, tri-, and tetradentate Schiff bases, as well as chiral ferrocenylamino alcohols are summarized. UV-Vis, IR (the C = N stretching vibration in the range of 1519 ~ 1661 cm−1), and 1H NMR (the chemical shift of CH = N in the range of 7.83 ~ 9.34 ppm) spectra collectively confirm the formation of ferrocenyl-Schiff bases (−CH = N−). Additionally, ferrocenyl-Schiff base ligands exhibit good coordinating ability and have been reported to coordinate with several transition metals (copper, nickel, cobalt and ruthenium). Sections of this review are dedicated to discussing the synthesis, structures and electrochemical properties of selected representative Schiff bases and their metal complexes. Overall, the development of novel ferrocene-derived Schiff bases has been recognized as a pivotal research direction in ferrocene chemistry because of the excellent coordination capability, thermal stability, electrochemical properties, and bioactivity of the imine groups. This review describes the synthesis of the main types of multifunctional ferrocene-based Schiff bases and their broad applications in electrochemistry, biochemistry and hair dyeing applications.