Chapter 4. Functional Molecular and Supramolecular Materials for Electron Transfer Reactions and their Applications

This chapter describes some of the most extensively investigated π-conjugated scaffolds, which have the inherent ability to accept one or more electrons. Thus, the progress of the knowledge of well-known electron acceptors in recent times is deliberated. The focus of the chapter has been to highlight the new developments in the direction of design and synthesis of ambient stable open-shell, multi-anionic and multi-radical based systems and their new age applications. It is realized that weak intramolecular and intermolecular noncovalent interactions play pivotal role towards the delocalization of the unpaired electron and stability of the system. The significance of molecular and crystal engineering principles is discussed, which allow efficient transport of electrons in highly electron deficient systems to confer high charge mobility. The recent advances in molecular design approaches towards non-fullerene based electron acceptors for organic solar cells are illustrated. The photophysical properties of the excited doublet states of these radical anions have been discussed, which have shown that it is possible to control the movement of electrons within a multisite donor–acceptor array on a femtosecond time scale. In addition, the application of the photoexcited radical ions towards C–C bond formation reactions and aryl halide reduction is elucidated. Furthermore, the applications of the radical ions as probes to sense toxic analytes utilizing their attractive multi-channel absorption properties are explained. Finally, we examine the recent progress made en route to utilizing these π-conjugated electroactive materials for organic Li ion batteries.