Orientation-dependent electron transfer processes in fullerene-aniline dyads

Abstract

Newly synthesized ortho- and para-substituted fullerene-aniline dyads exhibit orientation-dependent electron transfer under photoexcitation. Minimum energy conformation based on molecular mechanics calculations yield folded conformations for ortho-substituted dyads and extended ones for the para-substituted dyads. ¹H NMR studies also provided evidence for the folding of the anilinic group in the case of ortho-substituted dyads. Through-space charge transfer processes in these dyads were investigated using steady state fluorescence and lifetime measurements. The decrease in the spatial distance between the donor and acceptor moieties of the ortho-substituted dyads facilitated an efficient electron transfer. The marked increase in the singlet excited state deactivation rate constants and quantum yields of charge separation observed in the case of the ortho-substituted dyads, in polar solvents, further support a topographically controlled electron transfer process.