Synthesis and Photophysical Properties of a Supramolecular Host–Guest Assembly Constructed by Fullerenes and Tryptamine Modified Hypocrellin

Abstract

The metal coordination polymer of hypocrellin A bearing tryptamine motif (M-DTrpHA) can include fullerene via a two-point interaction, involving π-π stacking and electron donor-acceptor interaction. The 1:1 host-guest system M-DTrpHA/fullerene exhibits a moderate association constant K(a) (6.62 × 10(4) to 6.46 × 10(5) M(-1)). Both of the metal ions in M-DTrpHA and the substituents connected to the fullerene core play important roles in stabilizing the M-DTrpHA/fullerene complex. Transient absorption spectral and NIR absorption spectral results demonstrate that, in the M-DTrpHA/fullerene system, efficient photoinduced electron transfer from the tryptamine group in M-DTrpHA to fullerene may occur, resulting in a long-lived fullerene anion radical. The observed order of quantum yield (Φ(ET)(T)) and rate constants (K(ET)(T)) for electron transfer via (3)C(60)(*) is Y(3+)-DTrpHA > La(3+)-DTrpHA > DTrpHA, consistent with their binding ability to C(60). The nanostructure of M-DTrpHA is rearranged to form an interpenetrating network after interaction with fullerene.