A Supramolecular Strategy to Modulate the Photoluminescence of Metallofullerenes via Motion-Induced Phosphorescence Attenuation

Yttrium-based metallofullerenes have attracted much attention due to their typical photoluminescence properties with thermally activated delayed fluorescence (TADF) and phosphorescence, which have the potential for photofunctional materials. In this work, a supramolecular strategy to modulate the TADF and phosphorescence of metallofullerene Y 3 N@C 80 with a molecular nanoring is reported. A supramolecular complex Y 3 N@C 80 ⊂[9]CPPH was first constructed by Y 3 N@C 80 and a molecular nanoring of [9]CPPH. Temperature-dependent photoluminescence measurements revealed that Y 3 N@C 80 ⊂[9]CPPH retains the characteristic TADF band at 700 nm and phosphorescence-dominated band at 738 nm, respectively. However, Y 3 N@C 80 ⊂[9]CPPH shows significantly amplified TADF emission as well as decreased phosphorescence compared to that of pristine Y 3 N@C 80 . This phenomenon can be ascribed to the existing dynamic motion of Y 3 N@C 80 inside the nanocavity of molecular nanoring, which could result in nonradiative decay of triplet states and suppress the phosphorescence emission finally. Density functional theory calculations of Y 3 N@C 80 ⊂[9]CPPH were employed to illustrate the structure and excited states. Thus, this host–guest interaction provides a new strategy for tuning the photoluminescence of metallofullerene optical materials via motion-induced phosphorescence modulation.