Fullerenes (C60/C70)-Embedded Copper(I)-Imidazole/Pyrazolate Macrocycles: Synthesis, Structures, and Electronic Properties.

Four C60/C70-embedded copper(I)-imidazole/pyrazolate macrocyclic supramolecular complexes were synthesized through a facile one-pot solvothermal approach. The structural difference between Ih-C60 and D5h-C70 effectively templates chair- and boat-like macrocyclic conformations, respectively. Tuning the ligand ratio yields additional cyclic trinuclear Cu3Pz3 clusters anchored on boat-like macrocycles via π-acid···Cl interactions, further constructing 2-fold interpenetrated crs topological networks. Combined Hirshfeld surface, independent gradient model based on Hirshfeld Partition (IGMH) analysis, and energy decomposition analyses (EDA) demonstrate that host-guest interactions between fullerene and macrocycle are dominated by dispersion forces, and C70 exhibits stronger binding affinity than C60. Spectroscopic experiments and time-dependent density functional theory (TD-DFT) calculations reveal that synergistic (Cu, Cl) → π*(fullerene) charge transfer and π → π* transitions within fullerenes cause their broad absorption, with the enhanced intrinsic visible-light absorption of C70 in C70-embedded complexes. This work establishes a clear structure-property relationship for the rational design of fullerene-based optoelectronic supramolecular materials.