For the construction of well-defined hierarchical superstructures of pristine [60]fullerene (C60) arrays, pyrene-based molecular tweezers (PT) were used as host molecules for catching and arranging C60 guest molecules. The formation of host-guest complexes was systematically studied in solution as well as in the solid state. Two-dimensional proton nuclear magnetic resonance spectroscopic studies revealed that PT-host and C60-guest complexes were closely related to the molecular self-assembly of PT. Ultraviolet and fluorescence spectroscopic titrations indicated the formation of stable 1:1 and 2:1 (PT/C60) complexes. From the nonlinear curve-fitting analysis, equilibrium constants for the 1:1 (log K1) and 2:1 (log K2) complexes were estimated to be 4.96 and 5.01, respectively. X-ray diffraction results combined with transmission electron microscopy observations clearly exhibited the construction of well-defined layered superstructures of the PT-host and C60-guest complexes. From electron mobility measurements, it was demonstrated that the well-defined hierarchical hybrid nanostructure incorporating a C60 array exhibited a high electron mobility of 1.7 × 10-2 cm2 V-1 s-1. This study can provide a guideline for the hierarchical hybrid nanostructures of host-guest complex and its applications.
Keywords: dendron; fullerene; hierarchical nanostructure; host−guest complex; self-assembly.