ALarge π-Extended Carbon Nanoring Based on Nanographene Units: Bottom-Up Synthesis, Photophysical Properties, and Selective Complexation with Fullerene C70

Herein we report the organoplatinum-mediated bottom-up synthesis, characterization, and properties of a novel large pi-extended carbon nanoring based on a nanographene hexa-peri-hexabenzocoronene (HBC) building unit. This tubular structure can be considered as an example of the longitudinal extension of the cycloparaphenylene scaffold to form a large pi-extended carbon nanotube (CNT) segment. The cyclic tetramer of a tetramesityl HBC ([4] CHBC) was synthesized by the reaction of a 2,11-diborylated hexa-peri-hexabenzocoronene with a platinum complex, followed by reductive elimination. The structure of this tubular molecule was further confirmed by physical characterization. Theoretical calculations indicate that the strain energy of this nanoring is as high as 49.18 kcal mol(-1). The selective supramolecular host-guest interaction between [4]CHBC and C-70 was also investigated.