A Macrocycle Based on a Heptagon-Containing Hexa-peri-hexabenzocoronene

A cyclophane is reported incorporating two units of a heptagon-containing extended polycyclic aromatic hydrocarbon (PAH) analogue of the hexa-peri-hexabenzocoronene (HBC) moiety (hept-HBC). This cyclophane represents a new class of macrocyclic structures that incorporate for the first time seven-membered rings within extended PAH frameworks. The saddle curvature of the hept-HBC macrocycle units induced by the presence of the nonhexagonal ring along with the flexible alkyl linkers generate a cavity with shape complementarity and appropriate size to enable pi interactions with fullerenes. Therefore, the cyclophane forms host-guest complexes with C(60)and C(70)with estimated binding constants ofK(a)=420 +/- 2 m(-1)andK(a)=(6.49 +/- 0.23)x10(3) m(-1), respectively. As a result, the macrocycle can selectively bind C(70)in the presence of an excess of a mixture of C(60)and C-70.