Inclusion complexes of buckycatcher with C60 and C70

Abstract

The dispersion corrected B97-D functional studies find a previously overlooked conformer of the buckycatcher C(60)H(28) (2) exhibiting intramolecular pi-pi stacking of its corannulene pincers to represent a global potential energy minimum conformation. B97-D/TZVP calculated geometry of C(60)@2 supramolecular assembly is in excellent agreement with the X-ray structure, slightly better than the previously reported M06-L results. In contrast, our calculated binding energy of C(60)@2 complex is dramatically higher than both M05-2X and M06-2X results and we conclude that the latter numbers are grossly underestimated. The lack of specificity of the buckycatcher for molecular recognition of C(60)vs. C(70) fullerenes is predicted by our calculations and confirmed by the NMR titration experiment which provides the equilibrium constant of 6800 +/- 400 M(-1) for association of C(70) with C(60)H(28) which is only slightly lower than the previously reported association constant of C(60)@2 assembly.