Bis-corannulene Receptors for Fullerenes Based on Klärner’s Tethers: Reaching the Affinity Limits
摘要:
Bis-corannulene receptors 4 and 5 with Khmer's tethers prepared by the Diels-Alder cycloaddition form inclusion complexes with C-60 and C-70, as evidenced by H-1 NMR titration. While 4 exhibits affinity toward fullerenes comparable to the previously reported corannulene-based receptors, 5 exceeds the performance of the former systems by ca. 2 orders of magnitude and, in addition, shows an enhanced preference for C-70 over C-60. The X-ray crystal structure of C-60@5 and DFT calculations indicate that the tether in 5 not only preorganizes the pincers into a proper topology of the host but also contributes to the dispersion-based binding with the fullerene guests.