Cyclotriveratrylene-Containing Porphyrins.

The C3-symmetric cyclotriveratrylene (CTV) was covalently bonded via click chemistry to 1, 2, 3, and 6 zinc(II) porphyrin units to various host for C60. The binding constants, Ka, were measured from the quenching of the porphyrin fluorescence by C60. These constants vary between 400 and 4000 M(-1) and are considered weak. Computer modeling demonstrated that the zinc(II) porphyrin units, [Zn], exhibit a strong tendency to occupy the CTV cavity, hence blocking the access for C60 to land on this site. Instead, the pincer of the type [Zn]----[Zn] and in one case [Zn]----CTV, were found to be the most probable geometry to promote host-guest associations in these systems.