Supramolecular Fullerene Sponges as Catalytic Masks for Regioselective Functionalization of C60

Abstract

An unprecedented and straightforward supramolecular mask strategy to prepare exclusively equatorial bis-, tris-, and tetrakis-cyclopropanated-C 60 Bingel-Hirsch derivatives is reported. By taking advantage of the high affinity for fullerene of tetragonal prismatic supramolecular cages, a highly stable C 60 31a$(BArF) 8 hostguest complex is submitted to Bingel-Hirsch cyclopropanation reaction conditions. Regioselectivity is strictly dictated by the four cross-shaped apertures of the nanocapsule in a controlled fashion. Moreover, stepwise-cyclopropanated adducts up to tetrakis additions are obtained in excellent yields and purities.

A covalent organic cage compound acting as a supramolecular shadow mask for the regioselective functionalization of C60

“…33 Building upon this inherent selectivity, Ribas and coworkers reported on the exclusive formation of the all-equatorial tetrakisadduct for Bingel reactions on a complex of C 60 within a tetragonal prismatic metallosupramolecular cage. 26 For the Prato reaction however, a much broader distribution of all eight possible bisadducts is usually observed (Fig. S12b †).…”

“…25 The square-planar arrangement of the four cage windows for a metallosupramolecular fullerene sponge was recently utilized for the exclusive formation of all-e Bingel tetrakisadducts of C 60 , even under catalytic conditions. 26 This masking strategy provides a signicant improvement over the multistep orthogonal transposition approach 27 as the so far only practicable synthetic route for this addition pattern. Despite these initial examples, no cage templates to control the inherently less selective Prato reaction have been reported so far.…”

A Covalent Organic Cage Compound Acting as a Supramolecular Shadow Mask for the Regioselective Functionalization of C60

“…33 Building upon this inherent selectivity, Ribas and coworkers reported in the exclusive formation of the all-equatorial tetrakisadduct for Bingel reactions on a complex of C60 within a tetragonal prismatic metallosupramolecular cage. 26 For the Prato reaction however, a much broader distribution of all eight possible bisadducts is usually observed (Fig. S12b †).…”

“…25 The square-planar arrangement of the four cage windows for a metallosupramolecular fullerene sponge was recently utilized for the exclusive formation of all-e Bingel tetrakisadducts of C60, even under catalytic conditions. 26 This masking strategy provides a significant improvement over the multistep orthogonal transposition approach 27 as the so far only practicable synthetic route for this addition pattern. Despite these initial examples, no cage templates to control the inherently less selective Prato reaction have been reported so far.…”

Directional asymmetry over multiple length scales in reticular porous materials

“…Different applications based on directional asymmetric systems over multiple length scales from microscale (left) to macrosca le (right). At the molecular scale possible application arising from directional asymmetry are (a) molecular recognition based on dissymmetric diastereoisomers capsules,81 (b) asymmetric functionalization of fullerene using metal-organic cage as a mask template 82. At the mesoscale, applications are (c) gas separation thanks to the different polarity of MOF-on-MOF structures (adapted with permission from ref.…”