Light‐Controlled Regioselective Synthesis of Fullerene Bis‐Adducts

Abstract

Multi-functionalization and isomer-purity of fullerenes are crucial tasks for the development of their chemistry in various fields.I nb oth current main approaches-tetherdirected covalent functionalization and supramolecular masks-the control of regioselectivity requires multi-step synthetic procedures to prepare the desired tether or mask. Herein, we describe light-responsive tethers,c ontaining an azobenzene photoswitcha nd two malonate groups,i nt he double cyclopropanation of [60]fullerene.T he formation of the bis-adducts and their spectroscopic and photochemical properties,a sw ell as the effect of azobenzene photoswitching on the regiochemistry of the bis-addition, have been studied. The behavior of the tethers depends on the geometry of the connection between the photoactive core and the malonate moieties.O ne tether lead to as trikingly different adduct distribution for the Ea nd Zi somers,i ndicating that the covalent bis-functionalization of C 60 can be controlled by light.

Si‐Tethered Bis‐ and Tris‐Malonates for the Regioselective Preparation of Fullerene Multi‐Adducts

“…Following this first example, the same group has developed direct macrocyclization reactions between bis‐malonate reagents and C 60 for the preparation of well‐defined fullerene bis‐adducts [9] . This powerful principle has been extensively used for the preparation of a wide range of regioisomerically pure fullerene bis‐adducts [10–23] . The synthesis of C 60 higher adducts is a more challenging task given the high number of possible isomers.…”

“…[9] This powerful principle has been extensively used for the preparation of a wide range of regioisomerically pure fullerene bis-adducts. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] The synthesis of C 60 higher adducts is a more challenging task given the high number of possible isomers. For instance, the number of theoretically possible regioisomers raises from 9 for C 60 bis-adducts to 46 for tris-adducts.…”