π-Dimerization of viologen subunits around the core of C60 from twelve to six directions

Abstract

Molecular reorganization around the core of C-60 has been achieved by electron transfer centered on pi-dimerizable viologen subunits located in a restricted region of space. Fullerene C-60 hexaadducts, featuring 12 viologen subunits, have been prepared by using copper-mediated Huisgen 1,3-dipolar cycloaddition of azides with alkynes. Detailed electrochemical studies, supported by UV-Vis and EPR spectroscopic analyses, demonstrate that the linkers bearing the viologen subunits attached to specific positions around the all-carbon sphere, allow the formation of six intramolecular pi-dimers. Theoretical calculations reveal that the close proximity of the orbitals of the viologen subunits attached to the C-60 facilitate the pi-dimerization of the bis-radical species. These investigations support the fact that the motion of discrete peripheral groups oriented around the all-carbon sphere of C-60 can be controlled electrochemically using noncovalent reversible interactions

Synthesis of highly functionalized C60 fullerene derivatives and their applications in material and life sciences

“…88 Compound Scheme 30 Synthetic route to polycationic fullerene hexakisadducts. For instance, many efforts have been made to generate molecules in which electric stimulus results in molecular motions.…”

A Highly Luminescent Tetramer from a Weakly Emitting Monomer: Acid‐ and Redox‐Controlled Multiple Complexation by Cucurbit[7]uril

“…Among the multitude of chromophoric moieties investigated, pyridinium and bipyridinium chromophores (also known as viologens, namely, 1,1′‐disubstituted‐4,4′‐bipyridinium salts) are some of the most extensively studied functional entities by virtue of their photochemical and electrochemical properties 13. 14 They are widely employed as electron‐acceptor recognition sites and redox switching units in supramolecular systems such as dendrimers,15–18 rotaxanes,19–21 and catenanes 22. 23 Moreover, they have been investigated as components for electrochromic displays,24, 25 molecular batteries,26 redox mediators,27, 28 and redox sensors 29.…”

Radical‐Cation Dimerization Overwhelms Inclusion in [n]Pseudorotaxanes

“…More generally, the data lend credence to the idea that radical-cation dimerization (a relatively weak interaction) can be enhanced intramolecularly and exploited for the design of novel molecular switches. [88]…”