A Long‐Lived Azafullerenyl Radical Stabilized by Supramolecular Shielding with a [10]Cycloparaphenylene

Abstract

Am ajor handicap towards the exploitation of radicals is their inherent instability.I nt he paramagnetic azafullerenyl radical C 59 NC,t he unpaired electron is strongly localized next to the nitrogen atom, which induces dimerization to diamagnetic bis(azafullerene), (C 59 N) 2 .C onventional stabilization by introducing steric hindrance around the radical is inapplicable here because of the concave fullerene geometry. Instead, we developed an innovative radical shielding approach based on supramolecular complexation, exploiting the protection offered by a[ 10]cycloparaphenylene ([10]CPP) nanobelt encircling the C 59 NC radical. Photoinduced radical generation is increased by af actor of 300. The EPR signal showing characteristic 14 Nh yperfine splitting of C 59 NC& [10]CPP was traced even after several weeks,w hichc orresponds to alifetime increase of > 10 8 .The proposed approach can be generalized by tuning the diameter of the employed nanobelts,opening new avenues for the design and exploitation of radical fullerenes.

Tuning the stability of organic radicals: from covalent approaches to non-covalent approaches

“…53 Supramolecular steric protection can provide another approach to stabilize radicals under some special conditions, where conventional steric substituents are not applicable. Most recently, Tagmatarchis et al reported an exciting study of a long-lived azafullerenyl radical stabilized by supramolecular shielding with [10]cycloparaphenylene ([10]CPP) 54 (Fig. 8).…”

Implications of Nitrogen Doping on Geometrical and Electronic Structure of the Fullerene Dimers

“…Toward solid materials, assemblies of molecular C 60 into oligomers such as dimers have attracted attentions of chemists. [ 2‐4 ] In 1992, Yeretzian et al . [ 5 ] first discovered the coalescence of fullerene when they conducted mass spectrometric test on the hot vapors of C 60 and C 70 under laser irradiation, but the degree of polymerization between carbon cages is uncontrolled in the experiment.…”

Probing the efficiency of thermal and photochemical bond homolysis in functionalized nanostructured SBA-15 silicas

“…In the other group, the paramagnetic species associate through non-bonding interactions to afford a wide array of systems capable to provide confinement. Porous materials (zeolite [8,9], AlMCM-41 [10]) and cage molecules (cucurbit [n]urils [11,12,13,14], cyclophanes [15], cyclodextrins [16], single-wall carbon nanotubes [17,18]) can be found in this latter group.…”