%0 Journal Article
%A Bornhof, Anna Bea
%A Vázquez Nakagawa, M.
%A Rodríguez Pérez, Laura
%A Herranz, M.Angeles
%A Sakai, Naomi
%A Martín, Nazario
%A Matile, Stefan
%A López Andarias, Javier
%T Anion-π Catalysis on Carbon Nanotubes
%D 2019
%@ 1433-7851
%U https://hdl.handle.net/20.500.14352/5994
%X Induced π acidity from polarizability is currently emerging as most effective to stabilize anionic transition states on aromatic π surfaces, that is anion-π catalysis. To access extreme polarizability, we here propose a shift of attention from homogeneous toward heterogeneous anion-π catalysis on higher carbon allotropes. According to benchmark enolate addition chemistry, multi-walled carbon nanotubes equipped with tertiary amine bases outperform single-walled carbon nanotubes clearly. This difference is consistent with polarizability of the former not only along but also between the tubes. Inactivation by π-basic aromatics and saturation with increasing catalyst concentration support that catalysis occurs on the π surface of the tubes. Increasing rate and selectivity of existing anion-π catalysts (naphthalenediimides > fullerenes) on the Surface of unmodified nanotubes is consistent with transition-state stabilization by electron sharing into the tubes, i.e., induced anion-π interactions. On pristine tubes, anion-π catalysis is realized by noncovalent interfacing with π-basic pyrenes.
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