Remote Control of Anion-? Catalysis on Fullerene-Centered Catalytic Triads.

ABSTRACT: The design, synthesis and evaluation of catalytic triads composed of a central C60 fullerene with an amine base on one side and polarizability enhancers on the other side are reported. According to an enolate addition benchmark reaction, fullerene-fullerene-amine triads display the highest selectivity in anion-? catalysis observed so far, whereas NDI-fullerene-amine triads are not much better than fullerene-amine controls (NDI=naphthalenediimide). These large differences in activity are in conflict with the small differences in intrinsic ? acidity, that is, LUMO energy levels and ? holes on the central fullerene. However, they are in agreement with the high polarizability of fullerene-fullerene-amine triads. Activation and deactivation of the fullerene-centered triads by intercalators and computational data on anion binding further indicate that for functional relevance, intrinsic ? acidity is less important than induced ? acidity, that is, the size of the oriented macrodipole of polarizable ? systems that emerges only in response to the interaction with anions and anionic transition states. The resulting transformation is thus self-induced, the anionic intermediates and transition states create their own anion-? catalyst.

SUBMITTER: Lopez-Andarias J 

PROVIDER: S-EPMC6120490 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature