Substituent effects on cation-pi interactions: a quantitative study.

Hunter, Christopher A; Low, Caroline M R; Rotger, Carmen; Vinter, Jeremy G; Zonta, Cristiano · Proc Natl Acad Sci U S A · 2002

basic_science · Level V

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Abstract

A synthetic supramolecular complex has been adapted to quantify cation-pi interactions in chloroform by using chemical double-mutant cycles. The interaction of a pyridinium cation with the pi-face of an aromatic ring is found to be very sensitive to the pi-electron density. Electron-donating substituents lead to a strong attractive interaction (-8 kJ/mol(-1)), but electron-withdrawing groups lead to a repulsive interaction (+2 kJ/mol(-1)).

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