Issue 26, 2020

Electrostatics does not dictate the slip-stacked arrangement of aromatic π–π interactions

Abstract

Benzene dimer has long been an archetype for π-stacking. According to the Hunter–Sanders model, quadrupolar electrostatics favors an edge-to-face CH⋯π geometry but competes with London dispersion that favors cofacial π-stacking, with a compromise “slip-stacked” structure emerging as the minimum-energy geometry. This model is based on classical electrostatics, however, and neglects charge penetration. A fully quantum-mechanical analysis, presented here, demonstrates that electrostatics actually exerts very little influence on the conformational landscape of (C6H6)2. Electrostatics also cannot explain the slip-stacked arrangement of C6H6⋯C6F6, where the sign of the quadrupolar interaction is reversed. Instead, the slip-stacked geometry emerges in both systems due to competition between dispersion and Pauli repulsion, with electrostatics as an ambivalent spectator. This revised interpretation helps to rationalize the persistence of offset π-stacking in larger polycyclic aromatic hydrocarbons and across the highly varied electrostatic environments that characterize π–π interactions in proteins.

Graphical abstract: Electrostatics does not dictate the slip-stacked arrangement of aromatic π–π interactions

Supplementary files

Article information

Article type
Edge Article
Submitted
10 May 2020
Accepted
02 Jun 2020
First published
05 Jun 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2020,11, 6758-6765

Electrostatics does not dictate the slip-stacked arrangement of aromatic π–π interactions

K. Carter-Fenk and J. M. Herbert, Chem. Sci., 2020, 11, 6758 DOI: 10.1039/D0SC02667K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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