Related Experiment Video
Updated: Jun 20, 2026

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Counterintuitive substituent effect of the ethynyl group in ion-pi interactions
Xavier Lucas1, David Quiñonero, Antonio Frontera
1Departament de Química, Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain.
Abstract:
In this article, we report a high-level theoretical study (SCS-RI-MP2(full)/aug-cc-pVTZ) that deals with the substituent effect of the ethynyl group on ion-pi interactions in 1,3,5-triethynylbenzene systems. The ethynyl group is able to act as an electron-withdrawing group, thus favoring the anion-pi interaction. Unexpectedly, it has little influence on the cation-pi interaction. This behavior has been studied by examining the geometrical and energetic features of the complexes, AIM, and charge analyses and partitioning the interaction energy. The simultaneous interaction of 1,3,5-triethynylbenzene with cations and anions by opposite sides of the ring has also been studied.
Related Concept Videos
π Electron Effects on Chemical Shift: Overview
Directing Effect of Substituents: meta-Directing Groups
Directing Effect of Substituents: ortho–para-Directing Groups
Inductive Effects on Chemical Shift: Overview
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Directing and Steric Effects in Disubstituted Benzene Derivatives

