Exploring the Capability of Mechanically Interlocked Molecules in Anion Recognition: A Computational Insight

Abstract

The present study elucidated the role of both hydrogen and halogen bonds, from an electronic structure perspective, in the anion recognition process by the [2]catenane (1) containing a moiety with hydrogen bond donors entangled with another macrocyclic halogen bond donor. Spherical and nonspherical anions have been employed. The roles of different σ–hole donors have also been considered. The structure of 1 was modified by incorporating other σ–hole donors, namely bromine, chlorine, fluorine, as well as −Te–CH₃ as a chalcogen bond donor, leading to the modified [2]catenanes 2–5. Insights into anion recognition were gained by quantifying the contributions of not only the mechanical but also hydrogen and halogen/chalcogen bonds to anion recognition using the GKS-EDA energy partition scheme and homodesmostic reactions scheme. GKS-EDA reveals that the anions Cl^– and TS^– exhibit the most stabilizing interactions with the 1 binding pocket. The EDA results confirm that by changing from a stronger σ-hole donor (I) to a weaker σ-hole donor (F) will have a considerable impact on anion interaction, thereby demonstrating that the halogen bonds formed between the [2]catenane and the anion play a pivotal role.