Chalcogen Bond Mediated Enhancement of Cooperative Ion-Pair Recognition.

Thanthapatra Bunchuay,Panida Surawatanawong,Utt Eiamprasert,Asha Brown,Andrew Docker,Paul D Beer

doi:10.1002/anie.202001125

Abstract

A series of heteroditopic receptors containing halogen bond (XB) and unprecedented chalcogen bond (ChB) donors integrated into a 3,5‐bis‐triazole pyridine structure covalently linked to benzo‐15‐crown‐5 ether motifs exhibit remarkable cooperative recognition of halide anions. Multi‐nuclear 1H, 13C, 125Te and 19F NMR, ion pair binding investigations reveal sodium cation–benzo‐crown ether binding dramatically enhances the recognition of bromide and iodide halide anions, with the chalcogen bonding heteroditopic receptor notably displaying the largest enhancement of halide binding strength of over two hundred‐fold, in comparison to the halogen bonding and hydrogen bonding heteroditopic receptor analogues. DFT calculations suggest crown ether sodium cation complexation induces a polarisation of the sigma hole of ChB and XB heteroditopic receptor donors as a significant contribution to the origin of the unique cooperativity exhibited by these systems.

Highlights

We report a series of heteroditopic receptors containing halogen (1·XB), chalcogen (1·chalcogen bond (ChB)), and hydrogen bond (1·HB) donors integrated into a 3,5-bis-triazole pyridine structure for anion recognition which is covalently linked to benzo-15-crown-5 ether motifs for sodium cation binding (Figure 1)
The target chalcogen bonding heteroditopic receptor 1·ChB was successfully isolated in 15 % yield after preparative thin layer chromatographic purification
A series of novel heteroditopic receptors were synthesised, each containing benzo-15-crown-5 ether cation binding groups covalently attached to 3,5-bis-iodine, tellurium- and proton-functionalised-triazole pyridine anion binding motifs providing respective XB, unprecedented ChB and HB ion-pair receptors. 1H, 13C, 125Te and 19F NMR spectroscopy, ESI-MS and X-ray crystallography ion-pair binding studies demonstrate the cooperative recognition of bromide and iodide halide anions via concomitant sodium cation crown ether complexation of the respective heteroditopic receptor

Summary

Introduction

Charged species are ubiquitous, playing crucial roles in biology, medical healthcare and in particular in the environment resulting from polluting anthropogenic chemical industry activities. We report a series of heteroditopic receptors containing halogen (1·XB), chalcogen (1·ChB), and hydrogen bond (1·HB) donors integrated into a 3,5-bis-triazole pyridine structure for anion recognition which is covalently linked to benzo-15-crown-5 ether motifs for sodium cation binding (Figure 1).

Results

Conclusion