Modulating Chalcogen Bonding and Halogen Bonding Sigma‐Hole Donor Atom Potency and Selectivity for Halide Anion Recognition

Abstract

A series of acyclic anion receptors containing chalcogen bond (ChB) and halogen bond (XB) donors integrated into a neutral 3,5‐bis‐triazole pyridine scaffold are described, in which systematic variation of the electronic‐withdrawing nature of the aryl substituents reveal a dramatic modulation in sigma‐hole donor atom potency for anion recognition. Incorporation of strongly electron‐withdrawing perfluorophenyl units appended to the triazole heterocycle telluro‐ or iodo‐ donor atoms, or directly linked to the tellurium donor atom dramatically enhances the anion binding potency of the sigma‐hole receptors, most notably for the ChB and XB receptors displaying over thirty‐fold and eight‐fold increase in chloride anion affinity, respectively, relative to unfluorinated analogues. Linear free energy relationships for a series of ChB based receptors reveal the halide anion recognition behaviour of the tellurium donor is highly sensitive to local electronic environments. This is especially the case for those directly appended to the Te centre (3⋅ChB), where a remarkable enhancement of strength of binding and selectivity for the lighter halides is observed as the electron‐withdrawing ability of the Te‐bonded aryl group increases, highlighting the exciting opportunity to fine‐tune anion affinity and selectivity in ChB‐based receptor systems.

Selective Potassium Chloride Recognition, Sensing, Extraction, and Transport Using a Chalcogen-Bonding Heteroditopic Receptor

“… 27 − 40 We have recently shown that ChB donor potency for anion recognition is markedly sensitive to local electronic environments, where electron-withdrawing fluoroaryl substituents operating via an inductive through-bond polarization mechanism effectively modulate ChB donor halide anion affinity and selectivity. 41 In addition, we have demonstrated redox-switchable on/off ChB anion binding and sensing mediation. 42 Despite the emergence of this unique ChB anion recognition behavior, the integration of ChB donors in heteroditopic ion-pair receptor design is extremely rare.…”

Halogen bonding and chalcogen bonding mediated sensing

“…This can be attributed to a variety of factors including a stricter adherence to a 180 binding geometry, lower solvent dependency, larger hydrophobicity and improved electronic tuneability. 14,16,28,29 These combined advantages have facilitated sigma-hole mediated anion recognition in aqueous media, importantly including pure water. [30][31][32] As a result, increasing attention is being directed at the application of this capability in transmembrane anion transport, [33][34][35][36][37] ion extraction and remediation 38,39 as well as anion sensing.…”

Noncovalent interactions in proteins and nucleic acids: beyond hydrogen bonding and π-stacking

“…In addition to the above examples, Chbonding also plays a significant role in anion transportation. [128][129][130] In a recent study, Matile and co-workers reported bis(perfluorophenyl)tellanes as a suitable candidate for anion transport due to the presence of Ch-bonds and adjacent p-acidic surfaces accounting for secondary anion-p interactions. They showed permeability P (Cl/Na) = 10.4 for anion/ cation selectivity and P (Cl/NO3) = 4.5 for anion selectivity.…”