Iodide Discrimination by Tetra‐Iodotriazole Halogen Bonding Interlocked Hosts

Abstract

Whilst the exploitation of interlocked host frameworks for anion recognition is widely established, examples incorporating halogen bond donor groups are still relatively rare. Through the integration of an ovel tetra(iodotriazole)pyridinium motif into macrocycle and axle components,a family of halogen bondingc atenane and rotaxanes are constructed for anionr ecognition studies in ac ompetitive aqueous-organic solventm ixture. Importantly,t he degree of anion selectivity displayed is dictated by the topological nature and charged state of the respective interlocked host cavity.A ll the interlocked hosts exhibit iodide anionselectivity over other halidesa nd sulfate, with the level of discrimination being the greatest with the mono-cationic rotaxane. Arising from greater electrostatic interactions working in tandem with halogen bonding and hydrogen bonding, the di-cationic rotaxane displays stronger anion associationa t the expense of ar elatively lower degree of iodide selectivity.

Neutral Chiral Tetrakis‐Iodo‐Triazole Halogen‐Bond Donor for Chiral Recognition and Enantioselective Catalysis

“…As anticipated, the binding constants towards halides and acetate for the XB‐donor 1 were significantly higher compared to the HB‐donor 2 (entries 1–4; for example, 1.1×10 3 m −1 vs. 99 m −1 for Cl − ) [3e, 5e–h,j] . In accordance with previous reports of multidentate XB‐donors, receptor 1 displayed selectivity towards I − , with an affinity of 3.6×10 3 m −1 , more than 40‐fold higher than that of the HB‐donor 2 (entry 3) [21] . Interestingly, for bisulfate‐, hydrogen phosphate‐ and nitrate, 1 showed low to no binding (entries 5–7), while the HB‐donor 2 bound to these anions in preference to the halides.…”

Exploiting the mechanical bond for molecular recognition and sensing of charged species

“…20). 71 Interestingly, significant differences in anion binding strengths were observed for these MIMs. Although both 39 and 40 are monocationic, rotaxane 40•PF6 bound iodide almost three times stronger than catenane 39•PF6 in CDCl3/CD3OD/D2O 45:45:10.…”

Forty years of progress in the study of the hydrogen bond

“…These relatives of the HB are hardly exotic academic novelties, but have a wide range of applications, such as serving as synthons in self-assembling networks [117], biological catalysis [118], oxidative addition [119], self-assembled monolayers [120], SN2 reaction catalysis [121], design of functional mesomorphic materials [122], and even directed construction of supramolecular quadruple and double helices [123]. One of the more interesting uses concerns selective binding of anions [124][125][126][127][128][129][130][131]. It was realized that the replacement of the H atom of certain multidentate anion receptors with a halogen atom allowed them to engage in halogen bonds with an anion, which in turn strengthened the interaction, and enhanced the selectivity for certain anions over others.…”