Anion Receptors Based on Halogen Bonding with Halo-1,2,3-triazoliums

Tepper, Ronny; Schulze, Benjamin; Jäger, Michael; Friebe, Christian; Scharf, Daniel H.; Görls, Helmar; Schubert, Ulrich S.

Abstract:

A systematic series of anion receptors based on bidentate halogen bonding by halo-triazoles and -triazoliums is presented. The influence of the halogen bond donor atom, the electron-withdrawing group, and the linker group that bridges the two donor moieties is investigated. Additionally, a comparison with hydrogen bond-based analogues is provided. A new, efficient synthetic approach to introduce different halogens into the heterocycles is established using silver(I)-triazolylidenes, which are converted to the corresponding halo-1,2,3-triazoliums with different halogens. Comprehensive nuclear magnetic resonance binding studies supported by isothermal titration calorimetry studies were performed with different halides and oxo-anions to evaluate the influence of key parameters of the halogen bond donor, namely, polarization of the halogen and the bond angle to the anion. The results show a larger anion affinity in the case of more charge-dense halides as well as a general preference of the receptors to bind oxo-anions, in particular sulfate, over halides.

Year:

2015

Type of Publication:

Article

Journal:

Journal of Organic Chemistry

Volume:

80

Pages:

3139 - 3150