Facile and reliable emission‐based nanomolar anion sensing by luminescent Iridium receptors featuring chelating halogen bonding sites

Kampes, Robin; Tepper, Ronny; Görls, Helmar; Bellstedt, Peter; Jäger, Michael; Schubert, Ulrich S.
An anion sensor is presented that combines a bidentate hydrogen‐ or halogen bonding site with a luminescent monocationic Ir‐fragment for strong binding of common anions (Ka up to 6 × 104 M‐1) by diagnostic emission changes. A novel emission‐based protocol for the fast and reliable detection has been derived, relying on the correction for systematic but unspecific background effects. Such simple correction routine circumvents the hitherto practical limitations for systematic emission‐based analysis of anion binding using validated open‐sorce software (BindFit). The anticipated order of Ka values was obeyed according to size and basicity of the anions (Cl > Br ≈ OAc) as well as the receptor’s donor atom (XB: 6 × 104 M‐1 > HB: 5 ×103 M‐1), leading to sub‐micromolar limits of detetion within minutes. The results were further validated by advanced NMR techniques, and corroborated by crystallographic X‐ray data and DFT analysis, which reproduced the structural and electronic features in excellent agreement. The results suggests, that the corrected emission‐based sensing may become a complementary, reliable and fast tool to promote the use of XB in various application fields, arising from the simple and fast optical determination at high dilution.
Type of Publication:
Chemistry a European Journal