Probing a Hydrogen‐π Interaction Involving a Trapped Water Molecule in the Solid State

Abstract

AbstractThe detection and characterization of trapped water molecules in chemical entities and biomacromolecules remains a challenging task for solid materials. We herein present proton‐detected solid‐state Nuclear Magnetic Resonance (NMR) experiments at 100 kHz magic‐angle spinning and at high static magnetic‐field strengths (28.2 T) enabling the detection of a single water molecule fixed in the calix[4]arene cavity of a lanthanide complex by a combination of three types of non‐covalent interactions. The water proton resonances are detected at a chemical‐shift value close to zero ppm, which we further confirm by quantum‐chemical calculations. Density Functional Theory calculations pinpoint to the sensitivity of the proton chemical‐shift value for hydrogen‐π interactions. Our study highlights how proton‐detected solid‐state NMR is turning into the method‐of‐choice in probing weak non‐covalent interactions driving a whole branch of molecular‐recognition events in chemistry and biology.