β-Cyclodextrin Modified Imidazole Probe Specific Recognition of Organic Acids Based on Nuclear Magnetic Resonance

Supramolecular interaction plays an important role in molecular recognition. Cyclodextrins (CDs) are excellent hosts that are frequently utilized in identification of chemical compounds. Proper modifications to CD can give it the ability to accurately recognize specific molecules. In this research, CD was modified with allylimidazole moiety to generate synergistic effect. Remarkably, the newly formed cation probe exhibits selective recognition of 1-adamantanecarboxylic acid from six guest molecules, which cannot be achieved by CD or allylimidazole alone. The recognition is evidenced by the retention of hydrogen-deuterium exchange (HDX) properties in formed complexes and a change in the chemical shift of protons (H-4, H-5) in the allylimidazol backbone. Wavefunction analysis was employed to demonstrate the mechanism of molecular recognition is the electrostatic interaction between host and guest molecule as well as the hydrogen bond formed by the guest molecule with the imidazole moiety H-2. This work reports an intramolecular synergistic strategy to specifically identify 1-adamantanecarboxylic acid, which could inspire probe design for various analysts.