Host-guest interaction between cucurbit[6]uril and chain amino acids

Highlights: • A three-step method was established to explore the host–guest binding interaction between chain amino acids and CB[6]. • The experimental results indicated that the binding affinity of CB[6] to amino acids is Met > Leu > Val. • This work helps to develop the new approach for the identification and sensing of amino acids, to research the interaction pattern of other molecular recognition in chemistry, and to broaden the understanding of macrocyclic supramolecules. The interaction between cucurbit[6]uril and chain amino acids was studied via fluorescence probe method, molecular simulation, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The experimental results of this work show that the cucurbit[6]uril host possesses a strong binding force with the chain amino acids leucine and methionine, and can form a host–guest inclusion complex. At the same time, the side chain alkyl moieties of the guests leucine, methionine and valine are contained in the hydrophobic cavity of cucurbit[6]uril, but the host–guest interaction between cucurbit[6]uril and valine molecule is weak.