A Series of Supramolecular Assemblies Triggered by Exclusion Interactions of Cucurbit[5]uril with Aromatic Amines

In this work, six novel cucurbit[5]uril-based (Q[5]) supramolecular assemblies were created with the formulas of (H 3 O)·(HPBA) 2 ·Q[5]·Cl 3 ·3H 2 O ( 1 ), (HPBA) 4 ·(Q[5]) 2 ·I 4 ·(H 2 O) 8 ( 2 ), (H 2 MDA)·Q[5]·(ZnCl 4 )·7H 2 O ( 3 ), (MDA)·(Q[5])·19H 2 O ( 4 ), (H 2 EDA)·Q[5]·(NO 3 ) 2 11H 2 O ( 5 ), and (EDA)·(Q[5])·18H 2 O ( 6 ) by introducing three different amine compounds, 4-phenylbutan-1-amine (PBA), 3,3′-methylenedianiline (MDA), and 2,2′-(ethane-1,2-diyl)dianiline (EDA), to react with Q[5] under different conditions. Structural analysis revealed that Q[5] molecules in these assemblies all interacted with each other to form supramolecular two-dimensional (2D) layers or three-dimensional (3D) networks. Although the organic amines are all protonated in the cationic form to maintain the charge balance in assemblies 1 – 3 and 5, and remain neutral in assemblies 4 and 6, all the amine groups are located on the carbonyl portals of Q[5]s through abundant hydrogen bonds to fill in the 3D Q[5] networks or assemble 2D Q[5] layers into 3D supramolecular frameworks. Furthermore, the sensing performance of assembly 1 for antibiotics was checked and the experimental results demonstrated that it could function as an efficient fluorescence ratiometric sensor for norfloxacin (NFX).