Construction and fluorescence sensing performance of cucurbit[5]uril-based supramolecular assemblies incorporating amino-containing sulfonate ligand as structure inducer

Abstract

In this work, an amino-containing sulfonate ligand, sodium 6-amino-7-sulfonaphthalene-2-sulfonate (NaHANDS), was employed as the structure inducer to react with cucurbit[5]uril (Q[5]) and alkali metals to afford four novel Q[5]-based suparmolecular assemblies with the formula of [Na4(H2O)2(Q[5])2(ANDS)2]·22H2O (1), [K2(H2O)3(Q[5])]·ANDS·7H2O (2), [Rb2(H2O)3(Q[5])]·ANDS·8H2O (3) and [Cs2(H2O)2(Q[5])(ANDS)]·12H2O (4). Crystal structure determination manifested that the alkali metal cations in these four assemblies all coordinate with Q[5] molecules but formed simple complexes for 1/2 and coordination chains for 3/4 due to the large radius of Rb+ and Cs+ than Na+ and K+. Moreover, although the completely deprotonated ligands ANDS2- merely formed coordination bonds with Na+ or Cs+ in assemblies 1 and 4, all of them generate various noncovalent interactions with the outer surface of Q[5] to afford the final supramolecular architecture. Furthermore, the fluorescence sensing capacity of assembly 2 towards antibiotics was chosen as an example to be explored and the results indicated that assembly 2 can selectively detect chloramphenicol (CAP) with high sensitivity and low detection limit.