Spectrophotometric Study of Selective Binding Behaviors of Dye Molecules by Pyridine- and Bipyridine-Modified β-Cyclodextrin Derivatives with a Functional Tether in Aqueous Solution

Abstract

Four β-cyclodextrin (β-CD) derivatives bearing pyridine or bipyridine linkers, i.e., mono[6-(3-pyridinecarboxamide)ethyleneamino-6-deoxy]-β-CD (2), mono[6-(4-pyridinecarboxamide)ethyleneamino-6-deoxy]-β-CD (3), N,N‘-bis(2-aminoethyl)-2,2‘-bipyridine-4,4‘-dicarboxamide-bridged bis(6-amino-6-deoxy-β-CD) (4), N,N‘-bis(2-aminoethyl)-2,2‘-bipyridine-3,3‘-dicarboxamide-bridged bis(6-amino-6-deoxy-β-CD) (5), and their copper(II) complexes (6 and 7) were selected as molecular receptors to explore the conformation−function relationship of oligo(β-CD)s. The original conformations of hosts 4−7 and their inclusion complexation behaviors with some guest molecules, i.e., ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 6-(p-toludino)-2-naphthalenesulfonate (TNS), and rhodamine B (RhB), were comprehensively investigated by means of UV−vis, 2D NMR, and fluorescence spectroscopy. The results indicated that these oligo(β-CD)s, especially bis(β-CD) 5 and its copper(II) complex 7, exhibited the significantly enhanced ...