Stereoselective Formation of a 2 : 1 Molecular Complex between α-Cyclodextrin and carbazole-Viologen Linked Compound with a Long Alkyl Chain as the Spacer

Abstract
Analysis of 1H NMR spectra revealed a novel mode of complexation between α-cyclodextrin (CD) and a carbazole-viologen linked compound with 16 methylene units in the spacer. The complexation afforded a stable rotaxane-type CD complex, where two α-CDs encased the spacer chain. NOE experiments confirmed selective formation of unique isomer among four possible orientations of the encasing α-CD.