Molecular Necklaces Containing Reporter Molecules

Abstract

Linear poly(alkylene oxide)s and cyclodextrins (CDs) can be used in the creation of supramolecular rotaxane-type structures. Complexes of these compounds represent molecular necklaces—structures where many cyclodextrin molecules are threaded on a polymer chain. Their stability is governed by the correspondence between the cyclodextrin cavity size and the diameter of a polymer guest. Thus, poly(ethylene oxide) (PEO) gives complexes with six-membered α-CD, and poly(propylene oxide) (PPO) gives complexes with seven-membered β-CD [1]. γ-CD can form molecular necklaces with 2 chains of PEO or 1 chain of PPO [1, 2]. Following the concept of spatial correspondence, one can predict the occurrence of ternary complexes in which molecular necklaces include low-molecular guest molecules. For example, these complexes can be obtained in the system PEO-β-CD-aromatic compound.