Fc-content dependence of composition, structure and degradation degree in supramolecular aggregates of polypropylene glycol, ferrocene and β-cyclodextrin

Abstract

The present work provides a framework to understand a key question of supramolecular chemistry: how the composition of supramolecular aggregates in multicomponent systems is associated with the initial stoichiometries of aggregated components. In this regard, the presentation and discussion on the importance of the content of ferrocene (Fc) in regulating the composition, structure and degradation degree of a series of ternary aggregates formed by polypropylene glycol (PPG), Fc and β-cyclodextrin (β-CD) reveal several significant findings. First, the higher the initial concentration of Fc, the higher the Fc-content in the aggregates precipitated, the higher the complexation ratio (CR) of β-CD to Fc, the lower the CR of β-CD to PPG. Not only does this significant finding open a window to the design and synthesis of multicomponent aggregates, but also it provides us with a new insight on our understanding of supramolecular stoichiometry. Second, the influence of Fc-content dependences was further supported by differences in microstructure and electronic structure of the aggregates. Third, a positive effect of Fc in improving degradation degrees of organic oligomers aggregated was demonstrated by the facts that the degradation degrees strongly depended on the amount of Fc, and that even in the presence of a little amount of Fc, the positive effect was still apparent. Finally, a further research indicates that the Fe component plays a key role in dominating the thermal degradation process of aggregates compared to the cyclopentadienyl rings. Taken together, these observations provide a scientific basis for the development of new multicomponent aggregates.