Host−guest inclusion systems of nicotine with acyclic cucurbit[n]urils for controlled heat releases

The thermal stability and slow release of nicotine are crucial to its shelf-life and applications. In this article, three kinds of acyclic cucurbit[n]urils (ACBs) were synthesized with cation or anion arms, benzene or naphthalene wall, aiming to handily adjust the binding ability of ACBs. The complexation behaviors and binding affinity of nicotine with ACBs in aqueous and solid state were investigated via fluorescence spectroscopy, NMR, XRD, FT−IR and DSC, which revealed the formation of host−guest inclusion systems with different stability constants (Ks). The heat-controlled release in solid state of the complexes were studied via 1H NMR spectra and TGA. Compared to nicotine, the complexes exhibited less volatility, longer retention time, better water solubility and heat-controlled release. It is our special interest to explore the binding behaviors of all kinds of ACBs with nicotine, controlled heat releases of nicotine with ACBs, which will provide a useful approach to achieve novel formulation of nicotine inclusion complexes used for products including nicotine with controlled heat releases.