Host-Guest Inclusion Complexes Of Geraniol And Nerol With Acyclic Cucurbit[N]Urils: Preparation, Characterization And Controlled Release

Two main components of rose essential oil, geraniol and nerol are highly volatile, and hardly water-soluble, which limit their further development and application in food and cosmetics industry. Host-guest inclusion complexation could be a promising strategy to address these issues. Herein, new inclusion systems of geraniol and nerol with two acyclic cucurbit[n]urils (ACBs) were fabricated, and their binding behaviors both in solution and solid states were investigated by fluorescence spectroscopy, NMR, XRD, FT-IR spectroscopy and TGA. The results confirmed the formation of host-guest inclusion complexes. The stoichiometry of the complexes was proved to be 1 : 1 by Job's plot. The possible inclusion modes were proposed by 2D-ROESY experiments. The pH-dependent release of guest molecules from the inclusion complexes has been studied via UV-Vis spectroscopy. The heat-controlled release properties of guest molecules from the solid inclusion complexes were studied via H-1 NMR spectra. The complexes featured less volatilization under low temperature, longer retention time, better water solubility and improved heat-controlled release properties. In brief, this work uncloses a new strategy to enhance the performance of essential oils and flavors/fragrances and further their application in the field of cosmetic and food industry.