Host-guest interaction is one of the defining concepts of supramolecular chemistry which describes an idea of molecular recognition and interactions through non-covalent bonding between two or more molecules or ions. Based on the specific recognition of host molecules towards guest molecules, host-guest chemistry has been widely studied for drug carriers, dye encapsulation, nanoreactors, recovery of catalysts, and etc. Cyclodextrin (CD) is one of a well-known host molecule, and its hydrophobic cavity provides a strong binding interaction with azo benzenes and adamantyl group via van der Waals force in water solution. Using this property, we have newly developed a highly recoverable Hoveyda-Grubbs 2<sup>nd</sup> generation catalyst bearing extended ethylene glycols and adamantyl group on NHC ligand. In particular, extended ethylene glycol group provides a highly water soluble property for a homogenous catalytic reaction in water as well as a recovery of catalysts from organic solution by extraction with water. The adamantyl group combines with β-CD in aqueous solution, and this host-guest complex leads an efficient heterogeneous recovery of entire ruthenium catalyst after homogeneous reaction.

Recycle of PEG-bound homogeneous NHC-Ru catalyst via host-guest interaction in aqueous media

254th National Meeting (2017)

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