King's College London

A biomimicking approach for the selective capture of dimethylcyclosiloxanes was developed. Inclusion complexes between cyclodextrins (CDs) and cyclosiloxanes were isolated and subsequently treated with toluene-2,4-diisocyanate (TDI) in DMSO to afford molecularly imprinted cyclodextrin (MICD) polymers. Following removal of the siloxane-based templates, the imprinted biomimetic polymers were characterized via scanning electron microscopy (SEM), cross-polarization magic angle spinning (CP-MAS) NMR and elemental analysis. Substrate affinity and selectivity were evaluated via equilibrium batch-rebinding assays and quantitative gas-chromatographic analysis. The imprinting effect was assessed by comparing the binding of the synthetic receptors with blank (non-imprinted) polymers. Adsorption isotherms were measured and data fitted using several mathematical models and the dissociation constants (Kd) and the binding site densities (Bmax) were calculated. The study is believed to have delivered the first case of an artificial receptor for an organosilicon substrate, opening a new way for separation and purification in silicon chemistry.