An artificial organosilicon receptor

Abstract

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 (K_d) and the binding site densities (B_max) 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.