Surface molecularly imprinted material for enantiomeric resolution of ibuprofen: Preparation and study on chiral recognition and resolution property

Abstract

ABSTRACTThe surface imprinted material of one single enantiomer of ibuprofen ((S)-ibuprofen) was successfully prepared using the novel surface imprinting technique of synchronously graft/crosslinking-polymerizing and molecule imprinting. Micron sized-silica gel particles as matrix were first modified with coupling agent γ-mercaptopropyl trimethoxysilane (MPMS), obtaining MPMS-SiO2 particles, on which there was a great deal of mercapto group (‒SH). Hydroxyethyl methylacrylate (HEMA) as functional monomer and dibenzoyl peroxide (BPO) as initiator were dissolved into 1,2-dichloroethane (DCE), and HEMA molecules are automatically combined around (S)-ibuprofen molecules by right of multi-site hydrogen bonds, forming self-assembly complex. A surface-initiating system of ‒SH/BPO was constituted at the interface between MPMS-SiO2 particles and DCE solution. The free radicals produced on the surfaces of MPMS-SiO2 particles initiated HEMA molecules around (S)-ibuprofen molecules to produce graft/crosslinking-polymerization on the surfaces of SiO2 particles. At the same time, (S)-ibuprofen molecules were wrapped in the cross-linked networks so that the surface-imprinting of (S)-ibuprofen was realized, forming (S)-ibuprofen surface imprinted particles ((S)-IBU-SIP). The enantiomeric recognition and resolution properties of (S)-IBU-SIP particles were investigated. The experimental results show that (S)-IBU-SIP particles have excellent enantiodiscrimination property and enantioseparation ability. The binding capacity of (S)-IBU-SIP particles for (S)-ibuprofen gets up to 177 mg g−1, and the selectivity coefficient of (S)-IBU-SIP particles for (S)-ibuprofen relative to (R)-ibuprofen is 5.03. For the ibuprofen raceme solution, after solid phase extraction by (S)-IBU-SIP particles, the optical purity (ee value of (S)-ibuprofen) of the eluent reaches up to 82.5%, whereas the optical purity (ee value of (R)-ibuprofen) of the supernatant is 44.2%.