title: Preparation of surface imprinted material of single enantiomer of mandelic acid with a new surface imprinting technique and study on its chiral recognition and resolution properties.
abstract: A surface imprinted material of the single enantiomer of mandelic acid with high performance was successfully prepared with a new surface imprinting technique of synchronously graft-polymerizing and molecule imprinting, and its enantiomeric recognition and resolution properties were investigated. Micro-sized silica gel particles were first modified with coupling agent γ-mercaptopropyl trimethoxysilane (MPMS), obtaining the modified particles MPMS-SiO2 on which mercapto groups were introduced. A surface initiating system of -SH/BPO was constituted with the mercapto group (-SH) on MPMS-SiO2 particles and dibenzoyl peroxide (BPO) in N,N-dimethyl formamide (DMF) solution. In DMF solution, (R)-mandelic acid molecule was used as the template and the functional monomer hydroxyethyl methylacrylate (HEMA) were combined together by right of multi-site hydrogen bonds. The free radicals produced on MPMS-SiO2 particles initiate HEMA molecules around (R)-mandelic acid molecules and the crosslinking agent N,N'-Methylenebisacrylamide (MBA) to produce graft/crosslinking-polymerization. At the same time, the template (R)-mandelic acid molecules were enveloped within the thin grafted polymer layer on the surfaces of SiO2 particles, obtaining (R)-mandelic acid surface imprinted material MIP-PHEMA/SiO2. The experimental results show that MIP-PHEMA/SiO2 particles have excellent enantiomeric recognition and resolution ability. The binding capacity of MIP-PHEMA/SiO2 particles for (R)-mandelic acid reaches up to 278 mg/g. As the resolution experiment of a racemic mixture was carried out with MIP-PHEMA/SiO2 particles as solid adsorbent, relative another enantiomer, (S)-mandelic acid, the selectivity coefficient of the imprinted particles for (R)-mandelic acid is 5.02. As a consequence, the two enantiomers were well separated, and the optical purities (ee values) of the supernatant and eluant get up to 44% (corresponding to (S)-mandelic acid excess) and 85% (corresponding to (R)-mandelic acid excess), respectively.
authors.affiliation: Department of Chemical Engineering, North University of China, Taiyuan 030051, People's Republic of China. Electronic address: gaobaojiao@126.com.
authors.forename: Baojiao
authors.initials: B
authors.lastname: Gao
authors.affiliation: Department of Chemical Engineering, North University of China, Taiyuan 030051, People's Republic of China. Electronic address: chenlulu@163.com.
authors.forename: Lulu
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Chemical Engineering, North University of China, Taiyuan 030051, People's Republic of China. Electronic address: liyanbin@126.com.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Li
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000327:Adsorption; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D006860:Hydrogen Bonding; D008333:Mandelic Acids / Q000737:chemistry*; D054802:Molecular Imprinting / Q000379:methods*; D011102:Polyhydroxyethyl Methacrylate / Q000378:metabolism; D058428:Silica Gel / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000178:Acrylamides; D008333:Mandelic Acids; D011102:Polyhydroxyethyl Methacrylate; D058428:Silica Gel; D012822:Silicon Dioxide; C021221:N,N'-methylenebisacrylamide; C037938:mandelic acid
keywords: Chiral recognition; Chiral resolution; Hydroxyethyl methylacrylate; Mandelic acid; Molecule surface imprinting