title: Enantioselective separation using chiral mesoporous spherical silica prepared by templating of chiral block copolymers.
abstract: In this work, we synthesized chiral mesoporous silica (CMS) spheres, which can be used as a potential candidate for chiral separation. The CMS spheres with controllable pore sizes (of 2-3 nm) and high surface areas of ca. 614 m(2) g(-1) were synthesized by chiral templating with chiral block copolymers based on poly(ethylene oxide) and dl-glutamic acid [PEO(113)-b-(GluA)(10)]. The ordered structure of the chiral mesopores was characterized by high-resolution transmission electron microscopy, and the average pore diameters of chiral mesopores were estimated from the nitrogen adsorption-desorption measurements. The enantioselectivity properties and chiral resolution kinetics of the mesopores of silica spheres, after extraction of chiral polymers of PEO(113)-b-(l/d-GluA)(10), were scrutinized using a racemic solution of valine and measuring the circular dichroism and optical polarimetery. A chiral selectivity factor of 5.22 was found with a specific enantiomer of valine adsorbed preferably. These results raise the new possibilities of CMS spheres for enantiomeric separation and other enantioselective applications.
authors.affiliation: Kanbar Laboratory for Nanomaterials and Institute of Nanotechnology, Department of Chemistry, Bar-Ilan University, Ramat Gan 52900, Israel.
authors.forename: Pradip
authors.initials: P
authors.lastname: Paik
authors.forename: Aharon
authors.initials: A
authors.lastname: Gedanken
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Mastai
mesh_terms: D000327:Adsorption; D002621:Chemistry / Q000379:methods; D002625:Chemistry, Organic / Q000295:instrumentation / Q000379:methods*; D002942:Circular Dichroism; D004952:Esters / Q000737:chemistry; D018698:Glutamic Acid / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D055095:Optics and Photonics; D011108:Polymers / Q000737:chemistry* / Q000302:isolation & purification; D012822:Silicon Dioxide / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D004952:Esters; D011108:Polymers; D018698:Glutamic Acid; D012822:Silicon Dioxide