l- and d-Proline Adsorption by Chiral Ordered Mesoporous Silica

Abstract

Chiral ordered mesoporous silica (COMS) was synthesized in the presence of amino acid proline by combining tetraethyl orthosilicate and quaternized aminosilane silica sources. The as-prepared materials were activated by calcination or microwave chemical extraction to remove the organic templates. The powder X-ray diffraction and N2 adsorption characterization revealed in COMS the structural and textural features of MCM-41-type silica. The chirality of the material was disclosed by mixed and separate l- and d-proline adsorption on the COMS prepared with l-proline (l-Pro-COMS) and d-proline (d-Pro-COMS). It was found that the maximum l-proline and d-proline adsorption capacities on l-Pro-COMS were ca. 2.3 and 0.6 mmol/g, respectively, while the adsorption of d-proline was higher than that of l-proline on d-Pro-COMS. Finally, both activation routes yielded enantioselective silicas able to separate proline racemate.

Immobilization of L-Lysine on Zeolite 4A as an Organic-Inorganic Composite Basic Catalyst for Synthesis of α,β-Unsaturated Carbonyl Compounds under Mild Conditions

“…The adsorption behavior of amino acids on the surfaces of materials such as hydroxyapatite, zirconium phosphate modified silica, silica-gels, activated carbon and zeolite has been investigated. [10][11][12][13][14][15][16] Although many cases of successful immobilization using inorganic porous materials have been reported, most of the research published only uses standard activity assays to monitor the catalytic performance. In other words, the application of amino acids adsorbed on inorganic supports in terms of catalytic purposes has received very little attention.…”

Chiral Mesoporous Silica Materials: A Review on Synthetic Strategies and Applications

“…As proved by circular dichroism (CD) spectroscopy, monodispersed CMS spheres with chiral pores showed the asymmetric preferential adsorption of alanine with a chiral selectivity factor of 3.15 [ 74 ]. Interestingly, it was found that the adsorption of d -proline by CMS synthesized with d -proline was higher than that of l -proline, while the adsorption of l -proline by CMS synthesized with l -proline was significantly higher than that of d -proline [ 75 ]. This adsorption difference could be ascribed to the imprinting left by the amino acid during the preparation process.…”

Cooperative formation of porous silica and peptides on the prebiotic Earth

“…The synthesis of chiral mesoporous silica which contains hexagonally ordered chiral channels transcribed from the organic SDA was first reported by Che et al (25). Chiral ordered mesoporous silica was synthesized in the presence of the amino acid proline (26). Pure right-and left-handed chiral mesoporous silica and organosilica phases were produced using a chiral anionic surfactant in the presence of a chiral amino acid (L-or D-arginine) (27).…”