Steric and temperature control of enantiopurity of chiral mesoporous silica
2008 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, no 6, 1871-1877 p.Article in journal (Refereed) Published
To elucidate the factors and mechanisms that control the chiral mesoporous silica (CMS) formation, we employed a series of chiral amphiphilic molecules derived from nine different amino acids as templates and quantitatively investigated the effects of the substituent attached to the chiral center of amino acid upon CMS synthesis at various temperatures. The enantiomeric excess (ee) of the CMS obtained was a critical function of both the substituent’s steric bulk and the temperature, and eventually exceeded 90% ee by performing the CMS synthesis at 288 K in the presence of amphiphilic N-palmitoyl-Phe or Met. The temperature dependence study of the product’s ee not only gave the high ee’s but also enabled us to determine the differential enthalpy (Delta Delta H) and entropy (Delta Delta S) changes for antipodal CMS formation, which simultaneously increased with increasing steric bulk of the amino acid’s substituent, indicating their critical roles in determining the CMS’s enantiopurity. The present results also indicate that the CMS synthesis is a convenient tool for taking a snapshot of an average image of the dynamically fluctuating supramolecular aggregates with quantitative information (ee).
Place, publisher, year, edition, pages
2008. Vol. 112, no 6, 1871-1877 p.
IdentifiersURN: urn:nbn:se:su:diva-68207DOI: 10.1021/jp709798qISI: 000252968100024OAI: oai:DiVA.org:su-68207DiVA: diva2:472073