Synthesis, Self-Assembling Properties, and Atom Transfer Radical Polymerization of an Alkylated L-Phenylalanine-Derived Monomeric Organogel from Silica: A New Approach To Prepare Packing Materials for High-Performance Liquid Chromatography
✍ Scribed by M. Mizanur Rahman; Miklós Czaun; Makoto Takafuji; Hirotaka Ihara
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 438 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0947-6539
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The monomer N′‐octadecyl‐N^α^‐(4‐vinyl)‐benzoyl‐L‐phenylalanineamide (4) based on L‐phenylalanine has been simply but effectively synthesized, and its self‐assembling properties have been investigated. FTIR and a variable‐temperature ^1^H NMR spectroscopic investigation demonstrated that the aggregation of compound 4 in various organic solvents is due to the formation of intermolecular hydrogen bonds among the amide moieties. UV/Vis measurements indicated that the multiple π–π interactions of the phenyl groups also contribute to the self‐assembly. As was observed by ^13^C cross‐polarization magic‐angle spinning (CP/MAS) NMR and variable‐temperature ^1^H NMR measurements, the ordered alkyl chains also played an important role in the molecular aggregation by van der Waals interactions. Compound 4 was polymerized by surface‐initiated atom transfer radical polymerization from porous silica gel to prepare a packing material for HPLC. The results of thermogravimetric analysis showed that a relatively large amount of polymer was grafted onto the silica surface. The organic phase on silica was in a noncrystalline solid form in which the long alkyl chain exists in a less‐ordered gauche conformation. Analysis of chromatographic performance for polyaromatic hydrocarbon samples showed higher selectivity than conventional reversed‐phase HPLC packing materials.