title: Effects of substitution groups of glutamide-derived molecular gels on molecular shape recognition.
abstract: We have reported that self-assembling glutamide lipid-grafted porous silica particles show high selectivity towards polycyclic aromatic hydrocarbons (PAHs) and bio-molecules. This enhancement of molecular recognition is brought about by the formation of a highly ordered structure in the glutamide lipid through intermolecular hydrogen bonding. To utilise, for selective separations, the highly oriented structure of glutamide lipids on the silica surface, in this study, we synthesised four glutamide lipids with different substitution groups and studied the separation behaviours of the glutamide lipid-grafted porous silica particles as reversed phase high-performance liquid chromatography (RP-HPLC) stationary phases. According to the HPLC studies, the functional group substitutions and the spacer group connecting the glutamide moiety and silica surface had a noticeable effect on the retention behaviours. Particularly, glutamide lipids with a long spacer group (C10) showed a higher selectivity towards positional (o-/m-/p-terphenyl) and geometrical (cis-/trans-stilbene) isomers. Differential scanning calorimetric and Fourier transform infrared spectroscopic studies suggested that the long spacer group induced the assembled structure of the glutamide lipid on the silica surface. Interestingly, the glutamide lipids with dodecyl groups and benzyl groups showed reverse elution orders towards the length to breadth ratio of PAHs.
authors.affiliation: Department of Applied Chemistry and Biochemistry, Kumamoto University, Kumamoto, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Noguchi
authors.affiliation: Department of Applied Chemistry and Biochemistry, Kumamoto University, Kumamoto, Japan.
authors.forename: Tiraporn
authors.initials: T
authors.lastname: Charoenraks
authors.affiliation: Department of Applied Chemistry and Biochemistry, Kumamoto University, Kumamoto, Japan. Electronic address: takafuji@kumamoto-u.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Takafuji
authors.affiliation: Department of Nanoscience and Technology, Kumamoto University, Kumamoto, Japan; Kumamoto Institute for Photo-electro Organics(PHOENICS), Kumamoto, Japan. Electronic address: ihara@kumamoto-u.ac.jp.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ihara
mesh_terms: D002762:Cholecalciferol / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D056148:Chromatography, Reverse-Phase / Q000379:methods; D004872:Ergocalciferols / Q000032:analysis; D005782:Gels; D005971:Glutamates / Q000737:chemistry*; D007536:Isomerism; D008055:Lipids / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship; D024505:Tocopherols / Q000032:analysis
chemical_list: D004872:Ergocalciferols; D005782:Gels; D005971:Glutamates; D008055:Lipids; D011084:Polycyclic Aromatic Hydrocarbons; D002762:Cholecalciferol; D012822:Silicon Dioxide; D024505:Tocopherols
keywords: Molecular gel; Polycyclic aromatic hydrocarbons; Stationary phases, Liquid chromatography; π–π interaction