Alkyl β-D-xylopyranosides are highly surface active, biodegradable surfactants that can be prepared from hemicelluloses and are of interest for use as pharmaceuticals, detergents, agrochemicals and personal care products. To gain further insights into their structure-property and structure-activity relationships, the present study synthesized a series of hydrocarbon (-C6H13 to -C16H33) and fluorocarbon (-(CH2)2C6F13) alkyl β-D-xylopyranosides in four steps from D-xylose by acylation or benzoylation, bromination, Koenigs-Knorr reaction and hydrolysis, with the benzoyl protecting group giving better yields compared to the acyl group in the Koenigs-Knorr reaction. All alkyl β-D-xylopyranosides formed thermotropic liquid crystals. The phase transition of the solid crystalline phase to a liquid crystalline phase increased linearly with the length of the hydrophobic tail. The clearing points were near constant for alkyl β-D-xylopyranosides with a hydrophobic tail ≥ 8, but occurred at a significantly lower temperature for hexyl β-D-xylopyranoside. Short and long-chain alkyl β-D-xylopyranosides displayed no cytotoxicity at concentration below their aqueous solubility limit. Hydrocarbon and fluorocarbon alkyl β-D-xylopyranosides with intermediate chain length displayed some toxicity at millimolar concentrations due to apoptosis.

Fluorocarbon-functionalized mesoporous silica is synthesized by the co-condensation of tetraalkoxysilane and fluoro-functionalized alkoxysilane precursors using a cationic fluorocarbon surfactant, C6F13C2H2NC5H5Cl (HFOPC) and C8F17C2H2NC5H5Cl (HFDePC), or a traditional hydrocarbon surfactant (C16H33N(CH3)3Br, CTAB) as templates. Fluorocarbon functionalization decreases the silica pore order, pore size, and surface area. The chain length of the fluorocarbon functional precursor and the surfactant template affects the pore order, the materials textural properties, and the fluorocarbon incorporation. Matching a fluorocarbon surfactant with a fluorocarbon functional precursor does not improve functional group incorporation; the incorporation of the perfluoro-octyl functional group is greater in CTAB-templated silica than in HFOPC-templated silica. The application of these mesoporous silica powders to fluorous separations is demonstrated using hydrocarbon and fluorocarbon-tagged anthraquinones. Dye elution through a packed column of mesoporous silica occurs in a narrower band than that for fluorocarbon-functionalized silica gel, consistent with the high fluorocarbon content and smaller pore and particle sizes of the mesoporous material.

3-Aminopropyl functionalized silica is synthesized directly using cationic fluorinated surfactants (C6F13C2H2NC5H5Cl (HFOPC) and C8F17C2H2NC5H5Cl (HFDePC)) and a hydrocarbon surfactant (C16H33N(CH3)3Br (CTAB)) as templates. The resulting 3-aminopropyl functionalized silica has a two-dimensional hexagonal pore structure, with greater order and surface area in the CTAB-templated material than the fluorinated-surfactant-templated materials. Greater amine incorporation is achieved using CTAB (1.44 mmol/g), with the least amine incorporation being observed in the HFDePC-templated material (0.92 mmol/g). The incorporation of fluorescein isothiocyanate (FITC) is used to qualitatively probe the accessibility of the amine groups. The reaction of benzaldehyde with the amine groups results in the incorporation of benzaldehyde, which is consistent with the higher accessibility of amines in fluorocarbon-surfactant-templated silica. The interaction of dry CO2 with amines results in higher CO2 sorbed in 3-aminopropyl-functionalized silica than nonfunctionalized silica, with greater amine accessibility being observed in the fluorocarbon-templated silica. The incorporation of perfluorooctyl in 3-aminopropyl-functionalized silica reduces the physisorption and CO2−amine interaction.

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