Self-assembled thermoreversible gels of nonpolar liquids by racemic propargylic alcohols with fluorinated and nonfluorinated aromatic rings

The synthesis and colloidal study of a new class of low molecular weight organogelators is reported. Racemic propargylic alcohols with perfluoroaryl and nonfluorinated aryl rings are capable of forming gels in alkane liquids and/or silicone oil. A full colloidal characterization of alkane gels prepared from (RIS)-1-pentafluorophenyl-3-phenylprop2-yn- 1-ol [(RIS)-1] was conducted, including both structural [optical microscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), attenuated total reflectance infrared spectroscopy (ATR-IR)] and thermal stability [differential scanning calorimetry (DSC)] studies. A model of the organization of gelator molecules within gel fibers has been proposed primarily based on the correlation of diffraction data for the powder XRD pattern of a get and a simulated powder pattern from a sublimed crystal of the gelator. Furthermore, structural requirements for propargylic alcohol gelators were investigated by subjecting derivatives with modified structures to gelation tests. An enantiomerically enriched sample [(R)-1, 83% ee] fails to entrap the solvent under conditions where the racemate successfully forms a gel. The remaining racemic derivatives (with p-alkoxy or p-alkyl substituents on the nonfluorinated arene) form gels or partial gels in silicone oil and in some alkane preparations.