Promotion effects of optical antipodes on the formation of helical fibrils: chiral perfluorinated gelators

Abstract

A chiral gelator, RR- or SS-N,N'-diperfluorooctanoyl-1,2-diaminocyclohexane, gelated racemic 2-butanol. The gel was most stable at the racemic mixture, its stability lowered with the increase in the optical purity of the gelator. Notably, characteristic helically coiled fibrils were formed in the narrow region of enantiomer excess (ee = 0.2-0.4). Promotion effects of the antipodal enantiomers are proposed.

Helical Inversion of Gel Fibrils by Elongation of Perfluoroalkyl Chains as Studied by Vibrational Circular Dichroism

“…SEM observation of fibril structures. A series of chiral low‐molecular weight gelators were synthesized (Chart ) . The compounds were identified by 1 H NMR, mass spectra, 19 F NMR, and differential scanning calorimetry .…”

“…Recently, extensive work has been performed to develop gelators with perfluoroalkyl chains. A basic concept was formed on the interplay of their dual characters, hydrophobicity and fluorophilicity . From the practical point of view, gelators with perfluoroalkyl chains are a promising application to gelate fluorous solvents .…”

“…It has been demonstrated that the elongation of perfluoroalkyl chains by ‐CF 2 units from n = 6 to 8 resulted in a drastic change of gelation behavior. For example, enantiopure CF7 formed a gel acetonitrile, while enantiopure CF8 was precipitated as a crystalline from the same solvent . Furthermore, in the case of CF9 , both chiral and racemic gelated the acetonitrile solvent.…”

Supramolecular Polymers as Surface Coatings: Rapid Fabrication of Healable Superhydrophobic and Slippery Surfaces

“…[ 24 ] It forms a stable gel in acetonitrile at 1 mg mL −1 [ 24 ] confi rming its ability to polymerize through hydrogen bonding. It is soluble in diethyl ether (up to 25 mg mL −1 ) and acetone (up to 20 mg mL −1 ).…”

“…IR spectroscopy reveals the presence of amide-amide hydrogen bonding ( Figure S6, Supporting Information) in the dried fi lm with wavenumbers of the characteristic vibrations being very close to those observed in the gel state of CF7 . [ 24 ] The formation of the gel fi ber network on the surface during fi lm preparation is confi rmed by scanning electron microscopy (SEM) ( Figure 2 a) and transmission electron microscopy (TEM) ( Figure S7, Supporting Information). A three-dimensional entangled fi brous network of fi ber bundles with diameters of 1 to 4 µm and lengths up to several hundreds of micrometers is formed.…”