Salt complexes of two-component N-acylamino acid diastereoisomers: self-assembly studies and modulation of gelation abilities

The self-assemblies and gelation of various organic solvents by salt complexes of two-component N-acylamino acid diastereoisomers are described. The potent organogelator, N-(2-aminoethyl)-alpha-[-(1-oxoheptadecyl)amino]phenyl) propanamide, was mixed with various N-acyl leucines having different fatty alkyl chain lengths at a ratio of 1:1. In some cases, their complexation resulted in modulations of the current gelation abilities. When the L-form of the organogelator was used for mixing, the gelation ability appeared to be independent of the hydrophobic nature of the N-acyl leucine. This is not observed when the racemate form of the organogelator was used. Moreover, a minimum gelation concentration (MGC) in aromatic solvents as well as improvements of the gelation ability such as formation of a robust hydrogel in water, gelation of the R-propylene carbonate, and unexpected gelation of pyridine were observed. The supramolecular gels were analyzed by Fourier Transform-Infrared (FT-IR), H-1 nuclear magnetic resonance (NMR) spectroscopies, and rheology analysis. The phase transition temperatures (Tg-s) were determined using differential scanning calorimetry (DSC). Homogeneity of the gel networks was observed by field emission scanning microscopy (FE-SEM) and transmission electron microscopy (TEM). The lamella structure was confirmed by X-ray diffraction (XRD). (C) 2012 Elsevier Ltd. All rights reserved.