N-stearoyl amino acid derivatives: potent biomimetic hydro/organogelators as templates for preparation of gold nanoparticles

Abstract

New potent N-(2-aminoethyl)-α-[(1-oxoheptadecyl)amino]acetamide derivative gelators were synthesized and their self-assembly in various common solvents was examined. These compounds exhibit high gelation ability in many organic solvents, such as toluene or acetonitrile, with a lower critical gelation concentration of 0.15 wt.% in some cases. The organogels were analyzed by (1)H nuclear magnetic resonance (NMR) and Fourier transform-infrared (FT-IR) spectroscopies, and their phase transition temperatures (T(gel)) were determined using differential scanning calorimetry (DSC). The homogeneity of the gel networks was observed using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) and a lamellar structure was confirmed by X-ray diffraction (XRD) analysis. A correlation between the more stable conformations of N-acyl glutamine derivative determined by molecular modeling and the gelation behavior afforded evidence for the influence of the dimethylene side chain on the gelation ability. The organogels were employed as templates for the in situ preparation of stable gold nanoparticles (GNPs) using different reduction methods of HAuCl(4) dispersed in the gel matrix, and the resulting GNPs solutions were studied using UV-Visible absorption and TEM.