A favorable, narrow, δ(h) Hansen-parameter domain for gelation of low-molecular-weight amino acid derivatives.
In recent years, the design of new low-molecular-weight gelators (LMWGs) has attracted considerable attention because of the interesting supramolecular architectures as well as industrial applications. In this context, the role of the organic solvent in determining the organogelation behavior is a central question. Herein we report the results of a systematic study of the organogelation behavior of amino acid derivatives in a wide range of solvents to establish a relationship between the nature of the solvent and the formation of the gel. We highlight that the majority of the gelified solvents are aromatic, except for carbon tetrachloride and tetrachloroethylene. In addition, different parameters related to the nature of the solvent were considered and their influence on the physical properties of gelation was evaluated. The hydrogen-bonding Hansen parameter (δ(h)) allows us to draw a narrow favorable δ(h) domain for gelation in the range of 0.2-1.4 (cal cm(-3))(1/2). Furthermore, a general increase of the Hildebrand parameter (δ) leads to the formation of poor gels (small gelation numbers, GNs) in aromatic solvents. Scanning electron microscopy (SEM) revealed that the gels prepared from (l)-phenylalanine and (l)-leucine derivatives in different solvents are composed of an entangled 3D fibrillar network, the diameter of which is only slightly influenced by the nature of the solvent.
Laboratoire de Chimie-Physique Macromoléculaire, UMR CNRS-INPL 7568, Nancy-Université, ENSIC, 1 rue Grandville, BP 20451, 54001 Nancy Cedex, France.
Pasquale
P
Curcio
Florent
F
Allix
Guillaume
G
Pickaert
Brigitte
B
Jamart-Grégoire
D000596:Amino Acids / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006860:Hydrogen Bonding; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D012997:Solvents / Q000737:chemistry*
D000596:Amino Acids; D005782:Gels; D006571:Heterocyclic Compounds; D012997:Solvents