title: Evidence of intercolumnar π-π stacking interactions in amino-acid-based low-molecular-weight organogels.
abstract: A comparative IR and NMR study of two low-molecular-weight organogels (LMWGs) based on aminoacid derivatives let us point out the hierarchy of the gelation assembly process. Different association states of corresponding organogelator molecules can be observed leading to the supramolecular organization of gel. A first hydrogen bond network of gelators leads to the formation of "head-to-tail" stacking-up, which can be assembled afterward one to the other by π-π stacking interactions. These small supramolecular aggregates (incipient precursor) are still visible in NMR spectra, and they represent, for example, 36% of the total amount of gelator in the case of the L-phenylalanine derivative (gelator 1) at 1 wt % in toluene. Finally, in the last step, the incipient precursor tends to form the expected 3D fibrillar network responsible for the gelation phenomenon. Temperature-dependent IR and NMR experiments allowed us to identify these different states clearly.
authors.affiliation: Laboratoire de Chimie-Physique Macromoléculaire, UMR CNRS-INPL 7568, Nancy-Université, ENSIC, 1 rue Grandville, BP 20451, 54001 Nancy Cedex, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Allix
authors.forename: Pasquale
authors.initials: P
authors.lastname: Curcio
authors.forename: Quoc Nghi
authors.initials: QN
authors.lastname: Pham
authors.forename: Guillaume
authors.initials: G
authors.lastname: Pickaert
authors.forename: Brigitte
authors.initials: B
authors.lastname: Jamart-Grégoire
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D005782:Gels; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D000596:Amino Acids; D005782:Gels