title: General approach to low-molecular-weight metallogelators via the coordination-induced gelation of an L-glutamate-based lipid.
abstract: A twin-tailed glutamate-based lipid with a pyridine headgroup was prepared in good yield using standard amide coupling and protection/deprotection chemistry. The resulting Lewis basic lipid gels a wide array of hydrocarbon solvents at a critical gelation concentration (C(g)) of 0.3 wt %. The gelation of more polar solvents, such as ethanol, THF, dichloromethane, and chloroform, occurs with a C(g) of between 2 and 5 wt %, demonstrating the importance of hydrogen bonding interactions in gel formation. The importance of hydrogen bonding in this system was also demonstrated by IR observation of the amide bands, which show a substantial shift upon gelation. Solutions of this new organogelator with concentrations below C(g) rapidly form gels upon the introduction of a wide variety of metal salts or complexes, providing a convenient general method for the preparation of metallogelators. Spectroscopic evidence suggests that the enhanced gelation seen in the metal-containing systems can be explained by a cross-linking of gel fibril aggregates similar to those formed by the unmetalated gelator.
authors.affiliation: Department of Chemistry, The University of the South, 735 University Avenue, Sewanee, Tennessee 37383, United States. rbachman@sewanee.edu
authors.forename: Robert E
authors.initials: RE
authors.lastname: Bachman
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Zucchero
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Robinson
mesh_terms: D005782:Gels; D018698:Glutamic Acid / Q000737:chemistry*; D006860:Hydrogen Bonding; D008055:Lipids / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D013055:Spectrophotometry, Infrared
chemical_list: D005782:Gels; D008055:Lipids; D018698:Glutamic Acid