Fluorine Effect in the Gelation Ability of Low Molecular Weight Gelators.

The three gelators presented in this work (Boc-D-Phe-L-Oxd-OH , Boc-D-FPhe-L-Oxd-OH and Boc-D-FPhe-L-Oxd-OH ) share the same scaffold and differ in the number of fluorine atoms linked to the aromatic ring of phenylalanine. They have been applied to the preparation of gels in 0.5% or 1.0% / concentration, using three methodologies: solvent switch, pH change and calcium ions addition. The general trend is an increased tendency to form structured materials from to and . This property ends up in the formation of stronger materials when fluorine atoms are present. Some samples, generally formed by or in 0.5% / concentration, show high transparency but low mechanical properties. Two gels, both containing fluorine atoms, show increased stiffness coupled with high transparency. The biocompatibility of the gelators was assessed exposing them to fibroblast cells and demonstrated that and are not toxic to cells even in high concentration, while is not toxic to cells only in a low concentration. In conclusion, the presence of even only one fluorine atom improves all the gelators properties: the gelation ability of the compound, the rheological properties and the transparency of the final materials and the gelator biocompatibility.