Highly Thermally Resistant Bisamide Gelators as Pharmaceutical Crystallization Media.

Three simple bisamide derivatives (, and ) with different structural modifications were synthesized with easy synthetic procedures in order to test their gel behaviour. The outcomes showed that hydrogen bonding was essential in gel formation; for this reason, only provided satisfactory gels. The presence of methoxy groups in and the alkyl chains in hindered the hydrogen bonding between N-H and C=O that occurred . In addition, provided thermally and mechanical stable gels, as confirmed with T and rheology experiments. The gels of were also responsive under pH stimuli and were employed as a vehicle for drug crystallization, causing a change in polymorphism in the presence of flufenamic acid and therefore providing the most thermodynamically stable form III compared with metastable form IV obtained from solution crystallization.