Synthesis Of Novel Low Molecular Weight Gelators And Study Of Their Gel Properties And Mechanisms

Benzoyl thiourea derivatives and2,5-disubstituted1,3,4-oxadiazoles have beensynthesized as low molecular weight gelators（LMWG） in this paper, and their gelationproperties and the mechanisms of gelation process have also been studied.Benzoyl thiourea derivatives were synthesized from methyl4-hydroxybenzoate and4-Nitrophenol. The structures were confirmed by¹H NMR and¹³C NMR. This kindof compounds showed excellent gelation properties because of the wide variety oforganic solvents in which gelator can be formed and the low minimum gelationconcentration （5mg/mL）. The photographs from scanning electron microscopy（SEM）showed clear fibrous network structures. Through the studies of the IR, UV,¹H NMRand single-crystal X-ray diffraction, we can come to the conclusion that theintermolecular hydrogen bond and van der Waals interaction are the main drivingforce for gelation. The results of X-ray diffraction （XRD） suggested that the dry gelshad a layer structure. The gel-sol phase transition process could be selectivelycontrolled by interaction with F-（TBAF） and proton solvent （CH3OH）2,5-Disubstituted1,3,4-oxadiazoles were synthesized from methy4-hydroxyben-zoate and4-cyanophenol. The structures were also confirmed by¹H NMR and¹³CNMR. This series of compounds can form gelator in most alcohols, amines and arylhydrocarbons. The result of X-ray diffraction （XRD） suggested that the gels had thelamellar structures. The results of SEM showed clear fibers. UV and IR spectrumrevealed that π-π interaction and van der Waals interaction were the main drivingforce in the process of gelation.