A new gelator 3-hydroxy-2-［N-(carboxypropyl carbonyl)amino］ pyridine(defined as SWG) was synthesized from 3-hydroxy2-amino pyridine and glutaric anhydride by a simple procedure.The gelator structure was confirmed by IR

1H-NMR and elemental analysis.The characteristic peaks of 2576 cm-1and 1906 cm-1 in the IR spectrum indicated the formation of hydrogen bonds between carboxylic acid and pyridyl groups.Supramolecular hydrogels were formed within 1 min via cooling the 1.5 wt% SWG aqueous solution in an ultrasonic vessel at 20℃ under different ultrasonic powers.However

only macroscopic crystals were formed in the same solution without ultrasonic treatment.The gels were analyzed by SEM

DSC and geltosol dissociation temperature(Tgel) measurements.The results indicated that SWG molecules assembled into aggregating fibers during the gelating process.With increasing the ultrasonic powers from 200 W to 500 W

the fiber width decreased from 8 μm to 2 μm

the network density increased

the freezing water content increased from 86.5% to 96.1%

and the Tgel increased from 60℃ to 70℃.Therefore the ultrasonic treatment is effective in controlling gel structures and properties.Furthermore

the gel with larger fiber

more compact fibrillar network and higher Tgel were obtained as increasing the gelator concentration from 1 wt% to 2.5 wt%.The X-ray powder diffraction (XRD) analysis of xerogel and powder samples of SWG indicated that the molecules assembled in a preferred direction during the gelating process.These results are important for understanding the gelating mechanism and designing new hydrogels.