摘要
A series of novel and simple ligands based on a biscarboxyl-functionalized benzimidazole derivative were synthesized.The experiments showed that the ligand L2 as a low molecular weight(LMW) hydrogelator could form stable metallo-hydrogels in the presence of up to 0.3 equiv.of lead ions.The metallo-hydrogels were characterized using powder X-ray diffraction,scanning electron microscopy(SEM),and Fourier transform infrared(FT-IR) spectroscopic techniques.When the molar ratio of L2:Pb2+ was in the range of 1:0.3 to 1:0.5 a translucent gel was produced.When the L2:Pb2+ molar ratio was higher than 1:0.5 the resulting gel tended to be opaque.The morphologies of these metallo-hydrogels were L2/Pb ratio dependent,ranging from worm-like to rod-shaped and nanofibrous.The FT-IR and X-ray diffraction(XRD) studies revealed that L2-Pb complexation was the main driving force for the formation of the metallo-hydrogels.In addition,these metallo-hydrogels exhibited outstanding thermostability and thermoreversibility,and displayed a reversible sol-gel transition induced by changes in pH and EDTA concentration.Importantly,ligand L2 showed an excellent capacity for the removal of Pb 2+ in aqueous solution through the formation of metallo-hydrogels.At a L2:Pb molar ratio of 1:0.5 and below,the concentration of residual Pb2+ was as low as 7.6×10-5 mol/L in aqueous solution,and the removal ratio was as high as 95.4%.These results demonstrate that multi-channel responsive smart metallo-hydrogels have the potential to be widely applied in materials science,and might provide the basis for lead pollution capture and removal.
A series of novel and simple ligands based on a biscarboxyl-functionalized benzimidazole derivative were synthesized. The experiments showed that the ligand L2 as a low molecular weight （LMW） hydrogelator could form stable metallo-hydrogels in the presence of up to 0.3 equiv, of lead ions. The metallo-hydrogels were characterized using powder X-ray diffraction, scan- ning electron microscopy （SEM）, and Fourier transform infrared （FT-IR） spectroscopic techniques. When the molar ratio of L2：Pb2＋ was in the range of 1：0.3 to 1：0.5 a translucent gel was produced. When the L2：Pb2＋ molar ratio was higher than 1：0.5 the resulting gel tended to be opaque. The morphologies of these metallo-hydrogels were L2/Pb ratio dependent, ranging from worm-like to rod-shaped and nanofibrous. The FT-IR and X-ray diffraction （XRD） studies revealed that L2-Pb complexation was the main driving force for the formation of the metallo-hydrogels. In addition, these metallo-hydrogels exhibited out- standing thermostability and thermoreversibility, and displayed a reversible sol-gel transition induced by changes in pH and EDTA concentration. Importantly, ligand L2 showed an excellent capacity for the removal of Pb2＋ in aqueous solution through the formation of metallo-hydrogels. At a L2：Pb molar ratio of 1：0.5 and below, the concentration of residual Pb2＋ was as low as 7.6 ×10^5 mol/L in aqueous solution, and the removal ratio was as high as 95.4%. These results demonstrate that multi-channel responsive smart metallo-hydrogels have the potential to be widely applied in materials science, and might provide the basis for lead pollution capture and removal.
基金
supported by the National Natural Science Foundation of China(21064006 and 21161018)
the Natural Science Foundation of Gansu Province(1010RJZA018)
the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(IRT1177)
