Construction Of Hydrogen Bond Networks In Multi-Tunnel Meatal-Organic Framework-based Hybrid Materials With Proton Conducting Performance

Metal-organic frameworks(MOFs)have been highlighted in the field of proton conduction owing to their infinite and well-organized cage construction and highly designable nature to construct desired proton-conducting pathways.Proton conductivity is traditionally affected by proton concentration,mobility,hopping sites,etc.in metal-organic frameworks(MOFs).The influence of proton conducting pathways' profile has not been demonstrated owing to lacking suitable model.Thus,building up different proton-conducting pathways within one MOF would be a promising solution.MIL-101 contains two types of tunnels with zigzag and linear profiles constructed by the cages with different sizes.And its cavities have large accessible windows which make artificially constructing hydrogen bond networks by introducing suitable guests possible.Keggin-type polyoxometalate H3PW12O40(HPW)is a promising choice in virtue of its unique nano size,strong Br?nsted acidity,good stability and abundant proton-hopping sites.Two hydrogen bond networks with different profiles of zigzag and linear are successfully constructed by situating HPWs in targeting pores of MIL-101.The results of proton conduction measurements demonstrate that linear pathway provide over twice as fast proton diffusion rate comparing with its zigzag counterpart,and further verified that linear pathways promoted proton diffusion as compared to zigzag pathways.These results provide a new viewpoint for the design of MOF-based proton-conducting materials besides optimizing proton concentration,mobility,and hopping sites.Further,we improve HPW-impregnated MIL-101 with flexible polyamine results a conductivity of 1.52×10-2 S cm-1 at 80? 100% RH.