题 目: Hydrophilic vs Hydrophobic: Exploring Facet-Dependent Proton Transport Channels in Single Crystal of Ring-Shaped Trimeric Isopolytungstate
作 者: Mengnan Yang, Lijuan Xiong, Shiyan Ji, Yao Zhang, Weixia Shi, Huafeng Li, Pengtao Ma, Jingping Wang,* and Jingyang Niu*
刊 名: Chem. Mater.
年卷页: 2024, 36, 8929-8935.
摘 要：Research on the facet-dependent anisotropic proton conduction of single crystals is advantageous to visualize the molecular level mechanism of polyoxometalate (POM)-based crystalline proton conducting materials. Herein, we constructed a novel ring-shaped trimeric isopolytungstate {(RuW11O37)O}318- (1a) with an inner hydrophobic space and an outer hydrophilic surface. After assembly through the hydrated cation linkers, polyanion 1a rings formed the single-crystal Rb11Na6H·1a·36H2O(1) with (0 
0), (101), and (11) faces, which have different sizes and types (hydrophilic-Grotthuss-type and/or hydrophobic-Vehicle-type) of proton transport channels. Accordingly, proton conductivity (σ) of single-crystal 1 can reach 3.84×10-2Scm-1along the direction perpendicular to the (00) face at 358K under 85% relative humidity (RH), which is equivalent to that of crystal pellet (2.09×10-2Scm-1) and accompanied by the ratio of σ(010):σ(101):σ(111)=121:5:1. It reveals a visible (00) facet-dependent proton-conducting pathway in the large-sized hydrophilic pore channels through a water-induced hydrogen bond network under the Grotthuss hopping mechanism.
