Macrocyclic Polyoxometalates: Selective Polyanion Binding and Ultrahigh Proton Conduction

Abstract

The rational development of an anion templation strategy for the construction of macrocycles has been historically limited to small anions, but large polyoxoanions can offer unmatched structural diversity and ample binding sites. Here we report the formation of a {Mo22Fe8} macrocycle by using the Preyssler anion, [NaP5W30O110]14− ({P5W30}), as a supramolecular template. The {Mo22Fe8} macrocycle displays selective anion binding behavior in solution. In the solid state, the 1 : 2 host–guest complex, {P5W30}2⊂{Mo22Fe8}, transports protons more effectively, through an extended hydrogen‐bonding network, than a related 1 : 1 complex where the guest is completely encapsulated. The results highlight the great potential this anion templation approach has in producing macrocyclic systems for selective anion recognition and proton conduction purposes.

Highly Effective Proton-Conduction Matrix-Mixed Membrane Derived from an -SO3H Functionalized Polyamide

“…Great efforts have been dedicated to this mission, and numerous materials such as polyoxometalates [10,11], graphynes [12,13], recently developed porous materials [14][15][16][17], and so on have been constructed and studied thus far as proton-conductive electrolytes for application in PEM fuel cells. Among these functional materials, Nafion, a perfluorinated sulfonated polymer that shows an excellent proton conductivity and durability has gradually become a commercially accessible PEM electrolyte, although many issues in its fabrication and application still need to be overcome [18][19][20].…”

Facile construction of a highly proton-conductive matrix-mixed membrane based on a –SO3H functionalized polyamide

“…Diverse materials, which include polyoxometalates, 10,11 graphynes, 12,13 and even recently developed porous materials, 14–17 have been synthesized and investigated as proton-conductive electrolytes so far. Among these functional materials, a perfluorinated sulfonated polymeric electrolyte, i.e.…”

Highly Effective Proton-Conductive Matrix-Mixed Membrane Based on a −SO3H-Functionalized Polyphosphazene

“…Therefore, the development of novel proton-conductive electrolytes is a fundamental important step in the process of commercializing PEM fuel cells. 7−9 Among the studied proton-conductive electrolytes such as graphynes, 10,11 polyoxometalates, 12,13 and some porous materials, 14−17 a perfluorinated sulfonated polymeric electrolyte, Nafion, has been employed as a PEM electrolyte because of its high proton conductivity and stability, although future large-scale practical utilization is still inhibited by its high cost, synthetic difficulties, and restricted working conditions. 18−20 Inspired by the success of Nafion, −SO 3 H functionalities have also been introduced into diverse materials and evaluated as Nafion alternatives to resolve the issues on the road to its largescale practical application.…”

“…Among the studied proton-conductive electrolytes such as graphynes, , polyoxometalates, , and some porous materials, − a perfluorinated sulfonated polymeric electrolyte, Nafion, has been employed as a PEM electrolyte because of its high proton conductivity and stability, although future large-scale practical utilization is still inhibited by its high cost, synthetic difficulties, and restricted working conditions. − Inspired by the success of Nafion, −SO 3 H functionalities have also been introduced into diverse materials and evaluated as Nafion alternatives to resolve the issues on the road to its large-scale practical application. − Using the Cu­(I)-CAAC click reaction, − we also grafted the −SO 3 H groups into a triazole-based porous organic polymer (TaPOP-1) during the in situ preparation process and a metal–organic framework entitled UiO-66 by the post-modification treatment, and investigations revealed that their proton conductivities were significantly increased in both the sulfonated TaPOP-1-SO 3 H and UiO-66-SO 3 H. , Despite the fact that numerous materials have been synthesized and studied for proton conduction, effective and economically affordable proton-conductive electrolytes are still urgently required for the large-scale application of PEM fuel cells in the upcoming “hydrogen economy” society.…”