Lewis Acid Guests in a {P8W48} Archetypal Polyoxotungstate Host: Enhanced Proton Conductivity via Metal‐Oxo Cluster within Cluster Assemblies

Complexes made by hosts that completely surround their guests provide a means to stabilize reactive chemical intermediates, transfer biologically active cargo to a diseased cell, and construct molecular-scale devices. By the virtue of inorganic host-guest self-assembly, nucleation processes in the cavity of a {P₈ W₄₈ }-archetype phosphotungstate has afforded a nanoscale 16-Al^III -32-oxo cluster and its Ga^III analogue that contain the largest number of Al^III /Ga^III ions yet found in polyoxometalate (POM) chemistry. Interestingly, the rich Lewis acid Al^III centers within the Lewis base POM support shows an exceptional proton conductivity of 4.5×10^-2 S cm^-1 (85 °C, 70 % RH; RH: relative humidity), which is by far the highest conductivity reported among POM-based single-crystal proton conductors.