Polyoxometalates (POMs) have been a popular motif in crystal engineering. In this work, seven ionic crystals based on Keggin- or Dawson-type POMs and mononuclear Bi(III) complexes were synthesized. The center exhibited triangular dodecahedron, square antiprism, pseudo-cubic eight-coordination geometries, with DMSO DMF as ligands. showed polymorphic transformations, high proton conductivities de...