Zeolite Ionic Crystals Assembled through Direct Incorporation of Polyoxometalate Clusters within 3D Metal−Organic Frameworks

Polyoxometalate-based metal−organic frameworks {[Gd(dpdo)4(H2O)3](PMo12O40)(H2O)2CH3CN}n (2), {[Dy(dpdo)4(H2O)3](PMo12O40)(H2O)2CH3CN}n (3), {[Gd(dpdo)4(H2O)3](H3O)(SiMo12O40)(dpdo)0.5(CH3CN)0.5 (H2O)3}n (4), {[Ho(dpdo)4(H2O)3](H3O)(SiMo12O40)(dpdo)0.5(CH3CN)0.5(H2O)3}n (5), {[Ni(dpdo)2(CH3CN) (H2O)2]2(SiMo12O40)(H2O)2}n (6),
and {[Ni(dpdo)3]4(PW12O40)3[H(H2O)27(CH3CN)12]}n (7) (where dpdo is 4,4‘-bipyridine-N,N‘-dioxide) were constructed
via self-assembly by embedding Keggin-type polyanions within the intercrystalline voids as guests or pillars.
Compounds 2 and 3 are isomorphic and exhibit three-dimensional (3D) noninterwoven 64 frameworks with distorted-honeycomb cavities occupied by the polyanions. Compounds 4 and 5 are comprised of 3D noninterwoven frameworks
formed by linking the adjacent folded sheets through hydrogen bonds and π−π stacking interactions relative to the
free isolated dpdo ligand. Compound 6 is a pillar-layered framework with the [SiMo12O40]4- anions located on the
square voids of the two-dimensional bilayer sheets formed by the dpdo ligands and nickel(II) ions. Compound 7 is
a 3D metal−organic framework formed by nickel(II) and 4,4‘-bipyridine-N,N‘-dioxide with the globular Keggin-structure [PW12O4]3-anion as the template. A large protonated water cluster H+(H2O)27 is trapped and stabilized
within the well-modulated cavity.