From 1D to 3D Single-Crystal-to-Single-Crystal Structural Transformations Based on Linear Polyanion [Mn<sub>4</sub>(H<sub>2</sub>O)<sub>18</sub>WZnMn<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>(ZnW<sub>9</sub>O<sub>34</sub>)<sub>2</sub>]<sup>4–</sup>
induced by transition-metal cations (Co2+ and Cu2+) and solvent molecules. These solid materials present interesting catalytic activity for the oxidative aromatization of Hantzsch 1,4-dihydropyridines that is dependent on the inserted heterogeneous metal cations.