Anion-π stacks of Lindqvist superoctahedra [Mo6O19]2− supported by caffeinium and theophyllinium cations

•Two new caffeinium and theophyllinium Lindqvist hexamolybdates reveal significance of anion⋅⋅⋅π interactions.•Electron deficient aromatic cations generate anion⋅⋅⋅π⋅⋅⋅anion links when stacked to the oxide surfaces of POM anions.•Additional CH3 group at the cation frame productively contributes to the total interaction energies.•Hirshfeld surface analysis detects enhancement of anion⋅⋅⋅π bonding in the case of caffeinium vs. theophyllinium.