Pore "Softening" and Emergence of Breathability Effects of New Keplerate Nano-Containers

The self-assembly of porous molecular nanocapsules offer unique opportunities to investigate a range of interesting phenomena and applications. However, to design nanocapsules with pre-defined properties, thorough understanding of their structure-property relation is required. Here, we report the self-assembly of two elusive members of the Keplerate family, [Mo₁₃₂ Se₆₀ O₃₁₂ (H₂ O)₇₂ (AcO)₃₀ ]^42- {Mo₁₃₂ Se₆₀ } 1 and [W₇₂ Mo₆₀ Se₆₀ O₃₁₂ (H₂ O)₇₂ (AcO)₃₀ ]^42- {W₇₂ Mo₆₀ Se₆₀ } 2, that have been synthesised using pentagonal and dimeric ([Mo₂ O₂ Se₂ ]²⁺ ) building blocks and their structures have been confirmed via single crystal X-ray diffractions. Our comparative study involving the uptake of organic ions and the related ligand exchange of various ligand sizes by the {Mo₁₃₂ Se₆₀ } and previously reported Keplerates {Mo₁₃₂ O₆₀ }, {Mo₁₃₂ S₆₀ } based on the ligand exchange rates, revealed the emergence of increased "breathability" that dominates over the pore size as we transition from the {Mo₁₃₂ S₆₀ } to the "softer" {Mo₁₃₂ Se₆₀ } molecular nano-container.