Dynamic behaviour of a soft porous crystal based on a tetra-4-(4-methyl-pyridinium) phenylmethane salt

A new, soft porous crystal of general formula TMPPM(PF(6))(4) has been assembled by combining the rigid tetrahedral tecton tetra-4-(4-methyl-pyridinium)phenylmethane (TMPPM(4+)) as cationic organic linker and hexafluorophosphate PF6- as anionic node. By dissolving the solid compound in acetone, the solvated form TMPPM(PF(6))(4)& sdot;0.67(Acetone) is obtained, whose open-pore structure (op-TMPPM(PF(6))(4)) contains one-dimensional channels of octagonal cross-section where the disorder solvent is accommodated. By heating the crystals, the solvent is released in a single-crystal-to-single-crystal transformation that leads to a closed-pore phase (cp-TMPPM(PF(6))(4)) comprising unconnected voids. The reversible, dynamic adsorption-desorption process was followed by ex situ and in situ PXRD analyses, respectively. Moreover, the release of acetone over time was shown to be in good agreement with the guest-packing efficiency rule.