Isostructurality or Not: A Deep Insight into the Selective Formation of Spironolactone Solvates

The selective formation of isostructuralcrystals was investigatedwith a family of spironolactone isostructural and non-isostructuralsolvates. The formation of isostructural solvate is a delicate energybalance between the energy loss caused by the expansion of the frameworkand the addition of host center dot center dot center dot guest interactions. Thedirectionality of the host center dot center dot center dot guest interactions shouldbe carefully considered in the isostructurality-based crystal design. Isostructurality is a potential toolto design crystalswith tailoredarrangements, especially for multicomponent systems, but researchinto its formation mechanism is still limited to date. Herein, a familyof spironolactone (SPI) isostructural and non-isostructural solvateswas investigated to explore the selective formation of isostructuralcrystals. The SPI framework, dominated by van der Waals forces, isrobust and flexible, with different solvent molecules in its channelsplaying the same structural role. The formation of the SPI isostructuralsolvate is a delicate energy balance between the energy loss causedby the expansion of the SPI framework and the addition of SPI center dot center dot center dot solventinteractions. Besides the size and functional groups of solvent molecules,the directionality of the SPI center dot center dot center dot solvent interactionsshould also be carefully considered in the isostructurality-basedcrystal design. In addition, weak interactions seem to be regardedas potential design elements for organic host architectures.