Exploration of structural motifs influencing solid-state conformation and packing of unclosed cryptands sharing the same 19-membered macrocyclic core

Abstract

The crystal structures of a series of readily available, highly crystalline bisamide unclosed cryptands (UCs), sharing the same 19-membered macrocyclic core were thoroughly studied in order to rationalize their organization in the solid state. Despite structural variations introduced into intraannular substituents, mode of their attachment to the macrocyclic core, and relative acidity of exterior amide protons, UCs adopted only three well-defined geometries in all 10 analyzed crystals. This structural resemblance between conformations of UCs, however, is not translated into similarities in terms of intermolecular interactions and crystal packing. This contradicting intra- and intermolecular solid-state behavior is likely connected with an ability of these macrocyclic compounds to engage in numerous interactions of comparable energy within the crystal lattice.