Chiral Self-Assembly of Zinc and Magnesium Porphyrins with Enantiopure Cyclohexanohemicucurbiturils in Solution and in Solid State

Chiral self-assembled supramolecular networks offer great potential for new chiral materials. We report the predictable self-assembly of metalloporphyrins with chiral cyclohexanohemicucurbit[n]urils (cycHC[6] and cycHC[8]), where cycHC[n] chirality is transferred to achiral porphyrins in solution and the solid state. Solvent and porphyrin substituents directed the formation of 31 novel complexes characterized by single-crystal X-ray diffraction. All complexes feature metal-urea coordination centers, with architectures ranging from discrete complexes to 1D, helical 1D, and 2D square-grid coordination polymers, governed by the shape and binding strength of cycHC[n]s. Noncovalent interaction analysis highlighted van der Waals interactions alongside metal-oxygen coordination. In solution, binding strengths ranged from 690 to 1,840,000 M⁻¹, while electronic circular dichroism (ECD) g-factors remained consistent. Solid-state measurements revealed a 10-fold increase in induced ECD intensity in the Soret region, attributed to chiral aggregation and interporphyrin exciton coupling. Vibrational circular dichroism showed chirality induction in the infrared range, with the g-factor of cycHC[6] carbonyl signals increasing 10-fold upon complexation. These results demonstrate the robustness of hemicucurbituril-metalloporphyrin supramolecular systems for developing advanced chiral sensing materials.