Ion‐Pairing Assemblies of Deprotonated <i>Meso</i> ‐Hydroxyporphyrins as π‐Electronic Anions

Charged π-electronic systems provide ion-pairing assemblies, which would exhibit fascinating properties by appropriate modifications. Deprotonation of acid-unit-appended π-electronic systems, such as meso-hydroxyporphyrins (MHPs), enables the formation of π-electronic anions, for which the substituents modulate the electronic states and assembly modes. In this study, MHP Pt^II complex anions, bearing electron-donating phenyl groups and electron-withdrawing C₆F₅ groups, formed various ion pairs in combination with cations, including triazatriangulenium and porphyrin Au^III complex cations. Single-crystal X-ray analysis revealed solid-state ion-pairing assemblies of the MHP Pt^II complex anions with charge-by-charge packing modes, where the arrangements of the components were dependent on the peripheral substituents and coexisting countercations. Hirshfeld surface analysis and energy decomposition analysis (EDA) calculations revealed that ion-pairing assembly modes were mainly governed by ⁱπ-ⁱπ interactions between the MHP Pt^II complex anions and countercations.