Hierarchy and Synergy of Anion-π, Hydrogen Bonding and π-π Interactions in Multicomponent Ionic Hybrid Architectures

The knowledge of different types of anion-binding modes offered by π-acidic HAT(CN)₆ and resorcinol-like double proton donors was successfully applied to construct unprecedented ternary {[HAT(CN)₆];[PG];[X^-]₂} (HAT(CN)₆ = 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile, PG = phloroglucinol; X = Cl, Br) synthons both in the solid state and in solution. These systems feature an adaptative coexistence of anion-π, hydrogen bonding, and π-π interactions, all supported by multiple phenyl embraces of PPh₄ ⁺ cations. The key contributing motifs - {[HAT(CN)₆];[X^-]₂}, {[PG];[X^-]₂}, and {[HAT(CN)₆];[PG]} - successfully followed the patterns observed in related binary systems. Combined experimental-computational SC XRD, UV-Vis, NMR (¹H, ¹³C, and ⁸¹Br), and quantum-chemical approaches disclosed a progressive and hierarchical structural build-up with clear signatures of synergistic effects involving all three interactions and a well-defined role of each interaction type in synthons stabilization and shaping intermolecular charge-transfer properties within the studied adducts. This work introduces a new library of multicomponent ionic systems, paving the way for the future development of extended topological molecular organic-inorganic architectures and properties that may be governed by the hierarchy and/or synergy of noncovalent interactions.