Effects of Anionic Geometries on Hydrogen-Bonding Networks of 1-(4-pyridyl) Piperazine

Abstract

A series of new salts have been obtained by the self-assembly of 1-(4-pyridyl) piperazine and inorganic ions or metal chloride in the hydrochloric acid medium, i.e. (C₉H₁₅N₃ ²⁺)·(Cl⁻)₂ (1) (C₉H₁₅N₃ ²⁺)·(NO₃ ⁻)₂ (2), (C₉H₁₅N₃ ²⁺)·(CuCl₄ ²⁻) (3), (C₉H₁₅N₃ ²⁺)·(CoCl₄ ²⁻) (4), (C₉H₁₅N₃ ²⁺)·(ZnCl₄ ²⁻) (5), {(C₉H₁₅N₃ ²⁺)·[Mn(H₂O)₂Cl₄ ²⁻]}·H₂O (6), (C₉H₁₄N₃ ⁺)·(Sb₂Cl₇ ⁻) (7) and (C₉H₁₅N₃ ²⁺)·(PbCl₄ ²⁻) (8). Structural analyses indicate that different anionic structure (e.g. spherical, trigonal planar, tetrahedral, octahedral, polyhedral and chain) can induce the formation of diverse architectures, influencing the crystallization ratio, the protonated number and the final structures. Extensive intermolecular interactions have been utilized for the self-assembly of diverse frameworks, ranging from strong X–H···Y (X=O, N; Y=Cl, O) hydrogen bonds to weak C–H···M (M=O, Cl) interactions. Among them, 3D hydrogen-bonding architectures are observed in 1–7 but only a 2D hydrogen-bonding architecture is observed in 8. Salt 6 crystallizes with water molecules but the others do not. Interestingly, the anions of salts 7 and 8 are dinuclear and 1D complex ions, respectively.

Graphical Abstract

A series of supramolecular salts have been obtained by the self-assembly of 1-(4-pyridyl) piperazine and inorganic acids or metal chloride in the hydrochloric acid medium. Structural analyses indicate that different anionic structure (e.g. spherical, trigonal planar, tetrahedral, octahedral, polyhedral and chain) can induce the formation of diverse supramolecular architectures, influencing the crystallization ratio, the protonated number and the final structures.