μ-4,4′-Bipyridine-κ2N:N′-bis[tetraaqua(4,4′-bipyridine-κN)dimanganese(II)] bis(4-aminobenzoate) bis(perchlorate)–4,4′-bipyridine–water (1/2/4): a supramolecular system constructed by π–π and hydrogen-bond interactions

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The title dinuclear manganese compound, [Mn(2)(C(10)H(8)N(2))(3)(H(2)O)(8)](C(7)H(6)NO(2))(2)(ClO(4))(2)·2C(10)H(8)N(2)·4H(2)O, (I), has an inversion center located midway between the Mn(II) ions. Each Mn(II) ion has a distorted octahedral coordination environment, defined by two mutually cis N atoms from two different 4,4'-bipyridine (4,4'-bipy) ligands and four O atoms from four water molecules. The asymmetric unit contains cationic [Mn(4,4'-bipy)(1.5)(H(2)O)(4)](2+), one isolated 4,4'-bipy molecule, one 4-aminobenzoate ion, one disordered perchlorate ion and two uncoordinated water molecules. In the dinuclear manganese cationic unit, one 4,4'-bipy acts as a bidentate bridging ligand between two Mn(II) ions, while the other two act only as monodentate terminal ligands, giving rise to a 'Z-type' [Mn(2)(4,4'-bipy)(3)(H(2)O)(8)] host unit. These host units are linked to each other via face-to-face π-π stacking interactions between monodentate terminal 4,4'-bipy ligands, generating a zigzag chain. The corners of these chains, defined by Mn(OH)(4) units, are surrounded by the solvent water molecules and the carboxylate O atoms of the 4-aminobenzoate ions, and all of these are connected to each other via strong O-H···O hydrogen-bond interactions, leading to a three-dimensional grid network with a large cavity running along the b axis of the unit cell. The isolated 4,4'-bipy molecules, the 4-aminobenzoate and perchlorate anions and the water molecules are encapsulated in the cavities by numerous hydrogen-bond interactions.