Construction of Three-Dimensional Honeycomb-like Supramolecular Host Network with Dicationic Metallotecton Cu[(2-C4H3N2)2C(OH)2]22+ through Cooperative Hydrogen-Bonding and Anion-π Interactions

In situ carbonyl hydration of di-2-pyrazinylmethanone (2-C4H3N2)(2)CO upon metal coordination leads to three isostructural mononuclear copper(II) complexes Cu(L-1')(2)X-2 center dot nH(2)O (L-1' = (2-C4H3N2)(2)C(OH)(2), n = 4.5; X = ClO4-, BF4-, PF6-) whose three-dimensional supramolecular host network, which contains honeycomb-like channels that accommodate water guests, is constructed from the consolidation of mononuclear Cu(L-1')(2)(2+) metallotectons via cooperative hydrogen-bonding and anion-pi interactions. Replacing one pyrazinyl ring of L-1' by a less pi-acidic pyridyl ring to yield a related ligand leads to the formation of Cu(L-2')(2)(ClO4)2 center dot 4H(2)O 4 (L-2' = (2-C4H3N2)(2-C5H4N)C(OH)(2)), which exhibits a different supramolecular framework of lesser stability on account of reduced anion-pi bonding interaction.