Controlled super-structures of hydrogen bonding Ni(II) complexes organizing one-dimensional double cationic arrays

Anionic tris-biimidazolato Ni(II) complexes ([Ni(Hbim)3]-), which represent a hydrogen-bonding molecular building blocks, are self-organized to form honeycomb-sheet super-structures connected with complementary intermolecular hydrogen bonds by cations in the crystal. The crystal formed by the stacking of the sheets has nano-channel structures having width of ca. 2 nm-scale width, which confines one-dimensional double columnar arrays of cationic molecules. Thus, relative large cations such as potassium crown-ether complexes and PPh4+ can generally cause [Ni(Hbim)3]- to assemble to a honeycomb-sheet formation forming these channel structures. However, smaller cations such as 4-phenylethyl pyridinuim and trimethyl ethynyl ammonium also lead to the same honeycomb-sheet network by forming the cationic ion-pairs containing an anion in the channels; this is a new finding that we present in this paper.