Construction of 3D layer-pillared homoligand coordination polymers from a 2D layered precursor

Herein, we present a new method for preparing homoligand 3D coordination polymers. First, a layered metal organic framework Zn-3(BDC)(3)(H2O)(2)(.)4DMF 1 (BDC is terephthalate, DMF is N,N-dimethylformamide) was fabricated from a H2BDC by liquid-liquid diffusion. Second, the layered product, 1, was used as a precursor to solvothermally react with further H2BDC at 140-180 degrees C, resulting in two products of BDC insertion into the layered structure. These are [Zn-3(p-BDC)(4)](.)2HPIP, 2 (HPIP is partly protonated piperazine), and [Zn-3(p-BDC)(3)(H2BDC)](.)(C6H15NO)(.) H(2)O(.)3DMF, 3 (C6H15NO is triethylamine N-oxide). Single-crystal X-ray diffraction shows that 2 possesses a layer-pillared structure of mu(4)-BDC, with 1D channels, while 3 has a layer-pillared structure of mu(2)-BDC, with 2D channels. N-2-sorption experiments show 3 has a relatively high BET surface area of 750 m(2)/g. It is proposed that 2 follows the crystal growth mechanism of Ostwald ripening, whereas the crystal structure of 3 might be formed by an insertion mechanism.