Self-assembly of organic acid–base compounds from 2-D layered network to 3-D supramolecular framework: synthesis, structure and photoluminescence

Abstract

The reactions of organophosphonic acids [1-aminoethylidenediphosphonic acid (AEDPH4), 1-aminopropane-1,1,3-triphosphonic acid (APTPH6)] and 2,2′-bipyridyl-like ligands [2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen)] under low temperature hydrothermal conditions yielded four acid–base compounds, namely, (AEDPH3)·(H2bipy)1/2·2H2O (1), (AEDPH3)·(Hphen)·2H2O (2), (APTPH5)·(Hbipy)·2H2O (3) and (APTPH4)·(Hphen)·(H3O)·3H2O (4). These four compounds were characterized by a single crystal X-ray diffraction method, elemental analysis (EA), infrared spectrometry (IR) and thermogravimetric analysis (TGA). They all crystallize in a triclinic system, with a P space group. In particular, the supramolecular structures of organophosphonic acids in these four compounds are different. In compounds 1 and 2, the dimer or dimer chains are formed by hydrogen bonds between adjacent phosphonate groups, while in compounds 3 and 4 two-dimensional (2-D) layered networks are constructed by the hydrogen bonds between the phosphonate groups. The diversity of supramolecular structures is due to the difference of AEDPH4 and APTPH6 ligands. Additionally, their luminescence in the solid state has also been studied at room temperature.