Synthesis, crystal structures, and properties of two novel compounds containing triphosphonate groups

<p>Two novel phosphonate compounds (H₂L)·Hphen (<b>1</b>) and [Ca(HL)(H₂O)]_n·3.5nH₂O (<b>2</b>) (L = N(CH₂PO₃H)₃³⁻) were synthesized under hydrothermal conditions. Compound <b>1</b> features a chain structure in the ac plane, where HL²⁻ anions are interconnected through sharing hydrogen ions to form a 1D zigzag type. Compound <b>2</b> features a layered structure in the ab plane, which has inorganic calcium cores with the organic part of the phosphonate anions being encircling the cores through coordination actions. The free water molecules can form hydrogen bonds with the coordinated water molecules and phosphonate oxygen atoms, which are able to link the adjacent layers to generate a 3D network structure. In addition, the thermal stability and photoluminescence properties were also studied.