Synthesis, structure, and surface photovoltage property of two new cobalt (II) phosphonates with 2D layered structure

Two new cobalt phosphonates, [enH2]0.5[Co(HL)(H2O)] · H2O (1) and [Co2(HL)(H2L)2] · 2NH(CH3)2 · 3H2O (2) (H3L = 2-hydroxyphosphonoacetic acid; en = ethylenediamine), have been synthesized under hydrothermal conditions and structurally characterized by X-ray single-crystal diffraction, X-ray powder diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. For compound 1, Co(II) atoms are octahedrally coordinated. The CoO6 octahedra and CPO3 tetrahedra are linked by HL2 − into a 2D layered structure in the bc-plane. The ethylenediamine molecules and solvate water molecules are located between two adjacent layers. The structure of compound 2 composed of Co1O6 and Co2O6 octahedra via bridging phosphonate ligands leads to a 2D layered structure with one-dimensional channel system along c-axis direction. The dimethylamine molecules and solvate water molecules are located between two adjacent layers. The surface photovoltage properties of compounds 1 and 2 have also been studied.