Mixed-solvothermal syntheses, structures and luminescence properties of two new Zn(II) phosphonates with layered and 3D framework structures

Two new zinc phosphonates with 2-hydroxyphosphonoacetic acid (HPAA) and 1-hydroxyethylidenediphosphonic acid (hedpH4), [Zn2{HO3PCH(OH)CO2}3]·2NH2(CH3)2·3H2O (1) and [Zn3{CH3C(OH)(PO3)2}2]·2NH2(CH3)2·H2O (2) have been synthesized under mixed-solvothermal conditions at 160 °C and structurally characterized by X-ray single-crystal diffraction, X-ray powder diffraction, infrared spectroscopy and elemental analysis. The structure of compound 1 comprises Zn1O6 and Zn2O6 octahedra connected by [HO3PCH(OH)CO2]2− to form a 2D layered structure with one-dimensional channel system along c-axis direction, and the protonated dimethylamine cations are being located between two adjacent layers. Interestingly the layers of 1 arranged in an alternative sequence (ABAB). Compound 2 features a 3D framework structure with channels along the b- and c-axis, respectively. The charge-compensating protonated Hdma+ cations and solvate water molecules are located inside the channels along the c-axis. A notable feature for compound 2 is the presence of the alternate left- and right-handed helical chains in the structure. The luminescence properties of compounds 1 and 2 have also been studied.