Hydrothermal synthesis and characterization of the first 1-D indiumphosphate chain In 2(HPO 4) 2(H 2PO 4) 2F 2·C 4N 2H 12, a precursor for high dimensional structures

Abstract

The first one-dimensional (1-D) indiumphosphate chain, In 2(HPO 4) 2(H 2PO 4) 2F 2·C 4N 2H 12 ( 1), has been hydrothermally prepared using piperazine (PIP) as a template. The structure consists of infinite chains of trans, trans-corners-sharing InO 4F 2 octahedra with the adjacent octahedra being bridged by tetrahedral PO 3(OH) and PO 2(OH) 2 units, which are H-bonded with amine groups of the organic cations. Interestingly, this macroanionic chain InP 2O 8H 3F − is similar to that found in the mineral tancoite-like chains and has potential to further set up higher-dimensional networks. On heating 1 in the presence of additional phosphoric acid at 180 °C under hydrothermal condition, compound 2, In 2(OH)(H 2O)(PO 4) 2·H 3O·H 2O, possessed a 3-D structure building from the repetition of a secondary building unit is obtained. When 1 is heated with additional PIP, an unknown phase, compound 3 is formed. Finally, on treatment with another amine, such as diethylenetriamine or 1,4-diaminobutane, at 180 °C, 1, as a precursor, can convert into a previously known 3-D framework structure with 16-membered ring compound 4. Compounds 1 and 2 are determined by single-crystal X-ray diffraction. Furthermore, 1 is characterized by X-ray powder diffraction, IR spectroscopy, inductively coupled plasma analysis, thermogravimetric analysis and differential thermal analysis.