Hydrothermal synthesis and characterization of two new three-dimensional titanium phosphates

Two new three-dimensional titanium phosphates with the formulas Ti-2(HPO4)(3)(PO4).0.5C(4)N(2)H(12) (1) and Ti-7(HPO4)(6)(PO4)(6).C6N2H14 (2) have been prepared hydrothermally from titanium powder, phosphoric acid, and structure-directing organic amines. The as-synthesized products were characterized by powder X-ray diffraction, IR spectroscopy, thermogravimetric, and differential thermal analyses (TG-DTA). The structures were solved by single-crystal X-ray diffraction analysis. Crystal data are as follows: Ti-2(HPO4)(3)(POA).0.5C(4)N(2)H(12) (1), monoclinic, space group P2(1)/n (no. 14), a = 10.7455(11) Angstrom, b = 6.3469(6) Angstrom, c 20.4800(19) Angstrom, beta = 104.286(3)degrees, V= 1353.6(2) Angstrom (3), Z = 4; Ti-7(HPO4)(6)(PO4)(6).C6N2H14 (2) trigonal, space group R-3 (no. 148), a = 16.8640(14) Angstrom, b 16.8640(14) Angstrom, c 12.334(2) Angstrom, V = 3037.7(6) Angstrom (3), Z = 3. Both structures are of the open-framework type, and the frameworks are built from TiOs octahedra and PO4, PO3(OH), and/or PO2(=O)(OH) tetrahedral units. There exist eight-membered ring channels, in which the diprotonated organic amine molecules are entrapped along the [010] direction for 1 and along the [001] direction for 2.