Hydrothermal Synthesis and Structural Characterization of Three Organically Templated Titanium Phosphates: Ti2(HPO4)2(PO4)2·C2N2H10, Ti3(H2PO4)(HPO4)3.5(PO4)2·C2N2H10, and Ti7(HPO4)6(PO4)6·C3N2H12

Abstract

Three organically templated titanium phosphates with the formulas Ti-2(HPO4)(2)(PO4)(2). C2N2H10 (1), Ti-3(H2PO4)(HPO4)(3.5)(PO4)(2).C2N2H10 (2), and Ti-7(HPO4)(6)(PO4)(6).C3N2H12 (3) have been prepared hydrothermally from titanium powder, phosphoric acid, and structure-directing organic amines. The as-synthesized products are characterized by powder X-ray diffraction, P-31 MAS NMR spectroscopy, IR spectroscopy, and thermogravimetric and differential thermal analyses (TG-DTA). The structures have been solved by single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, P (1) over bar, a = 6.3066(17) Angstrom, b = 10.181(4) Angstrom, c = 12.644(3) Angstrom, alpha = 102.14(2)degrees, beta = 102.49(3)degrees, gamma = 90.00(2)degrees, Z = 2. Crystal data for 2: triclinic, P (1) over bar, a = 10,3183(9) Angstrom, b = 10.7501(10) Angstrom, c = 10.8315(10) Angstrom, alpha = 73.436(2)degrees, beta = 79.648(2)degrees, gamma = 83.260(2)degrees, Z = 2. Crystal data for 3: trigonal, R (3) over bar, a = 16.4993(15) Angstrom, b = 16.4993(15) Angstrom, c = 12.704(3) Angstrom, Z = 3. Their frameworks are all built up with TiO6 octahedra and PO4, PO2(OH)(2), PO3(OH) and/or PO2(=O)(OH) tetrahedral units. Compound 1 is an ethylenediamine intercalated layered titanium phosphate in which the layers are similar to that of gamma-type titanium phosphate. Both 2 and 3 are of open-framework type, and the diprontonated organic amine molecules are entrapped in 12-membered-ring channels for 2 and 8-membered-ring channels for 3.