Hydrothermal Synthesis And Research Of Microporous Indium Phosphites And Posphates

Inorganic microporous materials have attracted considerable attention due to not only their unique pore architectures, but also potential applications in catalysis, adsorption, ion-exchange, separation and host-guest assemblies. And the rational design and synthesis of new microporous compounds, as well as the development of new synthetic ways are becoming the topics of microporous chemistry. Since the synthesis of the first aluminophosphate by E. M. Flanigen in 1982, metal phosphates have been studied widely over the past two decades. A large number of these compounds, including aluminophosphates, gallium phosphates, indium phosphates, and zinc phosphates, etc, have been prepared under hydrothermal or solvothermal conditions in use of different metal cations, with diverse organic amines as templates or structure-directing agents. In the synthesis of this kind of materials, organic component can influence the nucleation and growth of the inorganic compounds, and control the microstructure of the inorganic framework. The synthesis of these compounds can have great significance in crystallography and the study of biomineralization. Since the syntheses of vanadium phophites in the presence of piperazinium cation as structure-directing agent by Zubieta et al. in 1995, the interest in the synthesis of new metal phosphites has been aroused. The open framework metal phosphates were studied with focus on the change of the metal cations, and little attention to anions. Recently, it is already found that the new inorganic microporous materials, with novel structure and diverse components, may consist of the pseudo pyramidal geometry phosphite [HPO32-] units other than the tetrahedral phosphate [PO43-] groups. Up to date, transition metal phosphites containing V(III), Fe(III), Co(II), Mn(II), Zn(II) and Cr(III) have been extensively studied, and the compounds with their various properties have been reported. Little organically-templated main block metal Be(II), Ga(III), In(III) phophites were also prepared. The successful syntheses of these new compounds with open-framework open a new field for the microporous compounds.Compared with many reported microporous compounds of zinc phosphites, etc, indium phosphites have little been reported; and similarly, the number of the indium phosphates is also small by contrast with large numbers of metal phosphates. In order to be affluent in structure and compositions, and offer the basic data for the law research of the inorganic microporous compounds, the goal of this work is to synthesis and preparation of indium phosphites and phosphates under hydrothermal conditions. The study results obtained in the experiments as follows:1. The first two dimensional (2-D) layers indium phosphite, In2(HPO3)4·NH3(CH2)6NH3·H2O (1), has been hydrothermally prepared using 1,6-Hexanediamine as the template. The compound 1 crystallizes in the orthorhombic system and space group Ibca, its framework may be seen to consist of octahedral InO6 and pseudo pyramidal HPO3, which form the layers containing 4-, 6-member rings along c axis direction, and the layers are pillared through 1,6-Hexanediamine. And the diprotonal 1,6-Hexanediamine exists between the layers and balances the negative charges.2. A new 3-D indium phosphite with eight-menber ring, [In2(HPO3)4]·(NH3CH2CH2NH3) (2), has been prepared hydrothermally using ethylenediamine as the template. The compound 2 crystallizes in the monoclinic system and space group P2/n, its framework may be seen to consist of octahedral InO6 and pseudo pyramidal HPO3, which form the layers containing 8-member ring along a axis direction, and the layers are connected to produce a three-dimensional framework, and the 1-D straight 8-menber rings channels exit along [506] direction. The diprotonal ethylenediamine exists between the channels and balances the negative charges.3. Three new 3-D indium phosphites, [In4(HPO3)7]·(H2O)3·(NH3CH2CH2NH3)·(H2O) (3),[In8(HPO3)14]·(H2O)6·(C3N2H5)3·(H3O) (4) and [In8(HPO3)14]·(H2O)6·(C4N2H11)3·(H3O)·(H2O)2) (5), with same framework, have been prepared hydrothermally using ethylenediamine, imidazole, triethylene tetramine, piperazine as the template, respectively, in the system containing F- anion. The experimental results show that compound 3, 4 and 5 have the same framework, and can be obtained under similar conditions using different organic templates. The compound 3 crystallizes in the triclinic system and space group P-3, and the compound 4, 5 crystallize in the triclinic system and space group P-3cl. Their frameworks may be seen to consist of octahedral InO6 and pseudo pyramidal HPO3, which form the layers containing 4-, 6-member rings along c axis direction,and the layers are pillared through additional InO6 octahedra to produce a three-dimensional framework with 12-menber ring windows along a and b axes directions, respectively. The protonal organic amine exists between the channels and balances the negative charge. 4. Two 3-D inorganic framework indium phosphites, In2(HPO3)3 (6) and In2(HPO3)3(H2O) (7), have been prepared hydrothermally using imidazole, 1,6-Hexanediamine as structure-directing agents, respectively. The compound 6 crystallizes in the triclinic system and space group P-3; and the compound 7 crystallizes in the monoclinic system and space group P21. The structure of compound 7 was reported ago. Two compounds all have the dimers, which contain unusual In-O-In bonds, but compound 6 has the dimer In2O9 with three In-O-In bonds and compound 7 has the dimmer In2O10 with two In-O-In bonds. Their frameworks are different because of different dimers.5. Two 3-D inorganic framework indium phosphates, InPO4·2H2O ( 8 and 9), have been prepared hydrothermally using 1,6-Hexanediamine, 2-aminopyridine as structure-directing agents, respectively. Two compounds have the same empirical formula anf different structure, which were reported ago, because their bond lengths and angles are different.In conclusion, it is found from the results obtained that the microporous compounds of indium phosphites can be prepared by hydrothermal method using appropriate organic amine as template or structure-directing agent. And indium phosphites are difficult to be synthesized because of longer In radius. The known structure of indium phosphates and phosphites often occur in preparation of new compounds because In has only octahedral form.