Syntheses, Structures And Properties Of Metal Fluorides And Metal Phosphates Templated By Cobaltammine Complexes

Inorganic microporous materials attract considerable attentions because they have potential applications in catalysis, adsorption and separation, as well as in advanced materials. Over the past few decades, employing the templating agents or structure-directing agents (SDAs), a large number of inorganic microporous materials with various structural characteristics and physical-chemical properties have been synthesized. Commonly used structure-directing agents in the synthesis are metal cations, organic amines, organic quaternary ammonium bases, and fluorine ion, etc. Recently, some zeolite structures have been prepared by using dicyclopentadienyl metal and related derivatives as SDAs. In addition, a few stable cobaltammine complexes such as Co(dien)2Cl3, Co(en)33+, and Co(tn)33+ have been used as SDAs as well, resulting in the formation of many new open-framework metal phosphate and metal oxide structures. These metal complexes mainly play the following roles in the formation of open-framework materials: (1) balancing the charge of the framework; (2) filling the void and supporting the inorganic framework; (3) directing the specified structure. Recently, our group has systematically studied the chirality transfer from the guest chiral metal complex templates to the host inorganic open frameworks, and elucidated that hydrogen bonds of host-guest are its origin.In addition, because of the cooperative behavior between metal complexes and inorganic frameworks, their assemblies may exhibit unusual physical-chemical properties, which lead more attention for the functionality of inorganic materials with the guest metal complexes.This thesis has been focused on the synthesis of new open-framework metal fluorides and metal phosphates by using cobaltammine complexes as the SDAs, and investigation of structure-directing effect of cobaltammine complexes in the synthesis. Furthermore, the unusual physical-chemical properties of as-prepared compounds have been studied.Employing chiral cobaltammine complexes as the templates, a family of metal fluorides, [Co(en)3]2(Zr2F12)(SiF6)·4H2O (A), [Co(chxn)3](ZrF6)Cl·3.5H2O (B), [Co(en)3](Ti2F11) (C) and [Co(en)3](Zr2F11H2O) (D), containing H-bonded assemblies of discrete cobaltammine complex cations and metal fluoride anions have been successfully synthesized under hydrothermal/solvothermal conditions. Interestingly, they exhibit unusual photoelectronic effects in the near-UV region. The mechanism of these effects is investigated by use of Scaning Kelvin probe. The studies suggest that cooperative behaviors between discrete cobaltammine complex and metal fluoride ions through interactions might be responsible for these unexpected photoelectric phenomena. The fact that the signal of the surface photovoltage of each compound coincidents with one of the UV/Vis absorption transitions of the cobaltammine complex implies that a charge transfer from the excited cobaltammine complex cation to the metal fluoride anion may occur upon illumination. Photofunctional materials are important because of their unique optical and electrical properties. In contrast to conventional oxide semiconductors, there has been little investigation of the photoelectronic properties of molecular solids. This work will open-up new vistas in the search for molecular solids with useful photoelectric property.In addition, a number of new open-framework metal phosphates have been successfully synthesized under hydrothermal/solvothermal conditions by using cobaltammine complexes as the SDAs. A new layered zirconium phosphate |Co(dien)2|[Zr4H8P5O26]·4H2O (ZrPO-CJ37) has been synthesized hydrothermally by using a racemic mixture of a chiral cobaltammine complex Co(dien)2Cl3 as the template. ZrPO-CJ37 is the first zirconium phosphate templated by a transition-metal complex. Single-crystal X-ray diffraction analysis indicates that the inorganic layer of ZrPO-CJ37 is built up from the linkage of Zr-centered octahedra, and P-centered tetrahedra via vertex oxygen atoms forming a 4.6-net sheet. Its structure is featured by edge-sharing octahedral Zr(OM)6 (M = P, H) chains. The cobaltammine complex cations are located in the interlayer regions and interact with the host network through H-bonds. ZrPO-CJ37 exhibits unusual photoluminescence in UV-Vis spectral region. The edge-sharing octahedral Zr(OM)6 chains in the inorganic layer might be responsible for this unusual photoluminescence.A new 2-D layered indium phosphate [Co(en)3][In3(H2PO4)6(HPO4)3]·H2O has been prepared solvothermally by using a racemic mixture of chiral cobaltammine complex Co(en)3Cl3 as a template. It is the first indium phosphate compound templated by a transition-metal complex and is isostructural with GaPO-CJ14. The structure is characteristic of a structural unit composed of a pair of enantiomers of chiral [3.3.3] propellane-like structural motifs. The guest cobaltammine complexes and H2O located in the interlayer regions interact with the host network through H-bonds. The chiral [3.3.3]propellane-like structural motif has been commonly encountered in cobaltammine complex-templated metal phosphates. Structurally, it is in a good match with that of the octaherally coordinated chiral cobaltammine complex, indicating that there exists a stereo-specific correspondence between the host network and the guest metal complexes.A novel gallium phosphate Ga3P2O8(OH)3(H2O) (GaPO-CJ36) with a Ga/P ratio of 3/2 has been prepared in a hydrothermal reaction system of GaO(OH)-H3PO4-Co(chxn)3Cl3-H2O. The connection of GaO2(OH)3(H2O) octahedra, PO4 and GaO4 tetrahedra through vertex oxygen atoms forms a three-dimensional open framework with Hopeite lattice. Interestingly, its structure is composed of interesting [344484] cages, which has not been found in the known gallium phosphates. Differently from the gallium phosphates containing organic amines as the guest molecules, Co(chxn)33+ cations are not located in the framework eventually, however, the cobaltammine complex plays an important role in the synthesis of GaPO-CJ36. In summary, a family of new open-framework metal fluorides and metal phosphates has been synthesized by using cobaltammine complexes as the SDAs under hydrothermal/solvothermal conditions. These compounds exhibit interesting structure architectures (e.g. with chiral characteristics) and physical-chemical properties (e.g., photoelectronic effects and photoluminescence). This research will be important for the design and synthesis of chiral and photo-functional open-framework materials.