Hydrothermal Synthesis And Charaterization Of Mn(Ⅱ)-substituted Aluminophosphates And Manganese Phosphates

Inorganic microporous materials have popular application in catalysis,adsorption, ion-exchange, separation and host-guest assemblies due to their uniquepore architectures. And the rational design and synthesis of new microporouscompounds, as well as the development of new synthetic ways are becoming thecentral topic of microporous materials chemistry. In the last decade, the synthesis ofnew materials that might combine the nanoporosity of zeolites with the magnetic andoptical properties, electronic conductivity and ferrodlectricity of transition metalphosphates such as MnPOs, VPOs, FePOs, ZnPOs and CoPOs have been reported inthe literature. Many of these materials exhibit unique structures and may havepotential applications in catalysis and magnetic field.This research is focused on the hydrothermal synthesis and structuralcharacterization of Mn(II)-substituted aluminophosphates and manganese phosphatestemplated by organic amine. Main results conclude:1. The MnAPO-14 has been synthesized hydrothermally in the presence of theDABCO template molecules. The MnO4(H2O)2 octahedra, AlO4 terahedra and PO4terahedra cross-link to form the 3-D open-framework [MnAl3P4O18H4]2-withdiprotonated DABCO template molecules located in the channels compensating thenegative charges. Its framework is analogous to aluminophosphate zeotype AFN inwhich 25% of the aluminum sites are replaced by Mn(II) atoms. This work suggeststhat the host-guest charge-density matching principle determines not only theconcentration of transition-metal ions but also the substitution sites in zeolitetopology.2. A Mn(II)-substituted aluminophosphate compound MnAPO-14-PDA has beensynthesized hydrothermally in the presence of the 1,3-PDA as the structure-directingagent. The linkages of MnO5 trigonal pyramidals, AlO6 octahedra, AlO4 and PO4terahedra form the 3-D open-framework [MnAl3P4O17]3-with diprotonated 1,3-PDAtemplate molecules and protonated H2O molecules located in the 8-MR channelscompensating the negative charges. Its framework is analogous toMnAPO-14-DABCO with zeotype AFN topology in which 25% of the aluminumsites are replaced by five-coordinated Mn(II) atoms. Our work demonstrate that thehost-guest interaction determines not only the substitution sites but also thecoordination modes of Mn(II) atoms in aluminophsphate zeolite frameworks.3. A Mn(II)-substituted aluminophosphate compound MnAPO-GIS has beensynthesized hydrothermally in the presence of the isopropylamine as thestructure-directing agent. The linkages of MnO4/AlO4 and PO4 tetrahedra form the3-D open-framework [MnAl2(PO4)3]-with the protonated distorted isopropylaminemolecules. Its structure is analogous to aluminophosphate with zeotype GIS topology.in which 33% of the aluminum sites are replaced by Mn(II) atoms.4. A three-dimensional an Manganese(II)-Substituted Aluminum PhophateMn3Al6(PO4)12·4tren·11H2O (noted compound MnAPO-tren and tren istris(2-aminoethyl)amine), has been synthesized hydrothermally. Theopen-framework built up from strict alteration of TO4/AlO4 and PO4 tetrahedrathrough corner-sharing vertex oxygen atoms. It contains 12-membered ring channels.The Mn atoms of the framework is bivalence proved by magnetic susceptibilitymeasurements, and the Mn2+ ions have no magnetism interactions, in agreement withthe fact that all the Mn(II)O4 are isolated, e. g. linked through the PO4 tetrahedra.5. A family of new lamellar manganese phosphates, designated MnPO-Ln,MnPO-DETA, MnPO-CHA, respectively, have been hydrothermally synthesized inthe present of long-chain primarily amines (amines: CnH2n+1NH2, n = 4, 6, 8) ordiethyltriamine or cyheylamine. In the structure of MnPO-Ln, the double layers ofn-butylamine, n-hexylamine and n-octylamine molecules are sandwiched by themanganese phosphate layers, respectively. Magnetic measurements show that theMn2+ ions in MnPO-L4 is mainly antifferromagnetic interactions. Because of thelimitation of the size of the crystals, we can not get the detailed information abouttheir structure, while the suitable synthesis routes lead to the even more lamellarmanganese phosphate.6. A two-dimensional layered manganese (II) pyrophosphate,[NH4]2[Mn3(P2O7)2(H2O)2] (MnPO-NH4), has been synthesized hydrothermally. Itsstructure is built up by MnO6 octahedra and P2O7 units, with ammonium NH4 +cations residing in the interlayer region. The manganese pyrophosphate layer consistsof infinite chains of cis and trans edge sharing MnO6 octahedra linked by P2O7 units.Magnetic susceptibility measurements show that this compound exhibitsferrimagnetic-like ordering below 3.2 K. Furthermore, magnetic exchange occurswithin the manganese-oxygen zigzag chains via the oxygen anions. There are twopossible superexchange pathways within these chains. The competition between twoopposite coupling interactions results in the ferromagnetic magnetism.7. A layered manganese (II) phosphate, Mn6(H2O)2(HPO4)4(PO4)2·C4N2H12(MnPO-PiP), has been synthesized hydrothermally in the present of pip. Itsstructure resembles to a manganese phosphate characterized by synchrotron powderX-ray diffraction. Differently from the P-1 space group, the MnPO-PiP have thehigher symmetry of C2/c. Magnetic measurements show that the Mn2+ ions inMnPO-L4 is mainly antifferromagnetic interactions. It is noted that water solvationcould lead to the lamellar framework easily. So the partially noaqueous media ispreferred.