Metal phosphates: From syntheses and structures to applications in sorption, catalysis and teeth erosion protection

As a synthetic route a hydrothermal procedure with organic amines as templates. The electronic aspects were investigated in collaboration by using Moessbauer spectroscopy. The synthesized new compounds were structurally analyzed by single crystal X-ray diffraction. The thermal properties and stability were investigated using thermogravimetry (TGA) together with X-ray powder diffractometry (XRPD) to elucidate the loss of guest molecules and the stability of the host framework. Crystals grown from the reaction of piperazinedium phosphate, (C4H12N2)(HPO4)2 with Co(II) or Ni(II) at normal pressure and temperature gave only a hydrogen-bonded framework of composition [M(H2O)6](C4H12N2)(HPO4)2 (M = Co, Ni). Also, the compound [Cu(H2PO4)2(4,4'-bipy)2(H2O)2], prepared by non-hydrothermal routes. Thus, the hydrothermal treatment of 1,3-diaminopropane or 1,4-diaminobutane with iron(III) chloride and phosphoric acid in yielded in both cases the 3-D framework {[NH4][FeIII2(OH)(PO4)2(H2O)]•H2O}n (A). The 3-D mixed-valence iron phosphate {FeII5FeIII2(PO4)2(H0.5PO4)4}n was obtained hydrothermally starting with N-methylpiperazine and FeIICl2. Compounds {[FeII(H2PO4)2(4,4'bipy) (H2O)]•H2O•4,4'-bipy}n and {[FeIII(NO3)2(4,4'-bipy)(H2O)2](OH)(H2O)}n are 1-D coordination polymers. Compounds {[C4H12N2][FeIII3(PO4)3(HPO4)(H2O)]}n (B, 3-D) and mixed-valence {[C4N2H11.6]1.5[FeIIFeIII(PO4)(H0.8PO4)2]•H2O}n (1-D) have been synthesized using a similar hydrothermal method (starting from FeIICl2). The guest species from the open-framework materials A and B together with a gallium analog of B and the literature material {[H3N(CH2)6NH3]4[Ga16(PO4)14 (HPO4)2(OH)2F7]•6H2O}n (C) could be removed (followed by TGA) with the framework proven to remain intact (by XRPD). The resulting guest-depleted open-framework showed sorption activities for different types of organic compounds. Materials B and C but not A exhibited catalytic properties in the regioselective oxidation of n-pentane to 3-pentanol.

Author dc:creator

• Abu-Shandi, Khalid Hamad

Contributors dc:contributor

• Janiak, Christoph

Repository record source_url

https://freidok.uni-freiburg.de/data/691

OAI identifier oai:identifier

oai:freidok.uni-freiburg.de:691