Friday, May 30, 2008

ASAP Chem. Mater., ASAP Article,

Characterization of Layered γ-Titanium Phosphate (C2H5NH3)[Ti(H1.5PO4)(PO4)]2·H2O Intercalate: A Combined NMR, Synchrotron XRD, and DFT Calculations Study
Luís Mafra* and João Rocha*

Organically templated titanium phosphate, (C2H5NH3)[Ti(H1.5PO4)(PO4)]2·H2O, has been prepared by hydrothermal synthesis from titanium(IV) chloride, phosphoric acid, and ethylamine. The structure of this material has been characterized by synchrotron X-ray powder diffraction, 1H, 13C, 15N, and 31P (including 1H{FS-LG}-1H HOMCOR, 1H{FS-LG}-31P HETCOR, 1H-1H DQ-SQ, 13C{31P} REDOR) MAS NMR, and FTIR spectroscopies and thermal analyses (TG and DSC). Its triclinic structure was solved in the space group P1 (No. 1) with the following final unit cell parameters: a = 5.1126(1), b = 6.3189(2), c = 12.0396(5) Å, α = 100.931(2), β = 97.211(2), γ = 90.683(3)°, and V = 378.62(2) Å3 (Z = 1). This pseudo-three-dimensional compound is built up of anionic titanium phosphate layers, similar to those present in the γ-type titanium phosphate, and ethylammonium cations residing in the interlayer one-dimensional channels. On the basis of empirical (particularly NMR and powder XRD) and theoretical (DFT calculations using plane waves basis set) data, the 1H NMR spectrum has been assigned, and evidence was found for a very strong interlayer P−O···H···O−P interaction.

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