Characterization of Layered γ-Titanium Phosphate (C 2 H 5 NH 3 )[Ti(H 1.5 PO 4 )(PO 4 )] 2 · H 2 O Intercalate: A Combined NMR, Synchrotron XRD, and DFT Calculations Study Luı ´s Mafra* and Joa ˜o Rocha* Department of Chemistry, CICECO, UniVersity of AVeiro, 3810-193 AVeiro, Portugal Christian Fernandez Laboratoire Catalyse et Spectrochimie (CNRS UMR 6506), ENSICAEN and UniVersite ´ de Caen-Basse Normandie, 14050 Caen, France Germa ´n R. Castro SpLine, Spanish CRG Beamline, ESRF, BP 220, F-38043 Grenoble Cedex, France Santiago Garcı ´a-Granda, Aranzazu Espina, Sergei A. Khainakov, and Jose ´ R. Garcı ´a Departamentos de Quı ´mica Fı ´sica y Analı ´tica y Quı ´mica Orga ´nica e Inorga ´nica, UniVersidad de OViedo, 33006 OViedo, Spain ReceiVed January 17, 2008. ReVised Manuscript ReceiVed March 7, 2008 Organically templated titanium phosphate, (C 2 H 5 NH 3 )[Ti(H 1.5 PO 4 )(PO 4 )] 2 · H 2 O, 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, 1 H, 13 C, 15 N, and 31 P (including 1 H{FS-LG}- 1 H HOMCOR, 1 H{FS-LG}- 31 P HETCOR, 1 H- 1 H DQ-SQ, 13 C{ 31 P} 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, R) 100.931(2),  ) 97.211(2), γ ) 90.683(3)°, and V ) 378.62(2) Å 3 (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 1 H NMR spectrum has been assigned, and evidence was found for a very strong interlayer P-O ··· H ··· O-P interaction. Introduction γ-Titanium phosphate compounds intercalated with n- alkylamine may be used as precursors in pillaring reactions, because of their water stability, suitable interlayer distance, moderate affinity of the intercalated species toward the host active centers, and an adequate occupied interlayer volume. 1–3 Despite the many potential applications of these materials, 4,5 their structural features have remained poorly understood. Recently, we have combined chemical information, NMR spectroscopy, powder XRD data, and chemical modeling studies to propose the first crystal structure of a n-alkylamine templated γ-titanium phosphate, (C 6 H 13 NH 3 )[Ti(HPO 4 )- (PO 4 )] · H 2 O. 6 Although X-ray powder diffraction provides direct infor- mation on the crystal structure, it is not suitable to elucidate the local environment of 1 H nuclei. Probing 1 H environments is important to study intercalation compounds because of the presence of hydrogen bonding networks involving the guest molecules (alkylamine and water) and dihydrogen- phosphate groups located on the surface of the γ-titanium phosphate layer. Solid-state NMR probes the local environ- ment of a given nucleus and does not depend on the particle size or crystallinity of the material. Surprisingly, few NMR studies have been reported on γ-titanium phosphate inter- calates, 6 except for the use of routine 31 P NMR to study the phosphate layer. 7 Because of strong 1 H- 1 H dipolar couplings, recording high- resolution 1 H NMR spectra of organic-inorganic hybrid * Corresponding author. E-mail: lmafra@ua.pt. (1) Mene ´ndez, A.; Ba ´rcena, M.; Jaimez, E.; Garcı ´a, J. R.; Rodrı ´guez, J. Chem. Mater. 1993, 5, 1078. (2) Espina, A.; Parra, J. B.; Garcı ´a, J. R.; Pajares, J. A.; Rodrı ´guez, J. Mater. Chem. Phys. 1993, 35, 250. (3) Espina, A.; Jaimez, E.; Khainakov, S. A.; Trobajo, C.; Garcı ´a, J. R.; Rodrı ´guez, J. Chem. Mater. 1998, 10, 2490. (4) Alberti, G.; Costantino, U. Inclusion Compounds. Inorganic and Physical Aspects of Inclusion; Oxford University Press: Oxford, 1991; Vol. 5. (5) Alberti, G.; Casciola, M.; Costantino, U. AdV. Mater. 1996, 8, 291. (6) Mafra, L.; Paz, F. A. A.; Rocha, J.; Espina, A.; Khainakov, S. A.; Garcia, J. R.; Fernandez, C. Chem. Mater. 2005, 17, 6287. (7) Bortun, A.; Jaimez, E.; Llavona, R.; Garcı ´a, J. R.; Rodrı ´guez, J. Mater. Res. Bull. 1995, 30, 413. 3944 Chem. Mater. 2008, 20, 3944–3953 10.1021/cm800165p CCC: $40.75  2008 American Chemical Society Published on Web 05/24/2008