MS19-P03 Two polymorphs of a fibrous titanium oxophosphate as repository for active metal cationsThe pioneering studies on crystalline titanium phosphates were conducted by the Alberti Lab in the University of Perugia (Italy) and emerged in the wake of the work of the Clearfield Lab (USA) on zirconium phosphates, not to mention the contributions from the Soviet school, especially the Chernukov Lab in Nizhni Nóvgorod (Russia). In this context, our group at the University of Oviedo (Spain) published its first articles on this topic at the beginning of the 1980s. In the last decades, a great variety of metal phosphates has been synthesized and characterized. These compounds exhibit a multitude of fascinating structures and the dimensionality of their inorganic framework encompasses one-dimensional chain or ladder structures, two-dimensional layers and three-dimensional structures possessing channels of different sizes . Two Ti2O(PO4)2·2H2O 3D-polymorphs (r-TiP and π-TiP) were prepared hydrothermally , and the crystal structure of two polymorphs were solved ab initio from synchrotron X-ray powder diffraction data. The topology of two fibrous materials consists of a Ti/P/O framework enclosing two different linear channels parallel to the direction of fibers growth, both containing water molecules coordinated to only one of two octahedral-coordinated independent titanium atoms. Since the synthesis of r-TiP and π- TiP, and although this compound has been the subject of much attention and studies, our renewed interest in this material broke out as a result of its measurable thermally activated nitrogen-adsorption . This behavior constitutes the first example of nitrogen-fixation by an inorganic material at above-ambient temperature. Despite of their neutral network, these compounds exhibit a surprising ability for the intra-crystalline incorporation of metal cations into their structural channels maintaining its fibrous topology. Here, we report the synthesis and characterization of metal-based materials with potential use as photoluminescent devices (europium), bioactive systems (silver), or anodes for metal-ion batteries (alkali metals).
Acknowledgments. This work was financially supported by Spanish MINECO (MAT2016-78155-C2-1-R).
 Z. Amghouz, B. Ramajo, S.A. Khainakov, I. da Silva, G.R. Castro, J.R. García, S. García-Granda, Dimensionality changes in the solid phase at room temperature: 2D→1D→3D evolution induced by ammonia sorption–desorption on zinc phosphates, Chem. Commun. 50, 6729-32 (2014).
 A.I. Bortun, S.A. Khainakov, L.N. Bortun, D.M. Poojary, J. Rodríguez, J.R. García, A. Clearfield, Synthesis and characterization of two novel fibrous titanium phosphates Ti2O(PO4)2·2H2O, Chem Mater., 9, 1805-11 (1997).
 J. García-Glez, Z. Amghouz, I. da Silva, C.O. Ania, J.B. Parra, C. Trobajo, S. García-Granda, The ability of a fibrous titanium oxophosphate for nitrogen-adsorption above room temperature, Chem Commun. 53, 2249-51 (2017).
Keywords: Titanium-phosphate, photoluminescence, metal-ion-batteries.