Hydrothermal preparation of the mixed titanium (IV) phosphate-phenylphosphonates and characterization of their propertie
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Hydrothermal preparation of the mixed titanium (IV) phosphate-phenylphosphonates and characterization of their properties Enrique Jaimez, Anatoly I. Bortun, and Sergei A. Khainakov Departamento de Qu´ımica Org´anica e Inorg´anica, Universidad de Oviedo, 33071 Oviedo, Spain
Igor’ I. Voitko Department of Chemistry, Kiev State Trade and Economic University, 19 Kyoto Str., 252156, Kiev, Ukraine
Jos´e R. Garc´ıaa) and Julio Rodr´ıguez Departamento de Qu´ımica Org´anica e Inorg´anica, Universidad de Oviedo, 33071 Oviedo, Spain (Received 21 January 1997; accepted 16 August 1997)
Mixed crystalline titanium (IV) phosphate-phenylphosphonates were synthesized under hydrothermal conditions using tetramethylammonium hydroxide as a templating reagent. It was found that at a relatively low molar ratio H3 PO4 : PhPO3 H2 in the reaction mixture (,1) only a pure a-titanium phenylphosphonate is formed. At the molar ratio H3 PO4 : PhPO3 H2 (3–5) : 1 the formation of a novel mixed compound titanium (IV) dihydrogenphosphate-hydrogenphosphate-phenylphosphonate takes place. Further increase of the ratio H3 PO4 : PhPO3 H2 gives mechanical mixtures of different phases. Preliminary results on the characterization of the novel compound of formula Ti(H2 PO4 )1.25 (HPO4 )0.12 (C6 H5 PO3 )1.25 ? 0.3H2 O are presented. I. INTRODUCTION
Considerable attention has been given to the layered acid salts of tetravalent metals in the last 30 years. This attention has been mainly related to their superb ion exchange behavior and high stability toward high temperature, ionizing radiation, and oxidizing reagents.1,2 These materials now have many potential applications for renal dialysis, water softening, chromatography, catalysis, inorganic membranes, and solid electrolytes.3–10 Among the layered acid salts of tetravalent metals titanium phosphates are of a special interest. Titanium phosphates can be prepared as amorphous materials, containing a variety of functional groups (H2 PO4 , HPO4 , PO4 , OH),11–13 and also as crystalline layered compounds (a-TiP and g-TiP).14–15 a-TiP has only one type of functional group, HPO4 , whereas g-TiP has H2 PO4 and PO4 groups. Their formulae could be presented as Ti(HPO4 )2 ? H2 O16 and Ti(H2 PO4 ) (PO4 ) ? 2H2 O,17 respectively. Two new layered titanium phosphates: TiO(OH) (H2 PO4 ) ? 2H2 O18 and Ti2 O3 (H2 PO4 )2 ? 2H2 O,19 containing only H2 PO4 functional groups were synthesized recently. Layered metal(IV) organophosphonates of a general formula M(RPO3 )2 have a structure similar to that of a-metal(IV) phosphates.20,21 These compounds have also attracted much attention because of the possibility of
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Address all correspondence to this author. J. Mater. Res., Vol. 13, No. 2, Feb 1998
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obtaining new materials with desired and regulated properties by changing the nature of the R group.21 The first synthesis of compounds with two types of R groups in the interlayer region (OH and C6 H5 ) was made in 1982.22 Since
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