New Multifunctional Lanthanide and Zr(IV) Phosphonates Derived from the 5-(dihydroxyphosphoryl) Isophthalate Ligand as Proton Conductors

Metal phosphonates are essentially acidic solids featured by groups such as P-OH, -COOH, etc. Moreover, the presence of coordination and lattice water molecules favors the formation of H-bond networks, which make these compounds appropriate as proton conductors, attractive for proton exchange membranes (PEMs) of fuel Cells.1 We report here, general characteristics of metal phosphonate derivatives composed of the polyfunctional 5-(dihydroxyphosphoryl) isophthalate ligand2 and lanthanides or zirconium ions. In the case of the lanthanide derivatives, crystalline compounds were synthesized under hydrothermal conditions. Preliminary results suggest that at least three isostructural series of compounds are formed. One of them, with La3+ derivative as prototype, is characterized by an orthorhombic unit cell (a = 12.7745(6) Å, b = 11.8921(4) Å, c = 7.2193(5) Å). Pr3+, Eu3+ and Gd3+ compounds, displays a monoclinic unit cell likewise the Yb3+ solid, the latter exhibiting different crystallographic parameters. Zr(IV) = compound, with formula Zr[(HO3P-C6H3-(COO)2H)2]·8H2O; was obtained at 80 ºC in the presence of HF as mineralizing agent. This solid crystallizes in an orthorhombic unit cell (a = 21.9306 Å, b = 16.6169 Å, c = 3.6462 Å). All these compounds contain in their frameworks water molecules that contribute to the formation of H-bond networks, making them prone as proton conductor candidates. Structural and proton conductivity are underway.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Plan Propio de Investigación de la UMA MAT2016-77648

Synthesis and properties of novel lanthanide carboxyphosphonates

Metal phosphonates are essentially acidic solids featured by groups such as P-OH, -COOH, etc. The presence of bound and lattice water favors the formation of H-bond networks, which make these compounds appropriate as proton conductors, attractive for proton exchange membranes (PEMs) of Fuel Cells. Moreover, these properties can be enhanced by appropriate modification of the synthesis conditions. We report here, general characteristics of three new series of isostructural compounds resulting from the combination of the polyfunctional 5-(dihydroxyphosphoryl) isophthalate acid with lanthanide ions. All compounds were synthesized under hydrothermal conditions and their crystal structures were solved from powder X-ray diffraction data using synchrotron radiation. In contrast with Series III compounds, which exhibit a layered structure, Series I and II present pillared frameworks. All these compounds contain water molecules that contribute to the formation of H-bond networks. Upon exposure to ammonia vapour, from an aqueous solution, solid state transformations are observed which are accompanied of an enhancement of their proton conductivity properties.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

New Multifunctional Zirconium(IV) Phosphonates Derivativesas Proton Conductors and Catalysts

Coordination polymers based in phosphonic acid display a wide range of metalcoordination modes. Moreover, the existence of acidic P-OH groups in their structure, as well as of others functionalized organic group such as carboxylic or amino groups, and the presence of coordination and/or lattice water molecules favors the formation of hydrogen bond networks, make them appropriate materials as proton conductors and, therefore, attractive for proton exchange membranes of fuel cells or electrolyzers.The current interest in metal phosphonates, lies in their properties, such as high chemical and thermal stability and high insolubility. In addition, zirconium phosphonates have also been studied for specific purpose such as catalysis, ion exchange and intercalation processes, so on. In this work, we reported the synthesis, characterization and structural determination of three new zirconium phosphonates derived from the phosphonic acids: Zr-PNA (PNA = 5-(dihydroxyphosphoryl) nicotinic acid), Zr-BTMP (BTMP = 1,2,3-[phenelyenetris(methylene)]tris-phosphonic acid) and Zr-PiPthA (PiPthA = 5-(dihydroxyphosphoryl)-isophthalic acid). All zirconium derivatives were synthesized under hydrothermal conditions at 80 ºC in the presence of HF as mineralizing agent. The crystal structures of Zr-PNA and Zr-BTMP have been solved from powder X-ray diffraction data and both solid crystallize in the monoclinic system. Zr-PNA shows a 1D structure formed by chains of ZrO4F2 octahedra bridged by the phosphonates groups of the ligand, while Zr-BTMP exhibits a 3D framework formed by double chains of isolated ZrO6 octahedra bridged by the different phosphonates groups of the ligand. Compound Zr-PiPthA,crystallizes in an orthorhombic unit cell (a = 21.9306 Å, b = 16.6169 Å, c = 3.6462 Å). Their structural features, proton conductivity and ion exchange properties as well as their catalytic behavior toward the one-pot transformation of furfural to other bio-products reaction will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Proyectos I+D+i nacionales MAT2016-77648-R y PID2019-110249RB-I00 del MICINN. Grupo de investigación FQM-113 y Proyecto I+D+i de la Junta de Andalucía PAIDI2020- DOC_00272

Design, synthesis and noncentrosymmetric solid state organization of three novel pyridylphosphonic acids

Three pyridylphosphonic acids, 3-pyridylphosphonic acid 1, 5-(dihydroxyphosphoryl)nicotinic acid 2, and 3,5-pyridinediyldiphosphonic acid 3, were synthesized and structurally investigated by solid state FT-IR and single crystal X-ray diffraction methods