First structural determination of layered and pillared organic derivatives of γ-zirconium phosphate by X-ray powder diffraction data

Formation of Layered Proton-Conducting Zirconium and Titanium Organophosphonates by Topotactic Reaction: Physicochemical Properties, Proton Dynamics, and Atomic-Resolution Structure

A series of new zirconium and titanium phosphates-organophosphonates, in which the organophosphonate moiety is functionalized with a sulfo group, was prepared by a topotactic reaction involving the gamma modification of zirconium or titanium hydrogen phosphate with 2-bis(phosphonomethyl)amino-ethan-1-sulfonic acid (H₄TDP). H₄TDP represents a new type of functionalizing agent, which can be easily prepared by a Moedritzer-Irani reaction from taurine (2-aminoethanesulfonic acid). The gamma modification of zirconium hydrogen phosphate (γ-ZrP) with H₄TDP provides mixed phosphate-organophosphonate compounds with the formula Zr(PO₄)(H₂PO₄)_1-2x(H₂TDP)_x·yH₂O, where x = 0.15, 0.34, 0.45, and is controlled by the γ-ZrP/H₄TDP ratio in the starting mixture. On the contrary, by the topotactic gamma modification of titanium hydrogen phosphate (γ-TiP) with H₄TDP, only one product with the formula Ti(PO₄)(H₂PO₄)_1-2z(H₂TDP)_z·yH₂O, where z = 0.41 ± 0.01, was obtained regardless of the composition of the starting mixture. The synthesized compounds were characterized by elemental analysis, thermogravimetric analysis, energy-dispersive X-ray analysis, and infrared spectroscopy. The way the topotactic reaction proceeds and how the grafted organophosphonate groups are bonded to the layers of the host structure were suggested on the basis of the solid-state NMR data. It was found that the grafted moieties are spread evenly in the host layers among the hydrogen phosphate groups. The obtained solids are able to intercalate basic molecules, as was proved by the intercalation reactions of the zirconium series with butylamine. The amount of intercalated butylamine increases with increasing x. It is known that both host compounds, γ-ZrP and γ-TiP, are protonic conductors. It was found that the incorporation of H₂TDP increases conductivity of the zirconium compound when x = 0.15, but further incorporation of H₂TDP into the γ-ZrP host structure leads to a decrease of conductivity. This behavior is explained on the basis of the ¹H MAS and the ¹H-¹H EXSY NMR data.

Phosphonate-substituted zirconium oxo clusters

ABSTRACT

The phosphonate-substituted zirconium oxo clusters Zr6O2(OBu)12(O3PPh)4 and Zr7O2(OiPr)12(O3PCH2CH2CH2Br)6, with octahedrally coordinated Zr atoms, were synthesized by reaction of zirconium alkoxides with phosphonic acid bis(trimethylsilyl) esters. The basic structural motif are Zr3O(µ2-OR)3(OR)3 units which are connected in different ways.

GRAPHICAL ABSTRACT

A comparative structural study of alkane- α,ω-diphosphonic acids

In a comparative structural study, the solid state structures within the homologous series of alkane-α,ω-diphosphonic acids, H2O3P–(CH2) n –PO3H2 with n = 6–12, have been characterised by powder and single crystal X-ray diffraction. The crystal structures of the odd-numbered diphosphonic acids were found to be homotypic. For the even-numbered diphosphonic acids – including the two already known polymorphs of butane-1,4-diphosphonic acid – two different types are found. Basically, all alkane-α,ω-diphosphonic acids exhibit pillared-layered structures with their terminal groups forming two-dimensional hydrogen bonded networks which are covalently bridged by alkylene chains. Structural differences occur within the hydrogen bonding systems as well as in the arrangement of the alkylene chains. Based on the existence of different structure types of the alkane-α,ω-diphosphonic acids, the progression of their melting points can be explained.

Structural diversity and chemical trends in hybrid inorganic–organic framework materials

Hybrid framework compounds, including both metal-organic coordination polymers and systems that contain extended inorganic connectivity (extended inorganic hybrids), have recently developed into an important new class of solid-state materials. We examine the diversity of this complex class of materials, propose a simple but systematic classification, and explore the chemical and geometrical factors that influence their formation. We also discuss the growing evidence that many hybrid frameworks tend to form under thermodynamic rather than kinetic control when the synthesis is carried out under hydrothermal conditions. Finally, we explore the potential applications of hybrid frameworks in areas such as gas separations and storage, heterogeneous catalysis, and photoluminescence.

Anionic Ligand Exchange on ZrPO4Cl(dmso): Alkoxide and Carboxylate Derivatives

This paper reports the preparation and characterization of a series of organic derivatives of ZrPO(4)Cl(CH(3))(2)SO obtained by topotactic anion exchange of chloride ligands with several n-alkoxide (RO) and carboxylate groups (RCOO). Exchange with alkoxides, with an alkyl chain length from 2 to 8 carbon atoms, gave products of general formula ZrPO(4)RO(CH(3))(2)SO. In these derivatives alkoxide groups, covalently bonded to zirconium atoms via Zr-O bonds, point toward the interlayer region. Carboxylate derivatives, of general formula ZrPO(4)[(RCOO)(CH(3))(2)SO](1)(-)(x)(OH H(2)O)(x), were obtained using benzoate (x = 0), nitrobenzoate (x = 0.3), and phenylacetate (x = 0.2) groups. The thermal behavior of these organic derivatives is discussed. Due to this reactivity, ZrPO(4)Cl(CH(3))(2)SO is an attractive precursor for materials chemistry.

Preparation, characterization, and structure of zirconium fluoride alkylamino-N,N-bis methylphosphonates: a new design for layered zirconium diphosphonates with a poorly hindered interlayer region

This paper reports the preparation and characterization of the homologous series of layered zirconium fluoride n-alkylamino-N,N-bis methylphosphonates, of general formula ZrF(O(3)PCH(2))(2)NHC(n)H(2n+1) (n = 1, 2, 3, 4, 5, 6, 8, 9, 10), in which the two phosphonic groups of each diphosphonate building block participate in the assembly of a single lamella, because they are joined to zirconium atoms belonging to the same layer. The crystal structure of one of the series of these zirconium diphosphonates, ZrF(O(3)PCH(2))(2)NHC(5)H(11), has been solved "ab initio" by X-ray powder diffraction data. The structure is monoclinic, space group P2(1)/c. The zwitterionic character of the diphosphonate moiety is a distinctive feature which acts as a structure-orienting factor, generating a layer framework which is different from the other structures known for zirconium phosphates and phosphonates. This compound undergoes a phase transition at 117 degrees C which involves a rearrangement of the interlayer alkyl chains. The structure of the high-temperature phase has been refined by the Rietveld method. Because only one organic residue is associated with two phosphonate tetrahedra, a poorly hindered interlayer region is formed, and alkyl chains bonded to adjacent layers are interdigitated. Preliminary experiments have shown that these compounds are able to intercalate organic molecules, such as n-alkanols, from very dilute water solutions.

Synthesis, characterization, and crystal structures of two divalent metal diphosphonates with a layered and a 3D network structure

Reactions of N-methyliminobis(methylenephosphonic acid), CH(3)N(CH(2)PO(3)H(2))(2) (H(4)L), with divalent metal acetates under different conditions result in metal diphosphonates with different structures. Mn(H(3)L)(2).2H(2)O (complex 1) with a layer structure was prepared by a layering technique. It is triclinic, P1 macro with a = 9.224(3) A, b = 9.780(3) A, c = 10.554(3) A, alpha = 82.009(6) degrees, beta = 74.356(6) degrees, gamma = 89.853(6) degrees, Z = 2. The Mn(II) ion is octahedrally coordinated by six phosphonate oxygen atoms from four ligands, two of them in a bidentate and two in a unidentate fashion. Each MnO(6) octahedron is further linked to four neighboring MnO(6) octahedra through four bridging phosphonate groups, resulting in a two-dimensional metal phosphonate (002) layer. These layers are held together by strong hydrogen bonds between uncoordinated phosphonate oxygen atoms. The zinc complex Zn(3)(HL)(2) (complex 2) was synthesized by hydrothermal reactions (4 days, 438 K, autogenous pressure). It is monoclinic, P2(1)/n with a = 7.7788(9) A, b = 17.025(2) A, c = 13.041(2) A, beta = 94.597(2) degrees, Z = 4. The structure of complex 2 features a 3D network built from ZnO(4) tetrahedra linked together by bridging phosphonate groups. Each zinc cation is tetrahedrally coordinated by four phosphonate oxygen atoms from four ligands, each of which connects with six zinc atoms, resulting in voids of various sizes. Magnetic measurements for the manganese complex shows an antiferromagnetic interaction at low temperature. The effect of the extent of deprotonation of phosphonic acids on the type of complex formed is discussed.