Layered and pillared zirconium phosphate-phosphonates and their inclusion chemistry

Organic modification of layered zirconium phosphate/phosphonate for controlled release of therapeutic inorganic ions

The present study aims to develop a layered zirconium phosphate/phosphonate (LZP) powder to control the release of therapeutic inorganic ions. Organically modified LZPs were successfully prepared with various contents of phenyl groups via a reflux method in an aqueous solution containing phosphoric and phenylphosphonic acids. Powder X-ray diffraction analysis and Fourier transform infrared spectroscopy revealed that the crystal structure of the synthesized LZP samples was identical to that of α-zirconium phosphate, even after modification. The amount of incorporated organic molecules increased with increasing molar fractions of phenylphosphonic acid in the starting composition, as determined from the thermal analysis. Cobalt ion (Co2+), a type of therapeutic inorganic ion, was incorporated into the organically modified LZP through treatment with an acetonitrile solution containing tetrabutylammonium ions, followed by treatment with an acetonitrile solution containing CoCl2. The amount of incorporated Co2+ depended on the concentration of the phenyl groups. Furthermore, the highest amount of Co2+ was incorporated in the sample (ZP-Ph-0.5) prepared with equimolar phosphoric/phenylphosphonic acid. The ZP-Ph-0.5 sample additionally showed the ability to incorporate copper or iron ions (Cu2+ or Fe3+). The incorporated ion, either Co2+ or Cu2+, was continuously released from the ZP-Ph-0.5 sample in a saline solution over a period of three weeks, whereas the release of Fe3+ was negligible. The quantity of Co2+ released was higher than that of Cu2+. The controlled release of Co2+ from the ZP-Ph-0.5 sample was also observed in a simulated body fluid that mimicked the ionic concentration of human blood plasma. These results confirm that a specific degree of phenyl modification makes LZP a candidate host material for releasing therapeutic inorganic ions.

A new challenge for nanocrystalline α-zirconium phosphate: reaction with a diepoxyalkane

New organic derivatives of α-zirconium phosphate (ZrP) were prepared by reaction of a gel of nanocrystalline ZrP with 1,2,7,8-diepoxyoctane (diepoxide), leading to the formation of P-O-C bonds. A series of compounds having composition Zr(O₃POH)_2-2x(O₃POCH₂CH(OH)(CH₂)₄CH(OH)CH₂OPO₃)_x (hereafter indicated as ZrP(dep)_x) were obtained by varying the diepoxide/Zr molar ratio in the range 0.25-1. The samples were characterized by elemental, thermal and X-ray powder diffraction analysis. The reaction turned out to be nearly quantitative, the x values of ZrP(dep)_x being in the range 0.16 to 1.0. The interlayer distance slightly increased with increasing x, going from 12.7 to 13.2 Å. Interestingly, the materials easily intercalated alkanols at room temperature, both from liquid and vapor phases; it is noteworthy that ZrP(dep)_0.30 was able to reversibly take up 42 wt% ethanol from the vapor phase, in agreement with the presence of available free space both in the interlayer and in the intercrystal region. Geometrical structural models in which the α-ZrP layers are connected by the dep chains were proposed to support the obtained results.

Hierarchically porous nanostructures through phosphonate-metal alkoxide condensation and growth using functionalized dendrimeric building blocks

Controlled titanium alkoxide mineralization in the presence of phosphonated, dendrimeric nano-building blocks provides a new family of hierarchically porous dendrimer-bridged titanium dioxide materials.

Preparation of hybrid film of polyaniline and organically pillared zirconium phosphate nanosheet by electrodeposition

α-Zirconium phosphate was chemically modified with 1,2-bis(dimethylchlorosilyl)ethane to graft organic chain, and then it was used as host material for inorganic nanosheet-polyaniline hybrid. The grafted α-zirconium phosphate was exfoliated in an acetonitrile solution with tetrabutylammonium salt and aniline. The electrodeposition in the presence of aniline was performed, and then it resulted in a formation of higher-order structure in which phosphate nanosheet was propped up by 1,2-bis(dimethylchlorosilyl)ethane with intrusion of polyaniline into the nanospace. The gravimetric capacitance of the α-zirconium phosphate without grafts and polyaniline hybrid film was around 194 F/g with the base on the amount of polyaniline mass. On the other hand, the α-zirconium phosphate nanosheet with grafts and polyaniline hybrid film provided larger capacitance of around 350 F/g in maximum. The nanospace formed by grafted phosphate nanosheet with 1,2-bis(dimethylchlorosilyl)ethane molecules gives increased amounts of polyaniline included and diffusion paths for ions.

Usual Molecules in Unusual Environments Displaying Unusual Properties

The design of porous solids of controlled molecular geometry for various applications is a challenge of enormous technological and scientific importance. The placing of organic molecules between the layers of certain inorganic salts leads to enduring, solid materials where the confinement induces the organic molecules to change their properties or even display new ones at the supramolecular level. Many years ago, Feynman asked the question ‘What would the properties of materials be if we could really arrange the atoms (molecules) the way we want them?’. Chemistry, Physics, Engineering and even Biology are nowadays highly intertwined in the pursuing of Feynman’s ambition. However, despite all the huge efforts and smart developments, the finding of new materials is as yet, for the time being, quite open a field that allows for many serendipity-driven discoveries. In this context, we have a relatively large experience in the building of supramolecular scaffolds based in laminar zirconium phosphate (ZrP) containing covalently bonded phosphonates. In this paper, a short review will be presented concerning our past achievements and recent progress in the synthesis of organic-inorganic materials based in layered ZrP.

A novel organic intercalation system with layered polymer crystals as the host compounds derived from 1,3-diene carboxylic acids

A new type of organic intercalation system using poly(muconic acid) and poly(sorbic acid) crystals as the host compounds is described. The layered polymer crystals as the host are derived from benzyl-, dodecyl-, or naphthylmethylammonium salts of (Z,Z)-muconic or (E,E)-sorbic acids by topochemical polymerization. The subsequent solid-state hydrolysis of the resulting ammonium polymer crystals provides the corresponding carboxylic acid polymer crystals. When alkylamines are reacted with poly(muconic acid) or poly(sorbic acid) crystals dispersed in methanol at room temperature for a few hours, the intercalation proceeds to give layered ammonium polymer crystals via solid-state reactions, in which the polymers maintain a layered structure throughout. The interplanar spacing value of the polymer crystals changes according to the size of the guest molecules; that is, it exactly depends on the carbon number of the alkylamines used for each reaction of poly(muconic acid) or poly(sorbic acid) crystals. The stacking structure of alkyl chains with a tilt in the intercalated alkylammonium layers exists irrespective of the chemical and crystal structures of the host polymers. The intercalation of higher alkylamines into poly(muconic acid) crystals proceeds fast and quantitatively, while the conversion is dependent on the reaction conditions such as the structure and amount of the amine and the reaction time during the intercalation with poly(sorbic acid) crystals, due to the difference in the repeating layered structures of these polymer crystals. Some functional amines are also used as the guest molecules for this organic intercalation system.

Nonlinear optically active polymeric coordination networks based on metal m-pyridylphosphonates

A family of polymeric coordination networks based on meta-pyridylphosphonate bridging ligands has been synthesized and characterized by single-crystal X-ray crystallography. Compounds [M(2)(L-Et)(4)(mu-H(2)O)] (M = Mn, 1; Co, 2; Ni, 3; L-Et = ethyl-4-[2-(3-pyridyl)ethenyl]phenylphosphonate) were obtained by hydro(solvo)thermal reactions between diethyl-4-[2-(3-pyridyl)ethenyl]phenylphosphonate (L-Et(2)) and corresponding metal salts, while [Cd(L-H)(2)], 4 (L-H is monoprotonated 4-[2-(3-pyridyl)ethenyl]phenylphosphonate), was obtained by a hydro(solvo)thermal reaction between (L-H(2)).HBr and Cd(CF(3)SO(3))(2).6H(2)O. Compounds 1-3 are isostructural and crystallize in noncentrosymmetric space group Fdd2, and they adopt a complicated 3D framework structure composed of [M(2)(L-Et)(4)(mu-H(2)O)] building units, while compound 4 adopts a centrosymmetric 3D network structure resulted from linking 1D sinusoidal cadmium phosphate chains with L-H bridging ligands. Consistent with their polar structures, compounds 1-3 exhibit powder second harmonic generation signals larger than that of potassium dihydrogen phosphate.

New open frameworks based on metal pyridylphosphonates

A family of new 1D, 2D, and 3D coordination networks based on metal-pyridylphosphonates have been synthesized under hydro(solvo)thermal conditions. Zn(3-pyridylphosphonate)(bromide), 1, adopts a 1D ladder structure, while Co(4-pyridylphosphonate)(H(2)O)(3), 2, adopts a 2D grid structure. [Cu(2)(4-pyridylphosphonate)(2)]-2H(2)O, 3, [Cd(3-pyridylphosphonate)(2)]-DMSO, 4, Cd(4-pyridylphosphonate)(2), 5, and Cd(ethyl 4-pyridylphosphonate)(2), 6, all adopt 3D framework structures. While 3 possesses open channels that are occupied by water molecules, 4 exhibits cavities that accommodate DMSO guest molecules. The present work demonstrates that interesting open frameworks can be readily synthesized on the basis of metal pyridylphosphonates. Crystal data for 1: monoclinic space group C2/c; a = 15.267(4), b = 11.903(2), c = 10.380(2) A; beta = 98.68(2) degrees; Z = 8. Crystal data for 2: monoclinic space group P2(1)/c; a = 9.634(12), b = 7.611(9), c = 11.901(1) A; beta = 97.830(2) degrees; Z = 4. Crystal data for 3: triclinic spacegroup P one macro; a = 7.464(8), b = 9.203(1), c = 11.602(2) A; alpha = 100.289(1) degrees; beta = 104.532(1) degrees, gamma = 94.569(1) degrees; Z = 2. Crystal data for 4: tetragonal space group I4(1)/a; a = 15.114(2), b = 15.114(2), c = 13.128(3) A; Z = 8. Crystal data for 5: monoclinic space group P2(1)/c; a = 8.344(2), b = 10.589(2), c = 14.384(3) A; beta = 91.77(3) degrees; Z = 4. Crystal data for 6: monoclinic space group P2(1)/n; a = 5.606(1), b = 11.198(1), c = 14.176(2) A; beta = 94.518(1) degrees; Z = 2.

Layered cobalt hydroxysulfates with both rigid and flexible organic pillars: synthesis, structure, porosity, and cooperative magnetism

The synthesis and characterization of two members of a family of porous magnetic materials is described. The structures of Co4(SO4)(OH)6(C2N2H8)0.5*3H2O and Co4(SO4)(OH)6(C6N2H12)0.5*H2O and their thermal stability can be tailored via the choice of organic pillar. The interactions between the pillaring agent and the compositionally complex inorganic layer are discussed. The influences of two pillaring agents i.e., the flexible ethylenediamine and the relatively rigid 1,4-diazabicyclo[2,2,2]octane, on thermal stability, rigidity upon guest loss, and magnetic behavior of the pillared solids are compared. The magnetism of the pillared layered cobalt hydroxides is complex due to the influences of multiple metal sites, inter- and intralayer exchange, spin-orbit coupling, and geometrical frustration. The wide variety of potential pillars, oxyanions, and possible metal substitutions at the octahedral and tetrahedral sites offers the possibility of tailoring the magnetic and porous properties of these materials.