Synthesis and physicochemical study of nanocrystalline magnesium-containing calcium hydroxylapatites and chitosan

The interaction in the CaCl₂-MgCl₂-(NH₄)₂HPO₄-NH₃-H₂O and CaCl₂-MgCl₂-(NH₄)₂HPO₄-(C₆H₁₁NO₄) _n -NH₃-H₂O systems at 25°C has been investigated by the solubility (Tananaev’s residual concentration) method and by pH measurements. Magnesium-containing calcium hydroxylapatites with the general formula Mg _x Ca_{10 − x} (PO₄)₆(OH)₂ · nH₂O (x = 0.05, 0.1, 0.2, 0.3; n = 6–7.3) and magnesium- and chitosan-containing calcium hydroxylapatites with the general formula Mg _x Ca_{10 − x} (PO₄)₆(OH)₂ · y(C₆H₁₁NO₄) · nH₂O (x = 0.05, 0.1, 0.2, 0.3; y = 0.1, 0.3, 0.46; n = 6–8.3) have been isolated in the nanocrystalline state. The solids have been characterized by chemical and thermogravimetric analyses, X-ray diffraction, and IR spectroscopy.     

Synthesis and Physicochemical Study of Chitosan-Containing Calcium Hydroxylapatites

The CaCl₂-(NH₄)₂HPO₄-(C₆H₁₁NO₄)_n-NH₃-H₂O system at 25°C was studied by the solubility (Tananaev’s residual concentrations) technique and pH measurements. The parameters providing for the coprecipitation of nanocrystalline (12.5–18.7 nm) calcium and chitosan hydroxylapatites were found. Calcium-deficient chitosan hydroxylapatites Ca_9.8(PO₄)₆(OH)_1.6 · xC₆H₁₁NO₄ · yH₂O, where x = 0.075 or 0.37 and y = 5.8 or 6.2, and stoichiometric calcium hydroxylapatites Ca₁₀(PO₄)₆(OH)₂ · xC₆H₁₁NO₄ · yH₂O, where x = 0.075, 0.1, 0.2, 0.37, 0.5, or 0.75 and y = 5.7–7.5, were synthesized. Solid phases were characterized by chemical analysis, X-ray powder diffraction, thermogravimetric analysis, and IR spectroscopy.     

Synthesis and physicochemical characterization of nanocomposites of calcium hydroxylapatite-chitosan-multiwall carbon nanotubes

The synthesis and physicochemical characterization of nanocomposites of calcium hydroxylapatite-chitosan-multiwall carbon nanotubes (CNTs) was performed. The CaCl₂-(NH₄)₂HPO₄-(C₆H₁₁NO₄) _n -CNT-NH₃-H₂O system was studied by the solubility (Tananaev’s residual concentration) method and pH measurements at 25°C. Conditions for the joint precipitation of nanocrystalline calcium hydroxylapatite, chitosan, and multiwall CNTs were found. Nanocomposites with the general formula Ca₁₀(PO₄)₆(OH)₂ · x(C₆H₁₁NO₄) · yCNT · zH₂O, where x = 0.1, 0.2, and 0.5; y = 0.5, 2.0, 4.0, and 5.0; and z = 5.9–7.9. The solid phases were characterized by chemical, thermogravimetric, and X-ray diffraction analysis and IR spectroscopy.     

Nanocrystalline Calcium Carbonate Hydroxyapatites Containing Multiwall Carbon Nanotubes: Synthesis and Physicochemical Characterization

Nanocomposites (NCs) based on carbonated calcium hydroxyapatite (CHA) (bioapatite, an analogue of the inorganic component of mammalian bone tissue), carbonate apatite (Ca₁₀(PO₄)₆CO₃, CA), and multiwall carbon nanotubes (CNTs) are prepared in the system CaCl₂–(NH₄)₂HPO₄–NH₄HCO₃–NH₃–CNT–H₂O (25°C) by coprecipitation of calcium and phosphorus salts with CNTs from aqueous solutions. The physicochemical properties of nanocomposites are studied as dependent on their formation conditions and composition using the solubility (residual concentrations) method and pH measurements. The composition, crystal structure, morphology, spectroscopic and thermal characteristics of the synthesized CHA/CNT and CA/CNT NCs are determined using chemical analysis, X-ray powder diffraction, thermal analysis, and IR spectroscopy. Either CHA/CNT NCs of composition Ca₁₀(PO₄)₆(CO₃)_x(OH)_2–2х · yCNT · zH₂O, where х = 0.2; 0.5; 0.8; y = 1, 2, 3; z = 6.8–10.8, or (when х = 1) CA/CNT NCs of composition Ca₁₀(PO₄)₆CO₃ · yCNT · zH₂O, where y = 1–3; z = 6.9–10.8, are formed as the carbonate and CNT contents of the NC increase. Our results favor the understanding of the effect of carbonization and CNTs on the metabolic formation of native bone tissue apatite and can be used for the design of efficient ceramics for bone implants.     

Uranyl complexes with methyl derivatives of alicyclic dioximes

A reaction of uranyl dioxalate complexes with methyl derivatives of alicyclic ??-dioximes, 3-methyl-1,2-cyclohexanedione dioxime and 3-methyl-1,2-cyclopentanedione dioxime, was studied. The structure of (CN₃H₆)₄[(UO₂)₂(C₆H₈N₂O₂)(CO₃)(C₂O₄)₂] · (C₆H₁₀N₂O₂) · 2H₂O and NH₄(CN₃H₆)₃[(UO₂)₂(C₇H₁₀N₂O₂)(CO₃)(C₂O₄)₂] · 2H₂O based on binuclear complex anions with carbonate-dioximate fragment was studied by X-ray diffraction.     

Phase formation in the ZrO(NO3)2-H3PO4-RbF-H2O system: the PO 43? /Zr = 0.5 section

We studied phase formation in the ZrO(NO₃)₂-H₃PO₄-RbF-H₂O system along PO₄³⁻/Zr = 0.5 (mol/mol) and RbF/Zr = 1–5 (mol/mol) sections with 2–10 wt % ZrO₂ in the starting solution. We recovered amorphous rubidium oxofluorophosphatozirconate Rb₂Zr₃OF₆(PO₄)₂ · 2H₂O and the following fluorophosphatonitratozirconates: Rb₂ZrF₄(PO₄)_0.33NO₃, which forms large cubic system crystals; weakly crystallized RbZr₃OF₃(PO₄)₂(NO₃)₂ · 5H₂O; and amorphous Zr₃OF₃(PO₄)₂NO₃ · (7–8) H₂O. A shown by its IR spectrum, Rb₂ZrF₄(PO₄)_0.33NO₃ contains NO₃- and PO₄ groups that are not coordinated to zirconium, meaning that this is a triple salt ZrF₄ · Rb(PO₄)_0.33 · RbNO₃. The formula units of the RbZr₃OF₃(PO₄)₂(NO₃)₂ · 5H₂O and Zr₃OF₃(PO₄)₂NO₃ · (7–8)H₂O phases are only conventional. All compounds have been recovered for the first time.     

Synthesis and physicochemical characterization of carboxymethylcellulose-containing calcium hydroxylapatite

The CaCl₂-(NH₄)₂HPO₄-C₈H₁₁O₇Na-NH₃-H₂O system was studied at 25°C using the solubility method (Tananaev’s residual concentration method) and pH measurements. The solid phases isolated from the system were characterized using chemical analysis, X-ray powder diffraction, IR spectroscopy, and thermogravimetry. Nanocrystalline carboxymethylcellulose-containing calcium hydroxylapatites Ca₁₀(PO₄)₆(OH)₂ · xH₂O · yC₈H₁₁O₇Na with x = 6–12 and y = 0.1–0.5 were found as a result of the characterization.     

Red and yellow solvates of chloro­(2,2′:6′,2′′‐terpyridine)platinum(II) chloride and Pt⋯Pt inter­actions

Crystallization of chloro­(2,2′:6′,2′′‐terpyridine)platinum(II) chloride from dimethyl sulfoxide yields a red polymorph, [PtCl(C₁₅H₁₁N₃)]Cl·C₂H₆OS, (I), which exhibits stacking along the a axis through pairs of Pt⋯Pt(−x, −y, −z) inter­actions of 3.3155 (8) Å. The cations are further associated through close Pt⋯Pt(1 − x, −y, −z) distances of 3.4360 (8) Å. Recrystallization from water gives a mero­hedrally twinned yellow–orange dihydrate form, [PtCl(C₁₅H₁₁N₃)]Cl·2H₂O, (II), with pairwise short Pt⋯Pt(1 − x, 2 − y, −z) contacts of 3.3903 (5) Å but no long‐range stacking through the crystals. Inter­pair Pt⋯Pt(−x, 2 − y, −z) distances between cation pairs in the hydrate are 4.3269 (5) Å.     

Molybdenum Bisphosphonates with Cr(III) or Mn(III) Ions

The synthesis of Mo^VI bisphosphonates (BPs) complexes in the presence of a heterometallic element has been studied. Two different BPs have been used, the alendronate ligand, [O₃PC(C₃H₆NH₃)(O)PO₃]^4? (Ale) and a new BP derivative with a pyridine ring linked to the amino group, [O₃PC(C₃H₆NH₂CH₂C₅H₄N)(O)PO₃]^4? (AlePy). Three compounds have been isolated, a tetranuclear Mo^VI complex with Cr^III ions, (NH₄)₅[(Mo₂O₆)₂(O₃PC(C₃H₆NH₃)(O)PO₃)₂Cr]·11H₂O (Mo₄(Ale)₂Cr), its Mn^III analogue, (NH₄)_4.5Na_0.5[(Mo₂O₆)₂(O₃PC(C₃H₆NH₃)(O)PO₃)₂Mn]·9H₂O (Mo₄(Ale)₂Mn), and a cocrystal of two polyoxomolybdates, (NH₄)₁₀Na₃[(Mo₂O₆)₂(O₃PC(C₃H₆NH₂CH₂C₅H₄N)(O)PO₃)₂Cr]₂[CrMo₆(OH)₆O₁₈]·37H₂O ([Mo₄(AlePy)₂Cr]₂[CrMo₆]). In this latter compound an Anderson-type POM [CrMo₆(OH)₆O₁₈]^3? is sandwiched between two tetranuclear Mo^VI complexes with AlePy ligands. The protonated triply bridging oxygen atoms bound to the central Cr^III ion of the Anderson anion develop strong hydrogen bonding interactions with the oxygen atoms of the bisphosphonate complexes. The UV–Vis spectra confirm the coexistence in solution of both POMs. Cyclic voltammetry experiments have been performed, showing the reduction of the Mo centers. In strong contrast with the reported Mo^VI BP systems, the presence of trivalent cations in close proximity to the Mo^VI centers dramatically impact the potential solid-state photochromic properties of these compounds.     

Synthesis of continuous substitutional solid solutions M1?xNix(H2PO4)2 · 2H2O with M = Mg, Mn, Co, or Zn

New continuous substitutional solid solutions Mg_1−x Ni _x (H₂PO₄)₂ · 2H₂O, Mn_1−x Ni _x (H₂PO₄)₂ · 2H₂O, Co_1−x Ni _x (H₂PO₄)₂ · 2H₂O, and Zn_1−x Ni _x (H₂PO₄)₂ · 2H₂O (0 ≤ x ≤ 1.00) crystallizing in monoclinic space group P2₁/n have been synthesized. Their end-member is Ni(H₂PO₄)₂ · 2H₂O. Ni(H₂PO₄)₂ · 2H₂O is isostructural to magnesium, manganese, iron, cobalt, zinc, and cadmium dihydrogenphosphates. The chemical composition and the unit cell parameters have been determined for the solid solutions. Their IR spectra have been measured. Original Russian Text ? V.N. Viter, P.G. Nagornyi, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 1, pp. 19–25.     

Uranyl complexes with ethylmethylglyoxime

Uranyl complexes with ethylmethylglyoxime were studied. The structure of (CN₃H₆)₄[(UO₂)₂(CO₃)(C₂O₄)₂(C₅H₈N₂O₂)] · 1.5H₂O was determined by X-ray crystallography. The structure of the complex is binuclear with a double carbonate dioximate bridging fragment.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Synthesis,characterization, and urease inhibitory activity of two copper(II) complexes of cyclohexanecarboxylate

The crystal structures of two copper(II) complexes of the cyclohexanecarboxylate ligand, namely [Cu(C₆H₁₁CO₂)₂(H₂O)₂]·H₂O (1) and [Cu(dpyam)₂(C₆H₁₁CO₂)](NO₃)·H₂O (2) (C₆H₁₁CO₂H = cyclohexanecarboxylic acid; dpyam = di-2-pyridylamine), have been determined by single-crystal X-ray analysis. Complex 1 contains the square-planar trans-CuO₄ chromophore, while 2 shows the square pyramidal cis-distorted octahedral CuN₄OO′ chromophore. Both complexes were found to show strong inhibitory activity against jack bean urease (IC₅₀ = 1.75 and 8.57 μM for 1 and 2, respectively), when compared with acetohydroxamic acid (IC₅₀ = 63.12 μM).     

Two new coordination host frameworks for the inclusion of 4-amino-benzophenone guest molecules

The synthesis and structural characterization of novel organometallic coordination polymers are reported. The reaction of Cd(NO₃)₂ and 4,4′-bipy in CH₃OH/H₂O gave a 2D coordination network formulated as {[Cd(4,4′-bpy)₂·(H₂O)₂](NO₃)₂·4H₂O}¹⁰, which was used to capture an organic guest species (4-amino-benezopheone, C₁₃H₁₁NO (3)) to obtain {[Cd(4,4′-bpy)₂(NO₃)(H₂O)]·NO₃·(C₁₃H₁₁NO)₂} (1). Using L (L=4,4′-trimethylenedipyridine) instead of 4,4′-bipy, {[Cd(L)₂(H₂O)₂]·2H₂O·2NO₃·C₁₃H₁₁NO} (2) was synthesized, which has an interesting configuration.     

Silver-Ethynide Clusters with Oxovanadate Components

Variation of the reaction conditions with AgC??CR (R?=?Ph, ^t Bu), ^t BuPO₃H₂, (Et₄N)VO₃ and AgNO₃ as starting materials afforded three isostructural globular neutral silver(I)-ethynide clusters incorporating the [( ^t BuPO₃)₄V₄O₈]^4? unit as an integral shell component, namely {(NO₃)₂@Ag₁₆(C??CPh)₄[( ^t BuPO₃)₄V₄O₈]₂(DEF)₆(NO₃)₂}, {(NO₃)₂@Ag₁₆(C??C ^t Bu)₄[( ^t BuPO₃)₄V₄O₈]₂(DMF)₆(NO₃)₂}·DMF·2H₂O and {(NO₃)₂@Ag₁₆(C??C ^t Bu)₄[( ^t BuPO₃)₄V₄O₈]₂(DMF)₆(NO₃)₂}·{(NO₃)₂@Ag₁₆(C??C ^t Bu)₄[( ^t BuPO₃)₄V₄O₈]₂(DMF)₄(py)₂(NO₃)₂}·DMF·5H₂O, in which the central cavity of each Ag₁₆ cluster is occupied by two nitrate ions that function as a template. Furthermore, from the reaction of AgC??C ^t Bu with (NH₄)₄[V₂O₄(d,l-citrate)₂]·4H₂O, we isolated a new high-nuclearity silver(I)-ethynide cluster [(VO₄)₂@Ag₃₄(C??C ^t Bu)₂₂(NO₃)₆]·8H₂O that encapsulates a pair of templating orthovanadate ions.     

Pyridinium tetrakis(nitrato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N)cerate(III) pyridine solvate and bis(methanol-κO)tris(nitrato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N)cerium(III)

The title complexes, (C₅H₆N)[Ce(NO₃)₄(C₁₅H₁₁N₃)]·C₅H₅N or (Hpy)­[Ce(NO₃)₄(terpy)]·py, (I) (py is pyridine, C₅H₅N, and terpy is ter­pyridine, C₁₅H₁₁N₃), and [Ce(NO₃)₃­(C₁₅H₁₁N₃)(CH₄O)₂] or [Ce(NO₃)₃(terpy)(OHCH₃)₂], (II), are 11-coordinate. The coordination polyhedron of the Ce atom in (I) is irregular, while that in (II) can be described as an icosahedron with two vertices replaced by one.     

Complexes of AgI with cationic ligands: bis[(pyridylmethyl)ammonio]silver(I) salts

Bis­[(2-pyridyl­methyl)­ammonio]silver(I) trinitrate, [Ag(C₆H₉N₂)₂](NO₃)₃, (I), and bis{bis­[(4-pyridyl­methyl)­ammonio]silver(I)} hexakis­(perchlorate) dihydrate, [Ag(C₆H₉N₂)₂]₂(ClO₄)₆·2H₂O, (II), are rare examples of complexes with cationic ligands. In (I), the Ag⁺ cation has a T-shaped [2+1] coordination involving the pyridine N atoms and a nitrate O atom, while in (II) there are three independent two-coordinate Ag complex cations (two with the Ag atoms on independent inversion centres) and disordered ClO₄⁻ ions. The crystal structures reveal the role of hydrogen bonding in stabilizing these complexes.     

Phase formation in the ZrO(NO3)2-NaF(HF)-H3PO4-H2O system at 20°C

Phase formation in the ZrO(NO₃)₂-NaF(HF)-H₃PO₄-H₂O system was studied at 20°C and 2.0–14.5 wt % ZrO₂ in the initial solution along sections with molar ratios PO ₄ ^3? /Zr = 0.5 and 1.5 and also in the presence of hydrogen fluoride at Na/Zr = 1 and PO ₄ ^3? /Zr = 0.5, 1.0, and 1.5. Crystalline zirconium hydrophosphate Zr(HPO₄)₂ · H₂O, fluorozirconates Na₅Zr₂F₁₃ and Na₇Zr₆F₃₁ · 12H₂O, fluorophosphatozirconates NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O, and amorphous NaZrO_0.5F(PO₄) · 4H₂O (provisional composition) were separated at room temperature. NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O were prepared for the first time and were studied by crystal-optical, elemental, and thermal analyses, X-ray powder diffraction, IR spectroscopy, scanning electron microscopy (SEM), and X-ray microanalysis. Na₇Hf₆F₃₁ · 12H₂O was found to exist in a mixture with the hydrophosphate.     

Cation Dependent Formation of Hybrid Organic–Inorganic Frameworks Based on the Strandberg-Type Polyanion [(O2CCH2PO3)2Mo5O15]6? and Cu2+ Ions

We present the first examples of materials based on the Strandberg type polyanion [(O₂CCH₂PO₃)₂Mo₅O₁₅]⁶⁻, linked by Cu²⁺ centers via coordination to the carboxylate functions of the polyanion. Simple one-pot reaction of Rb₄KNa[(O₂CCH₂PO₃)₂Mo₅O₁₅]·H₂O with CuCl₂·2H₂O in aqueous acidic media followed by crystallization resulted in the three hybrid organic–inorganic materials {K_2.6Rb_1.4[(PO₃CH₂CO₂)₂Mo₅O₁₅Cu(H₂O)₃]·7H₂O} _n (KRb-1), {Na₂Cs₃[(PO₃CH₂CO₂)₂Mo₅O₁₅(Cu(H₂O)₂Cl)]·6H₂O} _n (NaCs-2) and {Na_2.75Rb_1.25[(PO₃CH₂CO₂)₂Mo₅O₁₅Cu(H₂O)₃]·9H₂O} _n (NaRb-3), which were characterized by single-crystal X-ray diffraction, IR, TGA and elemental analysis. All three compounds are 1:1 polymers of the polyanion and the Cu²⁺ centers are all five-coordinate with two carboxylate oxygens in a trans fashion. However, the chains in KRb-1, NaCs-2 and NaRb-3 are packed differently along b leading to different solid state structures, indicating an important role of the alkali counter cations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Dedicated to Professor Dieter Fenske on the occasion of his 65th birthday     

Triaquatris(μ‐oxydiacetato)dipraseodymium(III) pentahydrate and hexaaquatris(μ‐oxydiacetato)dineodymium(III) oxydiacetic acid solvate dihydrate

Two new complexes of the Ln₂(oda)₃·nH₂O (oda =–O₂CCH₂OCH₂CO₂–) series are reported, i.e. {[Pr₂(C₄H₄O₅)₃(H₂O)₃]·5H₂O}_n and {[Nd₂(C₄H₄O₅)₃(H₂O)₆]·C₄H₆O₅·‐2H₂O}_n. The former is isostructural with the reported La analogue, while the latter is a new structural variety within the series. Each compound exhibits two independent nine‐coordinated Ln centres showing a variety of coordination geometries.