Enzymatic hydroxyapatite as a carrier for yttrium-90 and copper and ruthenium radionuclides

The use of hydroxyapatite obtained by enzymatic synthesis (HAP_E) as a carrier of radionuclides (yttrium-90, copper(II) as a prototype of ⁶⁴Cu and ⁶⁷Cu and ruthenium-103 as a prototype of ⁹⁷Ru) is considered. The processes of sorption and desorption of ions in different solutions are compared. The sorption of copper and yttrium on HAP_E is almost irreversible, in contrast to the sorption of ruthenium, for which the reverse process depends on the medium.     

Removal of copper ions by cellulose nanocrystal-based hydrogel and reduced adsorbents for its catalytic properties

Cellulose - Removal of copper ions (Cu(II)) efficiently from water is crucial for water environment security. We use sustainable, low-cost, renewable cellulose derivatives (carboxymethylcellulose...     

Complexing properties ofSchiff bases with copper and nickel ions

Summary The solution properties ofPPP,QPP, and their complexes with copper and nickel were investigated. The composition and stability of the complexes have been determined using the spectrophotometric method atT=25±1 °C, constant ionic strength (I=0.5M, adjusted with KNO₃) and a volume ratio of methanol/water of =0.10 and 0.16 forPPP andQPP, respectively, due to lower solubility ofQPP. The experimental results have been fitted to the theoretical equations using the computerized iterative method of successive approximation. The influence ofpH and addition of another benzene ring to the ligand molecule has been studied. The structures of isolated solid metal complexes withQPP were investigated by infrared and mass spectroscopy. The use ofPPP andQPP as analytical reagents for spectrophotometric determinations of copper and nickel is discussed.

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Komplexbildende Eigenschaften vonSchiffschen Basen mit Kupfer- und Nickelionen

Zusammenfassung Die Eigenschaften vonPPP,QPP und ihrer Komplexe mit Kupfer und Nickel in Lösung wurden untersucht. Zusammensetzung und Stabilität der Komplexe wurde bei 25±1 °C, konstanter Ionenstärke (I=0.5M, eingestellt mit KNO₃) und einem. Methanol/Wasser-Volumenverhältnis von =0.10 und 0.16 fürPPP bzw.QPP (bedingt durch die geringere Löslichkeit vonQPP) bestimmt. Die experimentellen Ergebnisse wurden mittels eines Algorithmus zur sukzessiven Approximation an die theoretischen Gleichungen angepaßt. Der Einfluß despH-Werts und eines weiteren aromatischen Rings am Liganden wurden studiert. Die Strukturen der isolierten festen Komplexe mitQPP wurden mittels IR- und Massenspektroskopie untersucht. Die Verwendung vonPPP undQPP als analytische Reagenzien zur spektrophotometrischen Bestimmung von Kupfer und Nickel wird diskutiert.

     

Microscopic study of hydroxyapatite dissolution as affected by fluoride ions

Fluoride ions play a critical role in preventing tooth decay. We investigated the microscopic effects of fluoride ions on hydroxyapatite (100) surface dissolution using in situ atomic force microscopy. In the presence of 10 mM NaF, individual surface step retraction velocities decreased by about a factor of 5 as compared to NaF-free conditions. Importantly, elongated hexagonal etch pits, which are characteristic of (100) surface dissolution, were no longer observed when NaF was present. The alteration of pit shape is more distinct at a higher NaF concentration (50 mM) where triangular etch pits evolved during dissolution. Furthermore, in a fluoride concentration typical for tap water (10 μM), we observed roughening of individual step lines, resulting in the formation of scalloped morphologies. Morphological changes to individual steps across a wide range of fluoride concentrations suggest that the cariostatic capabilities of fluoride ions originate from their strong interactions with molecular steps.     

Adsorption mechanism of polylysine on hydroxyapatite and its effect on dissolution properties of hydroxyapatite

Adsorbed amounts of poly-l-lysine (pLys) and bromide ion on hydroxyapatite (HAp) from aqueous solutions of poly-l-lysine hydrobromide, and amounts of calcium and phosphate ions liberated concurrently from HAp during the adsorption of pLys were determined at 25 degrees . The pLys was adsorbed on HAp by the mechanism of ion-exchange between its amino groups and calcium ions of HAp. The released amount of calcium ion increased, therefore, with the adsorbed amount of pLys. On the other hand, the released amount of phosphate ion first decreased and then increased after attaining a minimum with the equilibrium concentration of pLys. The analysis using an equilibrium dialysis method revealed that the released phosphate ions were mainly in the bound state to the amino groups of pLys remaining in the solution, and that the concentrations of calcium and phosphate ions free from both HAp and pLys were restricted by each other under the law of the solubility product of HAp. The first decrease in the released amount of phosphate ion was concluded to be attributed primarily to the increase in the released amount of calcium ion because pLys remaining in the solution was little in this region. When sodium hydroxide was added to the solution, the adsorbed amount of pLys increased and then slightly decreased with the equilibrium pH of the solution due to the increase or decrease of the electrostatic attractive force between the adsorbate and the adsorbent. However, conformational change in pLys around pH 10 seemed to have little effect on the adsorption.     

Preparation of amino-modified hydroxyapatite and its uranium adsorption properties

The amino-hydroxyapatite (HAP-NH₂) was synthesized by grafted amino functional groups onto hydroxyapatite. The uranium adsorption performance of HAP-NH₂ was studied under different conditions. The results indicated that HAP-NH₂ possessed high adsorption capacity (96 mg g⁻¹), wide pH values range (2–8) and fast adsorption rate (20 min). The adsorption kinetic and adsorption isotherm models of HAP-NH₂ revealed that the uranium adsorption process was belonged to chemical adsorption. Furthermore, the main forces between uranium ions and HAP-NH₂ were attributed to hydroxyl, amino and phosphorous functional groups.

     

Electrochemical deposition of a copper carboxylate layer on copper as potential corrosion inhibitor

Carboxylic acids and sodium carboxylates are used to protect metals against aqueous and atmospheric corrosion. In this paper, we describe the application of a layer of copper carboxylate on the surface of a copper electrode by means of cyclic voltammetry technique and tests which measure the corresponding resistance to aqueous corrosion. Unlike the soaking process, which also forms a film on the surface, the use of cyclic voltammetry allows one to follow the deposition process of the copper carboxylates onto the electrode. The modified electrodes have been characterised with infrared spectroscopy. In addition, the corrosion resistance of the film has been investigated using polarisation resistance and Tafel plot measurements.     

Specific features of sorption of bovine serum albumin on hydroxyapatite doped with zinc ions,and the possibilities of its use as an intermediate binding protein for heterocyclic ligands

Russian Chemical Bulletin - In order to characterize hydroxyapatite (HAP) as a possible carrier of medicinal drugs and radionuclides, the possibility of using HAP modified with zinc ions (HAP-Zn)...     

Synthesis, structural features, and color of calcium-yttrium hydroxyapatite with copper ions in hexagonal channels

Copper-containing calcium phosphates Ca_{5 ? z} Y _z (PO₄)₃Cu _x OH_{1 ? x ? z ?δ}, where x = 0, 0.1, 0.3 and z = 0, 0.5, with an apatite structure and a partial substitution of yttrium for calcium have been synthesized by a solid-phase method at a temperature of 1100–1150°C. The compounds have been characterized by X-ray powder diffraction and diffuse reflectance spectroscopy. It has been established that yttrium substitutes for calcium only in the Ca(2) position, and the occupancy of this position corresponds to the yttrium content z = 0.4–0.43. The substitution by yttrium slightly decreases the unit cell parameter of the compound (by ～0.3%) and much more considerably (by 3%) reduces the diameter of a hexagonal channel formed by Ca(2) atoms. The predominant fraction of doping copper intrudes into hexagonal channels in both unsubstituted and yttrium-substituted calcium phosphates. Unsubstituted copper-containing phosphates are pink-crimson colored, whereas their yttrium-substituted analogues have much more pale colors from nearly white to greeny beidge. The absorption bands typical for a copper-containing calcium hydroxyapatite observed in diffuse reflectance spectra are strongly suppressed in yttrium-substituted samples probably due to a decreased average oxidation number of copper.     

Adsorption properties of complexes of chitosan with copper and zinc chlorides and copper sulfate

The adsorption properties of complexes of chitosan with copper and zinc chlorides and copper sulfate with respect to n-alkanes (C₆H₁₄-C₉H₂₀) and n-alcohols (CH₃OH-C₃H₇OH) were investigated by means inverse gas chromatography in the Henry region. It was found that the capability of the chitosan complexes for dispersion interaction is somewhat less pronounced in comparison with the initial chitosan. It was shown that complexation give rises to more ordered supramolecular structures, which make for an increase in the adsorption capacity of complexes with respect to n-alcohols. The small adsorption values measured were explained by the interaction of the n-alcohols only with weakly specific OH groups, since the NH₂ group is inaccessible because of its being involved in the coordination bonding with the metal ion.     

Reaction kinetics in replacement of zinc ions by copper ions in complexes with cyclic and noncyclic tetramines

A kinetic study has been made of reactions of zinc ion replacement by copper in complexes with macrocyclic and noncyclic tetramines. The activation parameters of these processes have been determined, and reaction mechanisms are proposed. A kinetic macrocyclic effect has been found in reactions of central atom replacement in tetraazamacrocyclic complexes of zinc.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 2, pp. 175–182, March–April, 1985.     

Thermal properties of mixed-ligand magnesium complexes with beta-diketonates and diamimes as potential MOCVD precursors

The series of adducts of magnesium beta-diketonates with diamimes namely Mg(thd)₂(tmeda) 1 and four new complexes Mg(thd)₂(tmpda) 2, Mg(thd)₂(pda) 3, Mg(ptac)₂(tmeda) 4, Mg(tfac)₂(tmeda) 5 [beta-diketonates = R₁C(O)CHC(O)R₂: thd (R₁ = R₂ =  ^t Bu), ptac (R₁ =  ^t Bu, R₂ = CF₃), tfac (R₁ = Me, R₂ = CF₃); diamines = R₂N(CH₂) _n NR₂: tmeda (n = 2, R = Me), tmpda (n = 3, R = Me), pda (n = 3, R = H)] were synthesized in order to investigate the influence of both ligand types on the thermochemical properties of these compounds. The thermal behavior of the complexes in the condensed phase was investigated by thermogravimetry and differential scanning calorimetry; the thermodynamic parameters of phase transitions were determined. The saturated vapor pressure of solid complexes Mg(thd)₂(tmeda) and Mg(tfac)₂(tmeda) were measured by the transmission method giving the enthalpies and entropies of sublimation processes. The reliable thermodynamic data for compound Mg(thd)₂(tmeda) were obtained with the assistance of X-ray diffraction and the static method of saturated and unsaturated vapor pressure measurements.     

Syntheses and characterization of mixed-chelate copper(II) complexes containing different counter ions; spectroscopic studies on solvatochromic properties

Solvatochromic mixed-chelate copper(II) complexes, [Cu(Cl-acac)(diamine)]X (where Cl-acac = 3-chloroacetylacetonate ion, diamine = N,N′-dimethyl,N′-benzyl-1,2-diaminoethane and X = B(Ph)₄⁻, PF₆⁻, BF₄⁻ and ClO₄⁻), have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV-Vis and IR spectroscopies. Single crystals of [Cu(Cl-acac)(diamine)(H₂O)]PF₆, complex 2, were also characterized by X-ray diffraction. The influence of the solvent polarity and counter ions on the ν_max values of the d-d bands of the complexes have been investigated by means of visible spectroscopy. All the complexes demonstrated negative solvatochromism. A multi-parametric equation has been utilized to explain the solvent effect on the d-d transition of the complexes using SPSS/PC software. The stepwise multiple linear regression (SMLR) method demonstrated that the donor power of the solvent plays the most important role in the solvatochromism of the compounds. The relative donor power of the anions X was determined by visible spectra in the solvent dichloromethane.     

Microwave synthesis of hydroxyapatite and physicochemical study of its properties

Method for microwave liquid-phase synthesis of hydroxyapatite samples was developed. The composition of the synthesis products obtained and natural hydroxyapatite was studied by X-ray phase and X-ray fluorescence microanalysis. IR spectra were measured and the dispersity of hydroxyapatite powders obtained, their solubility in water at 20°C, and structural parameters were determined in comparison with natural hydroxyapatite and that produced by the common (“classical”) liquid-phase technique. The microwave-synthesized hydroxyapatite compares well in its properties with the biological and “classical” hydroxyapatites.     

Dimethyl selenide complexes of copper,gallium and indium halides as potential precursors for selenium-containing chalcopyrite semiconducting materials

The coordination chemistry of copper, gallium and indium halides with the simplest possible selenoether i.e. Me₂Se was investigated with the aim to use the resulting complexes as precursors for selenium-containing chalcopyrite semiconducting materials. An optimized general procedure for the high yield synthesis is described and the influence of a halide ion on the structure and solubility of these metal halide dimethyl selenide complexes are discussed. These complexes were characterized by the elemental analysis, FT-IR and ¹H NMR spectroscopy as well as single crystal X-ray structures, the later study showing them to be monomeric for gallium halides, mono- or dimeric for indium halides and either an ion-pairs or 2-D extended structure in the case of copper halides.     

Preparation and properties of anionic transition metal complexes containing triheterocarbenium ions

Summary Thermally stable anionic tetracarbonylcobalt complexes containing triheterocarbenium ions, [Co(CO)₄]^–[cation]⁺, have been synthesized by the ion exchange reaction of [Co(CO)₄]^–PPN⁺ with the corresponding carbenium ions. Similar molybdenum complexes containing cyclopentadienyl and carbonyl ligands were also prepared. The complexes were characterized by elemental analyses and by i.r. and n.m.r. spectroscopies. The ionic structures of the complexes are confirmed on the basis of their large electric conductivities.     

Electrode potential-controlled DNA damage in the presence of copper ions and their complexes.

Supercoiled (sc) DNA immobilized at the surface of a hanging mercury drop electrode was cleaved by reactive oxygen species generated by an electrochemically modulated reaction of copper ions, hydrogen peroxide and/or oxygen. The cleavage was observed in a certain potential region where redox cycling of DNA-bound Cu(II)/Cu(I) took place. In the presence of 1,10-phenanthroline the maximum efficiency of DNA cleavage was shifted to more negative potentials and the effect was enhanced.     

EPR of complexes of divalent copper ions with organophosphorus derivatives of 2-aminopyridine

The complexation of copper(II) ion with organophosphorus derivatives of 2-aminopyridine was studied with EPR. It was found that, compared with 2-aminopyridine, the presence of a P-N bond in its derivatives substantially changes the character of the coordination of the ligand with respect to divalent copper, which includes an aminic nitrogen atom in the coordination sphere of the metal, and results in the formation of a four-membered chelate ring. The parameters of the EPR spectra and evaluations of the stability constants are given.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2756–2763, December, 1990.