Syntheses,Characterization, and Crystal Structures of a Dinuclear Complex and Coordination Polymer of Mercury(II) with Schiff Base Ligands containing N3 and N4 Donors

Two dinuclear mercury(II) iodide compounds, [Hg₂(L)(I)₄] ( 1 ) and [(L′)Hg(μ‐I)₂HgI₂]_n ( 2 ) [L = N,N′‐bis(phenyl(pyridin‐2‐yl)methylene)propane‐1,2‐diamine and L′ = N‐(phenyl(pyridin‐2‐yl)methylene)propane‐1,2‐diamine] were synthesized and characterized. The molecular structures of [Hg₂(L)(I)₄] ( 1 ) and [(L′)Hg(μ‐I)₂HgI₂]_n ( 2 ), which were determined by single‐crystal X‐ray diffraction, indicate that each Hg^II in 1 has a distorted tetrahedral environment around the metal atom with a HgN₂I₂ chromophore, whereas in 2 one mercury(II) atom adopts a distorted tetrahedral arrangement with a HgI₄ chromophore and the other has a distorted square pyramidal environment with HgN₃I₂ chromophore. In the solid state, compound 2 consists of a 1D coordination polymer structure.     

Optimization of fundamental parameters in routine production of 90Y-hydroxyapatite for radiosynovectomy

Hydroxyapatite was applied as a carrier adsorbing ⁹⁰Y³⁺ ions for ⁹⁰Y-HA colloid production. The radiopharmaceutical colloid was prepared by adding an acidic solution of ⁹⁰YCl₃ to HA suspension in saline solution. Effective parameters on labeling of ⁹⁰Y-HA were evaluated. Adsorption and cation-exchange properties were studied using inductively coupled plasma elemental analysis and N₂ adsorption–desorption isotherm method. Radionuclidic purity was over 99.9 %. Labeling yield and radiochemical purity were >99 %. Radiochemical purity was evaluated also in human albumin for 7 days at 37 °C. Biodistribution studies have shown complete retention of injected radioactivity at the administration site up to 72 h.     

Simultaneous determination of mixtures of nitrophenols using multivariate curve resolution-alternating least squares

A simple procedure for the quantitative determination of mixtures of nitrophenols pollutants in environmental and biological samples based on continuous spectrophotometric acid–base titrations and multivariate curve resolution has been proposed. The procedure simultaneously takes into account the spectroscopic and acid–base properties of the nitrophenols, which leads to a higher selectivity. The quantitative determination of analyte in the presence of unknown and uncalibrated interferences is a general benefit of the method. Moreover, only one single synthetic standard containing of the analyte of interest is enough to perform the analysis. Because of the rank-deficiency phenomena, the pure spectra and concentration profiles of the species of interest can only be recovered through matrix augmentation. Even in the presence of the rank deficiencies, in most cases accurate quantitation with relative errors in prediction lower than 5 % was obtained. The percent recoveries obtained (92–108 %) were satisfactory.     

Rank analysis and simultaneous determination of acetylsalicylic acid,paracetamol, and caffeine in pharmaceuticals using second-order data and multivariate curve resolution-alternating least squares (MCR-ALS)

Mixtures of acetylsalicylic acid (ASA), paracetamol (PAR), and caffeine (CAF) have been successfully analyzed by constrained multivariate curve resolution-alternating least squares (MCR-ALS). The MCR-ALS methodology adequately exploits the second-order advantage which enables quantitation of analyte in the presence of unknown and uncalibrated interferences. The procedure simultaneously takes into account the spectroscopic and pH-dependent properties of the compounds, which leads to a higher selectivity. Specially, for CAF determination fully protonated or deprotonated forms of CAF are not dominant in the pH range of data acquisition but spectral changes with pH were recorded and used for accurate determination of CAF. Furthermore, quantitative determination of an analyte in a complex mixture is performed using a synthetic solution as standard containing only the analyte of interest. Even in the presence of the rank deficiencies, in most cases accurate quantitation with relative errors in prediction lower than 5 % was obtained. The procedure was successfully applied to the analysis of real samples (pharmaceuticals) using synthetic external standards. Percent relative errors of 4.03, 3.26, and 5.85 were obtained for ASA, PAR, and CAF, respectively, in A.C.A tablets and 4.49 and 2.75 for PAR and CAF, respectively in Novafen capsules.     

Synthesis of Some 3-Substituted 1,2-Dihydroindoles

The reaction of 4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6-methyl carboxylate 2 with hydrazine hydrate in methanol gave 4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6-carbonylhydrazine 3. Furthermore, the reaction of 3 with carbon disulfide and then hydrazine hydrate afforded 3-[6-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-4-oxo-1,3-thiazin-2-yl] hydrazone-1,3-dihydroindol-2-one 5. the latest reacted with DMAD to give {6-hydroxy-3-[4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6yl]-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-7-ylidene}methoxycarbonylmethylene 6.     

β-cyclodextrin-bonded silica particles as novel sorbent for stir bar sorptive extraction of phenolic compounds

A stir bar coated with β-cyclodextrin-bonded-silica (CDS) as novel sorbent has been developed and used to analyze seven phenolic compounds in aqueous samples, followed by thermal desorption and gas chromatography-mass spectrometric detection. Significant parameters affecting sorption process such as the time and temperature of sorption and desorption, ionic strength, pH and stirring rate have been optimized and discussed. The coating has a high thermal stability up to 300°C and long application lifetime (80 times). The porous structure of CDS coating provides high surface area and allows high extraction efficiency. Under the selected conditions, linearity range of 0.1-400 μg/L, limit of quantifications of 0.08-3.3 μg/L and method detection limits of 0.02-1.00 μg/L have been obtained. A satisfactory repeatability (RSD ≤ 6.5, n = 7) with good linearity (0.9975 ≤ r(2) ≤ 0.9996) of results illustrated a good performance of the present method. The recovery of different natural water samples was higher than 81.5%.     

A unique example of a co-crystal of [Ag(atr)2][Cr(dipic)2] (dipic = dipicolinate; atr = 3-amino-1H-1,2,4-triazole) and dinuclear [Cr(H2O)(dipic)(μ-OH)]2, with different coordination environment of Cr(III) ions

Treatment of a neutral aqueous solution of dipicolinic acid (dipicH₂), 3-amino-1H-1,2,4-triazole (atr) and CrCl₃·6H₂O in the presence of AgNO₃ (in molar ratio 1:1:1:3) under hydrothermal condition led to the formation of a co-crystal of {[Ag(atr)₂][Cr(dipic)₂]}₂·[Cr(H₂O)(dipic)(μ-OH)]₂·4H₂O (1). Compound 1 was characterized by elemental analyses, IR and UV-Vis spectroscopy as well as X-ray diffraction studies. The structure consists of two [Ag(atr)₂]⁺ cations, two [Cr(dipic)₂]⁻ anions, one co-crystallized neutral dinuclear chromium(III) complex, [Cr(H₂O)(dipic)(μ-OH)]₂, and four co-crystallized water molecules. Silver(I) ion in [Ag(atr)₂]⁺ is coordinated by two monodentate 3-amino-1H-1,2,4-triazole ligands, bound via endocyclic nitrogen atoms, in a linear fashion. Chromium(III) ion is octahedrally coordinated by two O,N,O-tridentate dipicolinate ligands in anionic complex. Each chromium(III) ion in neutral dinuclear complex, [Cr(H₂O)(dipic)(μ-OH)]₂, is octahedrally coordinated by one O,N,O-tridentate dipicolinate ligand, one water molecule and two bridging μ-OH ions in cis position. Thermal methods (TGA/DTA) confirm the number of co-crystallized water molecules in 1.     

Efficient regeneration of aldehydes from their corresponding 1,3-oxathiolanes in the absence of solvent

A mild and efficient method for the oxidative deprotection of 1,3-oxathiolanes with Fe（NO₃）₃·9H₂O and Cu（NO₃）₂·3H₂O in the absence of solvent is reported.     

Electrochemistry of Levo‐Thyroxin on Edge‐Plane Pyrolytic Graphite Electrode: Application to Sensitive Analytical Determinations

The electrochemical response of sodium levo‐thyroxin (T₄) at the surface of an edge plane pyrolytic graphite (EPPG) electrode is investigated using cyclic voltammetric technique in the presence of 0.1 M HCl as supporting electrolyte. T₄ underwent totally irreversible oxidation at this system and a well‐defined peak at 821 mV was obtained. Compared to the signals obtained in the optimized conditions at bare glassy carbon and carbon paste electrodes, the oxidation current of T₄ at an EPPG electrode was greatly enhanced. The electrochemical process of T₄ was explored and the experimental conditions were optimized. The oxidation peak current represented a linear dependence on T₄ concentration from 0.01 to 10 µM. The detection limit of 3 nM (S/N=3) was obtained for 250 s accumulation at 0.3 V. Determination of T₄ in a synthetic serum sample demonstrated that this sensor has good selectivity and high sensitivity.     

Dependence of the optical properties of UHV deposited silver thin films on the deposition parameters and their relation to the nanostructure of the films

Silver films were deposited on glass substrates under different deposition conditions, i.e. different film thicknesses, deposition rates and deposition angles. Their optical properties were measured by spectrophotometry in the spectral range of 185–3300 nm. The Kramers–Kronig method was used to analyze the reflectivity curves of the silver films to obtain their optical constants. The influence of substrate temperature on the microstructure of thin metallic films, the structure zone model (SZM), is well established, whereas there has been some previous work on the influence of film thickness and morphology, deposition rate and deposition angle on the microstructure and morphology of thin films. An effective medium approximation (EMA) analysis was used to establish the relationship between the atomic force microscopy results, SZM predictions and EMA results, and hence the optical properties of silver thin films. The predictions of the Drude free-electron theory are compared with experimental results for dielectric functions of Ag films produced under different deposition conditions. The real part of the dielectric constant increases with film thickness and decreases with increasing deposition rate and with increasing incidence angle, whereas the imaginary part of the dielectric constant decreases with increasing film thickness and deposition rate and with decreasing incidence angle over the whole energy range measured, including the interaband and interband regions.