An appreciation of the chemical approach of V. V. Boldyrev to the study of the decomposition of solids

Professor Vladimir V. Boldyrev has made numerous important contributions to a wide range of chemical topics, not only limited to studies of the decompositions of solids. Of particular value has been his emphasis on exploring, in detail, the chemical steps participating in the thermal reactions of solids by carefully designed experiments that rely on more observational evidence than the run-of-the-mill collection of overall kinetic data. Some of these major contributions to both the theory and the uses of solid-state reactions are identified here and discussed in relation to his illuminating and fundamental mechanistic studies of the thermal decompositions of silver oxalate, ammonium perchlorate, potassium permanganate and the dehydration of copper sulfate pentahydrate.     

Vibrational spectral studies of L-citrullinium perchlorate

Infrared and Raman spectra of L-citrullinium perchlorate crystals have been recorded at room temperature. The vibrational assignments of the observed wavenumbers are proposed on the basis of group theoretical analysis. The presence of carbonyl group indicates that the molecule exists in the ionic form. The shifting of stretching and bending wavenumbers indicates the presence of extensive hydrogen bonding in the crystal. The anion fundamentals however continue to be degenerated. This suggests that its symmetry is not affected in the crystal.     

Kinetics of luminescence of CsI single crystals scavenged by Y3+

CsI single crystals were grown from the melt scavenged by Y³⁺ (YCl₃) addition in 6.7·10⁻⁴–6.7·10⁻³ mol·kg⁻¹ range. The addition of the scavenger amounts comparable with the total concentration of the oxygen‐containing admixtures in molten CsI results in complete destruction of the latter. Because of this, the intensity of the band with a maximum at 2.8 eV in radioluminescence spectra caused by the oxygen‐containing admixtures (anion vacancies) considerably decreases, and the fraction of the slow 2μs‐component corresponding to these admixtures becomes lower than 0.01 (0.007). The addition of larger quantities of YCl₃ leads to the appearance of a wide band with a maximum at 2.8 eV caused by cation vacancies, and the intensity of the slow 2μs‐component increases to 0.02. The maximum ratio of two faster components with the decay constants equal to 7 and 30 ns reaches 0.65:0.33 at Y³⁺ concentration in CsI melt equal to 6.7·10^‐3 mol·kg^‐1, the effective luminescence time of fastest components is ca 14 ns. The dependence of the ‘Fast/Total ratio’ on Y³⁺ concentration passes through its maximum (0.81) corresponding to the equivalence of Y³⁺ and O²⁻ concentrations in the growth CsI melt.     

Yttria‐based sol–gel coating for capillary microextraction online coupled to high‐performance liquid chromatography

This work about the development of yttria‐based polymeric coating using [bis(hydroxyethyl) amine] terminated polydimethylsiloxanes and yttrium trimethoxyethoxide inside the capillary. The coated capillary was utilized for online capillary microextraction and high‐performance liquid chromatography analysis. The prepared coating material was characterized using scanning electron microscopy, X‐ray photoelectron spectroscopy, energy dispersive X‐ray spectrometry, and thermogravimetric analysis. The coated capillary with polymer presented better extraction efficiency compared with the pure yttria‐based coated capillary with applicability in extreme pH environments (pH 0–pH 14). Excellent extraction towards polyaromatic hydrocarbons, aldehydes, ketones, alcohols, phenols, and amides was observed with limit of detection ranging from 0.18 to 7.35 ng/mL (S/N = 3) and reproducibility in between 0.6 and 6.8% (n = 3). Capillary‐to‐capillary extraction analysis has presented reproducibility between 4.1 and 9.9%. The analysis provided linear response for seven selected phenols in the range of 5–200 ng/mL with R² values between 0.9971 and 0.9998. The inter‐day, intra‐day, and capillary‐to‐capillary reproducibility for phenols was also <10%. Real sample analysis by spiking 5, 50, and 200 ng/mL of phenols in wastewater and pool‐water produced recovery between 84.7 and 94.3% and reproducibility within 7.6% (n = 3).     

Luminescence centers in thin films of yttrium oxide and yttrium-aluminum garnet activated with bismuth

Luminescence spectra and photoluminescence excitation spectra of Y₂O₃:Bi and Y₃Al₅O₁₂:Bi thin films were investigated. Luminescence was stimulated by the emission from two types of centers that were associated with the substitution of Bi³⁺ for Y³⁺ in sites of the crystal lattice of Y₂O₃ (Y₃Al₅O₁₂) with point symmetries C₂ and C_3i (D₂ and C_3i). The emission of Bi³⁺ in the site with point symmetry C_3i causes blue luminescence in both Y₂O₃:Bi and Y₃Al₅O₁₂:Bi films with maxima at 3.03 eV and 3.15 eV, respectively, that is related to the ³P₁-¹S₀ transition. The emission of Bi³⁺ in the site with point symmetry C₂ gives green luminescence in Y₂O₃:Bi with the maximum at 2.40 eV that is also related to the ³P₁-¹S₀ transition. The emission of Bi³⁺ in the site with point symmetry D₂ leads to ultraviolet luminescence in Y₃Al₅O₁₂:Bi with the maximum at 3.75 eV that corresponds to the ³P₁-¹S₀ transition. The red luminescence band with the maximum at 1.85 eV in Y₂O₃:Bi is due to the presence of structural defects. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 202–207, March–April, 2008.     

Raman spectra of crystalline iron perchlorate hexahydrate

Raman studies of crystalline iron perchlorate hexahydrate (Fe(ClO₄)₂·6H₂O) in the region of lattice and anion internal modes were carried out in the temperature range 80–385 K. The temperature‐dependent Raman results are consistent with those from previous works, showing that two phase transitions occur around 336 and 245 K. The transition at 336 K may be considered as an order–disorder transformation, while the one at 245 K is associated with the configurational disorder of the tetrahedron of the perchlorate ions. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman spectrum of decrespignyite [(Y,REE)4Cu(CO3)4Cl(OH)5·2H2O] and its relation with those of other halogenated carbonates including bastnasite,hydroxybastnasite, parisite and northupite

Raman spectroscopy complemented with infrared spectroscopy has been used to study the rare‐earth‐based mineral decrespignyite [(Y,REE)₄Cu(CO₃)₄Cl(OH)₅· 2H₂O] and the spectrum compared with the Raman spectra of a series of selected natural halogenated carbonates from different origins including bastnasite, parisite and northupite. The Raman spectrum of decrespignyite displays three bands at 1056, 1070 and 1088 cm⁻¹ attributed to the CO₃²⁻ symmetric stretching vibration. The observation of three symmetric stretching vibrations is very unusual. The position of the CO₃²⁻ symmetric stretching vibration varies with the mineral composition. The Raman spectrum of decrespignyite shows bands at 1391, 1414, 1489 and 1547 cm⁻¹, whereas the Raman spectra of bastnasite, parisite and northupite show a single band at 1433, 1420 and 1554 cm⁻¹, respectively, assigned to the ν₃ (CO₃)²⁻ antisymmetric stretching mode. The observation of additional Raman bands for the ν₃ modes for some halogenated carbonates is significant in that it shows distortion of the carbonate anion in the mineral structure. Four Raman bands are observed at 791, 815, 837 and 849 cm⁻¹, which are assigned to the (CO₃)²⁻ν₂ bending modes. Raman bands are observed for decrespignyite at 694, 718 and 746 cm⁻¹ and are assigned to the (CO₃)²⁻ν₄ bending modes. Raman bands are observed for the carbonate ν₄ in‐phase bending modes at 722 cm⁻¹ for bastnasite, 736 and 684 cm⁻¹ for parisite and 714 cm⁻¹ for northupite. Multiple bands are observed in the OH stretching region for decrespignyite, bastnasite and parisite, indicating the presence of water and OH units in the mineral structure. Copyright © 2011 John Wiley & Sons, Ltd.     

Copper(II) perchlorate complexes with antipyrine: synthesis,structure, cytotoxicity and DFT calculations

The synthesis, structure and properties of copper(II) perchlorate complexes with antipyrine (AP), [Cu(AP)₄(H₂O)](ClO₄)₂ and [Cu(AP)₅](ClO₄)₂, are described and compared with those of alternative compounds containing different AP ligands.