Differences in the Low-Energy Collision-Activated Dissociation of Car☐ylate Anions from Structurally Similar Prostaglandins: E2, F2α, D2 and DHKF2α

Some intriguing discoveries were made concerning the collision-activated dissociation behavior of the derivatized car☐ylate anions of PGE₂ and PGF_2α. The car☐ylate anion [M-PFB]⁻ formed from electron-capture negative chemical ionization of the pentafluorobenzyl ester-trimethylsilyl derivative of PGF_2α showed little fragmentation under typical collision gas pressures and energies (<2.0 mtorr N₂ and <20 eV). In contrast, the daughter spectra of the car☐ylate anion of the methoxime-pentafluorobenzyl ester-trimethylsilyl derivative of PGE₂ produced many intense fragments under the same conditions.     

Infrared and raman spectra,vibrational assignments,normal coordinate analysis,and ab initio calculations of methyltrifluoromethyldisulfide and bis(trifluoromethyl)disulfide

The infrared and Raman (3500-35 cm^–1) spectra of gaseous and solid methyltrifluoromethyldisulfide, CF₃SSCH₃, and bis(trifluoromethyl)disulfide, CF₃SSCF₃, have been recorded. Additionally, the Raman spectra of the neat liquids have been obtained and qualitative depolarization values have been measured. These vibrational data have been interpreted, for both molecules, on the basis that the C-S-S-C dihedral angle is approximately 90°. Vibrational assignments are given for both molecules and are supported by normal coordinate calculations utilizing ab initio Hartree-Fock gradient calculations with the 3-21G^* basis set to obtain the frequencies for the normal modes and potential energy distributions. The CH₃ and CF₃ torsional modes have been observed at 140 and 48 cm^–1, respectively, for CF₃SSCH₃, from which periodic barriers of 485 cm^–1 (1.39 kcal mol^–1) and 853 cm^–1 (2.44 kcal mol^–1), respectively, have been calculated. Complete equilibrium geometries have been determined for both molecules by ab initio calculations employing both 3–21G and 6–31G basis sets. The structural parameters for bis(trifluoromethyl)disulfide are compared to those suggested from electron diffraction studies. The results are compared to corresponding quantities obtained for some similar molecules.Taken in part from the thesis of M. M. Bergana which will be submitted to the Department of Chemistry in partial fulfillment of the Ph.D. degree.     

Extraction of actinium with di (2-ethylhexyl) phosphoric acid from hydrochloric and nitric acid solutions

The extraction of actinium with HDEHP from Cl^– and NO ₃ ^– systems has been investigated. It was found that extraction of actinium from HCl solutions is much better than from HNO₃ solutions. Stability constants of the actinium complexes Ac(X^–)²⁺, X^–=Cl^– or NO ₃ ^– , were determined. Our results show that actinium formed less stable complexes with Cl^– than with NO ₃ ^– ligands.     

Water in melts: Raman spectral investigation of the molten Ca(NO3)2·4H2O−KNO3 system

The Raman spectra of molten mixtures of Ca(NO₃)₂\4H₂O–KNO₃ have been examined, covering the concentration range of 0–70 mole% KNO₃. The frequencies in the spectra of the mixtures have been found to change slightly with concentration. Striking variations in the band shapes have been observed in the regions corresponding to the O–H stretching mode (2850–3850 cm^–1) and the v₄-NO ₃ ^– mode (700–750 cm^–). The results are discussed in terms of perturbed quasi-lattice structure for the melt, in which there could be a displacement of water molecules in the first coordination sphere around Ca²⁺ by the NO ₃ ^– ion.     

Anti-Inflammatory Effects of Mitrephora sirikitiae Leaf Extract and Isolated Lignans in RAW 264.7 Cells

Mitrephora sirikitiae Weeras., Chalermglin & R.M.K. Saunders has been reported as a rich source of lignans that contribute to biological activities and health benefits. However, cellular anti-inflammatory effects of M. sirikitiae leaves and their lignan compounds have not been fully elucidated. Therefore, this study aimed to investigate the anti-inflammatory activities of methanol extract of M. sirikitiae leaves and their lignan constituents on lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 mouse macrophage cells. Treatment of RAW 264.7 cells with the methanol extract of M. sirikitiae leaves and its isolated lignans, including (−)-phylligenin (2) and 3′,4-O-dimethylcedrusin (6) significantly decreased LPS-induced prostaglandin E₂ (PGE₂) and nitric oxide (NO) productions. These inhibitory effects of the extract and isolated lignans on LPS-induced upregulation of PGE₂ and NO productions were derived from the suppression of cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) production, respectively. In addition, treatment with 2-(3,4-dimethoxyphenyl)-6-(3,5-dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane (3) and mitrephoran (5) was able to suppress LPS-induced tumor necrosis factor alpha (TNF-α) secretion and synthesis in RAW 264.7 cells. These results demonstrated that M. sirikitiae leaves and some isolated lignans exhibited potent anti-inflammatory activity through the inhibition of secretion and synthesis of PGE₂, NO, and TNF-α.     

Osmotic coefficients of dilute aqueous solutions of unsymmetrical cobalt-amine type salts at 0°C

The osmotic coefficients of dilute aqueous solutions of [Co(pn)₃]X₃ [pn=1,2-diaminopropane and X=Cl^–, Br^– and (NO₃)^–] and [Co(tn)₃]X₃ (tn=1,3-diaminopropane and X=Cl^– and Br^–) have been measured from 0.00 to 0.02 mol-kg^–1 at 0°C by the freezing point method. The results have been compared with those obtained from the numerical integration of the Poisson-Boltzmann equation.     

Thermodynamics of Aqueous Diethylenetriaminepentaacetic Acid (DTPA) Systems: Apparent and Partial Molar Heat Capacities and Volumes of Aqueous H2DTPA3−, DTPA5−, CuDTPA3−, and Cu2DTPA− from 10 to 55°C

Apparent molar heat capacities and volumes have been determined for aqueous solutions of the mixed electrolytes Na₅DTPA + NaOH, Na₃CuDTPA + NaOH, and NaCu₂DTPA + NaOH, and the single electrolyte Na₃H₂DTPA (DTPA=diethylenetriaminepentaacetic acid) at temperatures from 10 to 55°C. The experimental results have been analyzed in terms of Young's rule with the Guggenheim form of the extended Debye–Hückel equation and the Pitzer ion-interaction model. These calculations led to standard partial molar heat capacities and volumes for the species H₂DTPA^3–(aq), DTPA^5–(aq), CuDTPA^3–(aq), and Cu₂DTPA^–(aq) at each temperature. The partial molar properties at 0.1 m ionic strength were also calculated. The standard partial molar properties were extrapolated to elevated temperatures with the revised Helgeson–Kirkham–Flowers (HKF) model. Values for the partial molar heat capacities from the HKF model have been combined with the literature data to estimate the ionization constants of H₂DTPA^3–(aq) and the formation constant of the CuDTPA^3–(aq) copper complex at temperatures up to 300°C.     

Co-hydrolysis products of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions: Part 2 [1]

²⁹Si NMR peaks due to species with the double four-membered ring siloxane backbone composed of both Si(O^–)_4/2 and CH₃Si(O^–)_3/2 units, (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=1–3), formed by co-hydrolysis of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions in methanol have been assigned. It has been found that ²⁹Si NMR peaks due to Si(OSi)₃(O^–) units shift to lower frequencies by replacement of the adjacent Si(O^–)_4/2 units by CH₃Si(O^–)_3/2 units, in other words, with increasing m value in Si[OSi(O^–)₃]_{3 – m} [OSi(CH₃) (O^–)₂] _m (O^–) (m=0–2). Peaks from CH₃ Si(OSi)₃ units in the species have also appeared as separated due to the kind of neighbor structural units. On the basis of the assignments, positions of CH₃Si(O^–)_3/2 units in the cubic octameric siloxane framework of (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=2, 3), for both of which three isomers are present, have been estimated.     

A New Predictive Equation for the Surface Tensions of Aqueous Mixed Ionic Solutions Conforming to the Linear Isopiestic Relation

The linear isopiestic relation has been used, together with the fundamental Butler equations, to establish a new simple predictive equation for the surface tensions of the mixed ionic solutions. This newly proposed equation can provide the surface tensions of multicomponent solutions using only the data of the corresponding binary subsystems of equal water activity. No binary interaction parameters are required. The predictive capability of the equation has been tested by comparing with the experimental data of the surface tensions for the systems HCl–LiCl–H₂O, HCl–NaClO₄–H₂O, HCl–CaCl₂–H₂O, HCl–SrCl₂–H₂O, HCl–BaCl₂–H₂O, LiCl–NaCl–H₂O, LiCl–KCl–H₂O, NaCl–KCl–H₂O, KNO₃–NH₄NO₃–H₂O, and LiCl–NaCl–KCl–H₂O at 298.15 K; KNO₃–NH₄Cl–H₂O, KBr–Sr(NO₃)₂–H₂O, NaNO₃–Sr(NO₃)₂–H₂O, NaNO₃ –(NH₄)₂SO₄–H₂O, KNO₃–Sr(NO₃)₂– H₂O, NH₄Cl–Sr(NO₃)₂–H₂O, NH₄Cl– (NH₄)₂SO₄–H₂O, KBr–KCl–H₂O, KBr–KCl–NH₄Cl–H₂O, KBr–KNO₃– Sr(NO₃)₂–H₂O, KBr–NH₄Cl–Sr(NO₃)₂–H₂O, KNO₃–NH₄Cl–Sr(NO₃)₂–H₂O, and NH₄Cl–(NH₄)₂SO₄–NaNO₃–H₂O at 291.15 K; and KBr–NaBr–H₂O at temperatures from 283.15 to 308.15 K. The agreement is generally quite good.     

Trace determination of TeO42?, TeO32?, AsO2? and VO3? by differential pulse polarography and resolution of binary and ternary mixtures of selected oxyanions

Summary A differential pulse polarographic method has been applied to the determination of trace concentrations of TeO ₄ ^2– , TeO ₃ ^2– , AsO ₂ ^– and VO ₃ ^– . The dependence of the differential pulse peak on various parameters was studied and optimum conditions for the analytical determination of these oxyanions were found. Limits of detection and quantitation have been calculated for the differential pulse polarographic determination of the investigated oxyanions. The selectivity of this technique for the determination of binary (TeO ₄ ^2– -TeO ₃ ^2– , TeO ₄ ^2– -AsO ₂ ^– and TeO ₄ ^2– -VO ₃ ^– ) mixtures and a ternary (TeO ₄ ^2– -TeO ₃ ^2– -AsO ₂ ^– ) mixture has also been reported.

---

Spurenbestimmung von TeO ₄ ^2– , TeO ₃ ^2– , AsO ₂ ^– und VO ₃ ^– durch Differential-Puls-Polarographie und Trennung binÄrer sowie ternÄrer Gemische von ausgewÄhlten Oxyanionen

     

Electronic absorption spectra,ESR spectra,and structure of coordination polyhedrons of titanium(III) in molten and “instantly cooled” systems of sodium phosphates and halides

The structure of Ti(III) coordination polyhedrons in both individual NaPO₃ and 70 mole % NaPO₃-30 mole % Na_nX mixtures (X=PO₃ ^3–, P₂O₇ ^4–, F^–, Cl^–) in the molten and solid states has been investigated on the basis of data from electronic absorption and ESR spectra. The formation of tetragonally distorted Ti(III) coordination polyhedrons with D_4h symmetry coordinated only by (PO₃ ^–)_n chains with the following values of the spectroscopic parameters for the molten (and solid) states has been established in all the phosphate systems investigated: 10Dq=17,300 (18,000) cm^–1 (Ds=50 cm^–1, Dt=5600, g=1.959, g₁=1.930, =93. cm^–1). It has been shown that the greater is the extent of depolymerization of the phosphate chains in the melt, the stronger is the Ti(III) coordination polyhedron formed; the following relative series of the depolymerizing strength of the anions has accordingly been established: PO₄ ^3–2O₇ ^4–––.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 610–614, September–October, 1989.     

Negative ion formation in compounds relevant to SF6 decomposition in electrical discharges

Dissociative and nondissociative electron attachment in the electron impact energy range 0–14 eV are reported for SOF₂ SOF₄, SO₂F₂, SF₄, SO₂, and SiF₄ compounds which can be formed by electrical discharges in SF₆. The electron energy dependences of the mass-identified negative ions were determined in a time-of-flight mass spectrometer. The ions studied include F^– and SOF ₂ ^–* from SOF₂; SOF ₃ ^– and F^– from SOF₄; SO₂F ₂ ^–* , SO₂F^–, F ₂ ^– , and F^– from SO₂F₂; SF ₄ ^–* and F^– from SF₄; O^–, SO^–, and S^– from SO₂; and SiF ₃ ^– and F^– from SiF₄. Thermochemical data have been determined from the threshold energies of some of the fragment negative ions. Lifetimes of the anions SOF ₂ ^–* , SO₂F ₂ ^–* , and SF ₄ ^–* are also reported.     

Far-infrared spectrum,barrier to internal rotation,ro structure,and ab initio calculations for acetylacetylene

The far-infrared spectrum has been recorded from 50 to 360 cm^–1 at a resolution of 0.10 cm^–1 for acetyiacetylene (1-butyne-3-one], CH₃C(O)CCH. The fundamental methyl torsion has been observed at 117.94 cm^–1, from which a periodic barrier to internal rotation has been calculated to be 346 cm^–1 (989 cal mol^–1]. Infrared spectra (3500-50 cm^–1] of the gas and solid and the Raman spectra (3500-100 cm^–1) of the gas, liquid, and solid are reported. Utilizing previously reported rotational constants for three isotopic species,r _o structural parameters have been determined for the heavy-atom skeleton. The fundamental vibrational frequencies, barrier to internal rotation, and structural parameters that have been obtained experimentally are compared to those obtained from ab initio Hartree-Fock calculations employing 3-21G, 6-31G, and DZ basis sets and to the corresponding quantities for some similar molecules.     

Apparent molal volumes of aqueous solutions of bis-tetraalkylammonium salts at 25°C: Methylene-group contribution to the limiting molal volume

Densities of aqueous solutions of a series of polymethonium chloride and bromide salts (CH₃)₃–N–(CH₂)_n–N–(CH₃)₃X₂ have been measured at 25°C. Apparent molal volumes have been calculated, and methylene-group contributions to the limiting apparent molal volumes °_v have been estimated. Constant values of the methylene-group contribution of 16.5 and 17.0 cm³-mole^–1 were obtained for the bromide and chloride salts, respectively. These values are consistent with methylene-group contributions reported for other series of organic electrolytes.     

The synthesis and properties of zeolite CF-3

The novel zeolite CF-3, with a high ratio of SiO₂/Al₂O₃ and a characteristic X-ray powder diffraction pattern, has been synthesized hydrothermally from a TMEDA-Na₂O–SiO₂–Al₂O₃–H₂O system at 200°C. The molar composition of CF-3 is (0.4–0.6)Na₂O·(1.5–6.3)TMEDA·Al₂O₃·(80–400)SiO₂·(0–17)H₂O·CF-3 is similar to ZSM-39 and melanophlogite, which have a clathrate-type structure.     

Pressure-induced coordination changes in LiBO2

The coordination and structure changes in LiBO₂ have been studied at high pressure and temperature up to 5 GPa and 1500 °C using in-situ high-pressure differential thermal analysis, infrared absorption spectra and X-ray diffraction. The layer framework structure of α-LiBO₂ is found to be compressed easily along the direction of c-axis, resulting in the formation of tetra-coordinated BO₄ units. The phase transition boundaries between α- and γ-LiBO₂ as well as between amorphous LiBO₂ hydrate and γ-LiBO₂ have negative pressure–temperature slopes. The conditions for transformation from α- to γ-LiBO₂ are lower than that necessary to transform amorphous LiBO₂ hydrate to γ-LiBO₂. Moreover, the melting curve of LiBO₂ has also been determined and has a positive pressure–temperature slope. Upon quenching from high pressure, LiBO₂ may not contain ^[3]B–O–^[3]B rings but contain more fraction of ^[4]B units with increasing pressure.     

Pulse radiolysis studies on the reactions of 3-pyridinol with oxidizing radicals

Reaction rate constants for the reactions of 3-pyridinol with oxidizing radicals viz. OH, N₃, Br ₂ ^– , Cl ₂ ^– , SO ₄ ^– and O^– have been determined in aqueous solutions at different, pH's. Absorption spectra of the product transient species have been recorded in the 320–600 nm region. In the alkaline region (pH 13) the N₃ reaction product decays in two steps and O^– does not bring about one-electron oxidation. Similarly, at neutral pH, SO ₄ ^– does not cause selective one-electron oxidation of 3-pyridinol.     

Electrodeposition of Lu on W and Al electrodes: Electrochemical formation of Lu–Al alloys and oxoacidity reactions of Lu(III) in the eutectic LiCl–KCl

The electrodeposition of lutetium on inert electrodes and the formation of lutetium–aluminium alloys were investigated in the eutectic LiCl–KCl in the temperature range 673–823 K. On a tungsten electrode, the electroreduction of Lu(III) proceeds in a single step and electrocrystalization plays an important role. Experimental current–time transients are in good agreement with theoretical models based on either instantaneous or progressive nucleation with three dimensional growth of the nuclei, depending on the working temperature. The diffusion coefficient of Lu(III) was determined by chronopotentiometry by applying the Sand equation. The activation energy for diffusion was found to be 31.5 ± 1.3 kJ mol⁻¹. Al₃Lu and mixtures of Al₃Lu and Al₂Lu, characterized by XRD analysis and SEM, were obtained from the LiCl–KCl melt containing Lu(III) by potentiostatic electrolysis using an Al electrode. The activity of Lu and the standard Gibbs energies of formation for Al₃Lu were estimated from open-circuit chronopotentiometric measurements. The E–pO²⁻(potential–oxoacidity) diagram for Lu–O stable compounds in LiCl–KCl at 723 K has been constructed by combining theoretical and experimental data. In this way, the apparent standard potential for the Lu(III)/Lu system has been determined by potentiometry. Potentiometric titrations of Lu(III) solutions with oxide donors, using a yttria stabilized zirconia membrane electrode “YSZME” as a pO²⁻ indicator electrode, have shown the stability of LuOCl and Lu₂O₃ in the melt and their solubility products have been determined at 723 K.     

A method of calibration of the formic acid monomer concentration in the gas phase

Pyrolysis of t-butyl formate, (CH₃)₃C-O-CHO, has been carried out in a carrier gas stream of Ar or N₂ in a temperature range of 200–400°C. Between 200 and 300°C, the pyrolysis yielded an equimolar mixture of HCOOH and (CH₃)₂C=CH₂. The results have been used as a calibration method for determining the concentration of the gas-phase HCOOH monomer without interference from the formation of the formic acid dimer. Using this technique, the gas-phase infrared absorption cross-section of HCOOH at 1105 cm^–1 (peak to valley) for the resolution of 0.5 cm^–1 has been determined to be 6.76×10^–19 cm² molecule^–1.     

Complex compounds of tetracycline with WO 4 2− and MoO 4 2− ions. Investigation by pH-metric and conductometric methods

By using pH-metric and conductometric methods it has been found that tetracycline (H₃TC) forms with WO ₄ ^2– and MoO ₄ ^2– ions the following complex compounds: [WO₃HTC]^2–, [WO₃(H₂TC)₂]^2– and [MoO₃(H₂TC)₂]^2–. Stability constants log/gb ₁ ^k =7.86 and log ₁ ^k =7.80 for [WO₃HTC]^2– and [MoO₃HTC]^2–, respectively, have been calculated from pH-metric measurements.