Medium effects on the initial and the transition states upon the solvolysis of trans‐dichlorobis(N‐methyl‐ethylenediamine)cobalt(III) complex in water‐mixed solvents

The kinetics of solvolysis of trans‐dichlorobis(N‐methylethylenediamine)cobalt(III) complex have been investigated in aqua‐organic solvent media (0–60% (v/v) cosolvent) at 25 ≤ t°C ≤ 60, using n‐propanol and tert‐butyl alcohol as cosolvents. The first‐order rate constant increased nonlinearly with the reciprocal of the dielectric constant D_s^?1, and x_org, reflecting the individuality of the cosolvents and thereby suggesting that the relative stabilities of the transition state and initial state were governed by the preferential solvation effect. The thermodynamic parameters (ΔH^≠ and ΔS^≠) were sensitive to the structural changes in the bulk solvent phase. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 495–499, 2002     

Chelation of somebisazophenyl-β-diketone derivatives with lanthanide metal ions

Summary The chelation behaviour ofbisazo--diketone compounds with La, Ce, Nd, Sm, Gd, Er, and Lu ions was investigated. Composition and stability constants of the chelates have been determined by conductometric and potentiometric techniques. Electronic absorption, IR, and¹H NMR spectra as well as molar conductance and elemental and thermal analyses were used to characterize the complexes.

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Komplexierung einiger Lanthaniden mitBisazophenyl--diketon-Derivaten

Zusammenfassung Das Komplexierungsverhalten einigerBisazophenyl--diketone mit La, Ce, Nd, Sm, Gd, Er und Lu wurde untersucht. Zusammensetzung und Stabilitätskonstanten der Chelate wurden mit konduktometrischen und potentiometrischen Methoden bestimmt. Zur Charakterisierung der Komplexe wurden UV/Vis-, IR- und¹H-NMR-Spektroskopie sowie molare Leitfähigkeit, Elementaranalyse und thermische Analyse herangezogen.

     

Two-dimensional q-differential transformation and its application

The one-dimensional q-differential transformation was introduced in [8] for solving the ordinary q-differential equations. Here, we present the definition and operation of the two-dimensional q-differential transform. A distinctive feature of the q-differential transform is its ability to solve linear and nonlinear partial q-differential equations.     

Novel Cr (III), Fe (III) and Ru (III) Vanillin Based Metallo‐Pharmaceuticals for Cancer and Inflammation Treatment: Experimental and Theoretical Studies

In this study, three novel complexes comprising trivalent Cr (III), Fe (III) and Ru (III) with imine ligand derived from 2‐amino‐3‐hydroxypyridine and o‐vanillin (H₂L) have been synthesized and characterized via wide range of spectroscopic and analytical tools such as ¹H NMR and ¹³C NMR, infrared (IR) and UV–Vis spectrophotometry, conductivity and magnetic measurements. The obtained results along with DFT data confirmed a 1:1 (metal: ligand) stoichiometry with non‐planner geometries for the three complexes. The binding action and the docking study of the prepared metal‐complexes to calf thymus DNA was also studied by absorption spectra and viscosity technique, which revealed that the three complexes interact strongly with DNA through intercalative binding mode. Significantly, these metal‐imine complexes showed strong and efficient anti‐inflammatory and antimicrobial activities against various gram‐positive (Microccus luteus), gram‐negative (Escherichia coli and Serratia marcescence) bacteria, and three strains of fungus. Moreover, all complexes exhibited more potent cytotoxicity effect on the outgrowth of different types of carcinoma cells, including human colon (HCT‐116 cell line), breast (MCF‐7 cell line), and hepatic cellular (HepG‐2), than the clinically‐proven Vinblastine standard.     

Study of non-isothermal crystallization kinetics of Ge20Se70Sn10 chalcogenide glass

Journal of Thermal Analysis and Calorimetry - The glass transition and non-isothermal crystallization behavior of Ge20Se70Sn10 glass prepared by the melt-quenching technique was investigated using...     

Recent progress on coumarin scaffold-based anti-microbial agents (Part III)

The biological, therapeutic, and medicinal properties of coumarins (chromen-2-ones), and its analogs have triggered enormous studies aimed toward growing synthetic routes to these heterocyclic compounds. This review presents a systematic and comprehensive survey of the method of preparation, the chemical reactivity, and the anti-microbial properties associated with this system.     

Sequential Chemistry Toward Core–Shell Structured Metal Sulfides as Stable and Highly Efficient Visible-Light Photocatalysts

A universal sequential synthesis strategy in aqueous solution is presented for highly uniform core–shell structured photocatalysts, which consist of a metal sulfide light absorber core and a metal sulfide co-catalyst shell. We show that the sequential chemistry can drive the formation of unique core–shell structures controlled by the constant of solubility product of metal sulfides. A variety of metal sulfide core–shell structures have been demonstrated, including CdS@CoS_x, CdS@MnS_x, CdS@NiS_x, CdS@ZnS_x, CuS@CdS, and more complexed CdS@ZnS_x@CoS_x. The obtained strawberry-like CdS@CoS_x core–shell structures exhibit a high photocatalytic H₂ production activity of 3.92 mmol h⁻¹ and an impressive apparent quantum efficiency of 67.3 % at 420 nm, which is much better than that of pure CdS nanoballs (0.28 mmol h⁻¹), CdS/CoS_x composites (0.57 mmol h⁻¹), and 5 %wt Pt-loaded CdS photocatalysts (1.84 mmol h⁻¹).     

Omega chrome green BLL: A new analytical reagent

Summary Omega Chrome Green BLL was used as a metal indicator for the direct complexometric titration of copper, lead, thorium and for the back titration of aluminium using thorium as a back titrant. It was also used as a colorimetric reagent for the microdetermination of copper and vanadium. A large number of anions and cations do not interfere in such a determination even if they are present in 10 folds the amount of copper or vanadium. Interference due to ferric iron is simply eliminated by the addition of few crystals of ascorbic acid to reduce it to the ferrous state.     

Validated UPLC method for the determination of guaiphenesin,oxeladin citrate,diphenhydramine, and sodium benzoate in their quaternary mixture used in treatment of cough,in the presence of guaiphenesin-related substance (guaiacol)

Accurate, precise, and sensitive UPLC method was developed and validated for the simultaneous determination of a quaternary mixture containing guaiphenesin (GUP), oxeladin citrate (OXC), diphenhydramine (DPH), and sodium benzoate (SOB) in the presence of GUP-related substance, guaiacol (GUA). Chromatographic separation was achieved using NUCLEOSHELL^® column—C₁₈ (4.0?×?50.0 mm, 2.7 μm). Isocratic elution at a flow rate 1.0 mL/min was performed using a mobile phase consisting of acetonitrile:phosphate buffer pH 3.5?±?0.1 (25.0:75.0, v/v). The specificity of the developed method was investigated by analyzing of laboratory-prepared mixtures containing different ratios of the four drugs, in the presence of GUA as well as their combined pharmaceutical formulation. The obtained results were statistically compared with those obtained by the official or reported methods, showing no significant difference with respect to accuracy and precision at p?=?0.05.