A novel pH-sensitive method for the quantification of Ca ions by complexometric titration with NaHEDTA.

A simple and accurate complexometric titration has been developed by the reaction between Ca ions (pH 7) and NaHEDTA (pH 11) solutions. Formation of a Ca-EDTA complex and release of H ions in the system were traced by a decrease in the pH. At the equivalence point of the titration, a sharp increase in the pH was observed.

Exploring the simultaneous σ-hole/π-hole bonding characteristics of a Br⋯π interaction in an ebselen derivative experimental and theoretical electron-density analysis.

In this study, the nature and characteristics of a short Br⋯π interaction observed in an ebselen derivative, 2-(2-bromophenyl)benzo[][1,2]selenazol-3(2)-one, has been explored. The electronic nature of this Br⋯π interaction was investigated high-resolution X-ray diffraction and periodic density functional theory calculations using atoms-in-molecules (AIM) analysis. This study unravels the simultaneous presence of σ-hole and π-hole bonding characteristics in the same interaction.

An ebselen like catalyst with enhanced GPx activity via a selenol intermediate.

The reaction of KSeO(t)Bu with 2-iodo-arylbenzamides gave benzamide ring-substituted, quinine-derived isoselenazolones 1b–1d. The reaction of PhSH with ortho-methyl-substituted isoselenazolone 1b gave selenol 3b, which is oxidized by H2O2 to regenerate 1b. Isoselenazolone 1b shows a high rate (0.

Transition-metal-free synthesis of unsymmetrical diaryl chalcogenides from arenes and diaryl dichalcogenides.

A transition-metal-free synthetic method has been developed for the synthesis of unsymmetrical diaryl chalcogenides (S, Se, and Te) from diaryl dichalcogenides and arenes under oxidative conditions by using potassium persulfate at room temperature. Variously substituted arenes such as anisole, thioanisole, diphenyl ether, phenol, naphthol, di- and trimethoxy benzenes, xylene, mesitylene, N,N-dimethylaniline, bromine-substituted arenes, naphthalene, and diaryl dichalcogenides underwent carbon-chalcogen bond-forming reaction to give unsymmetrical diaryl chalcogenides in trifluoroacetic acid. To understand the mechanistic part of the reaction, a detailed in situ characterization of the intermediates has been carried out by (77)Se NMR spectroscopy by using diphenyl diselenide as the substrate.

Isoselenazolones as catalysts for the activation of bromine: bromolactonization of alkenoic acids and oxidation of alcohols.

Isoselenazolones were synthesized by a copper-catalyzed Se-N bond forming reaction between 2-halobenzamides and selenium powder. The catalytic activity of the various isoselenazolones was studied in the bromolactonization of pent-4-enoic acid. Isoselenazolone 9 was studied as a catalyst in several reactions: the bromolactonization of a series of alkenoic acids with bromine or N-bromosuccinimide (NBS) in the presence of potassium carbonate as base, the bromoesterification of a series of alkenes using NBS and a variety of carboxylic acids, and the oxidation of secondary alcohols to ketones using bromine as an oxidizing reagent.

KO(t)Bu mediated synthesis of phenanthridinones and dibenzoazepinones.

Synthesis of substituted phenanthridinones and dibenzoazepinones has been realized from 2-halo-benzamides in the presence of potassium tert-butoxide and a catalytic amount of 1,10-phenanthroline or AIBN. This new carbon-carbon bond forming reaction gives direct access to various biaryl lactams containing six- and seven-membered rings chemoselectively. Carbon-carbon coupling seems to proceed by the generation of a radical in the amide ring which leads to C-H arylation of aniline.

Multifunctional Ebselen drug functions through the activation of DNA damage response and alterations in nuclear proteins.

Several studies have demonstrated that Ebselen is an anti-inflammatory and anti-oxidative agent. Contrary to this, studies have also shown a high degree of cellular toxicity associated with Ebselen usage, the underlying mechanism of which remains less understood. In this study we have attempted to identify a possible molecular mechanism behind the above by investigating the effects of Ebselen on Saccharomyces cerevisiae.

Cu-catalyzed efficient synthetic methodology for ebselen and related Se-N heterocycles.

An efficient copper-catalyzed method for the synthesis of biologically important ebselen and related analogues containing a Se-N bond has been developed. This is the first report of a catalytic process of selenation and Se-N bond formation reaction. Copper-catalyzed reaction tolerates functional groups such as amides, hydroxyls, ethers, nitro, fluorides, and chlorides.