Molecular structure and spectroscopic characterization of tetrakis (2,5-diamino-1,3,4-thiadiazolium) decabromodibismuthate(III)

The title compound [C₂H₅N₄S]₄[Bi₂Br₁₀]; [HL]₄[Bi₂Br₁₀] (L=2,5-diamino-1,3,4-thiadiazole) was prepared and characterized by means of X-ray, and IR measurements. The structure was solved by the heavy-atom method, and least-squares refinement of structural parameters led to a conventionalR factor of 0.036 (R _w =0.032) for 2425 independent reflections. The crystal consists of a condensed [Bi₂Br₁₀]^4– anion and four HL⁺ cations. The anion has three bromine atoms involved in hydrogen bonds with N-bonded H atoms; the nonprotonated nitrogen atom of the cation is involved in hydrogen bonds too. The metal atoms have distorted octahedral geometry.     

A rapid and precise method for the determination of oxygen in certain gases: Modified brady method

The modified brady method is a rapid one, requiring only about one hour for the analysis, but requires large samples of gas, 5 to 20 liters. The precision of the method described here-in is ± 0.004 to ± 0.4 in the low range of oxygen-concentration (0.01 to 0. 10 part per million oxygen),± 0.01 to ± 0.07 in the medium range of oxygen-concentration (0.1 to l .0 part per million oxygen)and ± 0.0 to ± 0.2 in the upper range of oxygen-concentration (1 to 15 parts per million oxygen). The liest precision (winkler method) previously reported was ± 0.3 part per million oxygen. The range of the method is 0.01 to 15 parts per million oxygen. The minimum amount of oxygen detectible is 0.005 part per million.     

Mismatch limitations on metal-fibre polarizers

If a fibre polarizer is spliced into a single-mode fibre, the achievable extinction ratio of the polarizer is modified because of the coupling to higher-order modes at one end of the polarizer and coupling back into the fundamental mode at the other end.     

Hydrogenation of β-Keto Sulfones to β-Hydroxy Sulfones with Alkyl Aluminum Compounds: Structure of Intermediate Hydroalumination Products

β-Hydroxy sulfones are important in organic synthesis. The simplest method of β-hydroxy sulfones synthesis is the hydrogenation of β-keto sulfones. Herein, we report the reducing properties of alkyl aluminum compounds R₃Al (R = Et, i-Bu, n-Bu, t-Bu and n-Hex); i-Bu₂AlH; Et₂AlCl and EtAlCl₂ in the hydrogenation of β-keto sulfones. The compounds i-Bu₂AlH, i-Bu₃Al and Et₃Al are the at best reducing agents of β-keto sulfones to β-hydroxy sulfones. In reactions of β-keto sulfones with aluminum trialkyls, hydroalumination products with β-hydroxy sulfone ligands [R₂AlOC(C₆H₅)CH₂S(O)₂(p-R¹C₆H₄]_n [where n = 1,2; 2aa: R = i-Bu, R¹ = CH₃; 2ab: R = i-Bu, R¹ = Cl; 2ba: R = Et, R¹ = CH₃; 2bb: R = Et, R¹ = Cl] and {[Et₂AlOC(C₆H₅)CH₂S(O)₂(p-ClC₆H₄]∙Et₃Al}_n 3bb were obtained. These complexes in the solid state have a dimeric structure, while in solutions, they appear as equilibrium monomer–dimer mixtures. The hydrolysis of both the isolated 2aa, 2ab, 2ba, 2bb and 3bb and the postreaction mixtures quantitatively leads to pure racemic β-hydroxy sulfones. Hydroalumination reaction of β-keto sulfones with alkyl aluminum compounds and subsequent hydrolysis of the complexes is a simple and very efficient method of β-hydroxy sulfones synthesis.     

Natural Compounds in the Battle against Microorganisms—Linalool

The purpose of this article is to present recent studies on the antimicrobial properties of linalool, the mechanism of action on cells and detoxification processes. The current trend of employing compounds present in essential oils to support antibiotic therapy is becoming increasingly popular. Naturally occurring monoterpene constituents of essential oils are undergoing detailed studies to understand their detailed effects on the human body, both independently and in doses correlated with currently used pharmaceuticals. One such compound is linalool, which is commonly found in many herbs and is used to flavor black tea. This compound is an excellent fragrance additive for cosmetics, enhancing the preservative effect of the formulations used in them or acting as an anti-inflammatory on mild skin lesions. Previous studies have shown that it is extremely important due to its broad spectrum of biological activities, i.e., antioxidant, anti-inflammatory, anticancer, cardioprotective and antimicrobial. Among opportunistic hospital strains, it is most active against Gram-negative bacteria. The mechanism of action of linalool against microorganisms is still under intensive investigation. One of the key aspects of linalool research is biotransformation, through which its susceptibility to detoxification processes is determined.     

Recent advances in indoline synthesis

Indoline is an important structural motif present in several biologically active compounds from both natural and synthetic origins. The occurrence of this heterocyclic unity in these compounds is closely related to the biological activities they exhibit. This fact stimulated efforts that have been made worldwide to develop new synthetic approaches to prepare indolines. In this paper we reviewed critically the methods for indoline synthesis developed in the last years (from 2010 to 2018).