Pyridinyl-Carbazole Fragments Containing Host Materials for Efficient Green and Blue Phosphorescent OLEDs

Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m². The most efficient green PhOLED with 10 wt% of Ir(ppy)₃ {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m², which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.     

Effect of desiccant isotherm on the design parameters of desiccant wheel

A one dimensional mathematical model is developed to optimize the design parameters of desiccant wheel. The result shows that after some value of design parameters, change in moisture removal is negligible. The optimum isotherm shape should be R = 0.1. At this isotherm optimum value of wheel length, and channel pitch should be in the range of 0.2–0.25 and 0.003–0.004 m respectively.     

Chromatography-Based Determination of Anabolic Steroids in Biological Fluids: Future Prospects Using Electrochemistry and Miniaturized Microchip Device

Anabolic steroids form one of the important classes of doping agents and their consumption has been found to give benefits to the athletes. Inspite of the fact that they also produce adverse effects and damage several organs and systems, their consumption is continuously increasing in competitive games. The World Anti-Doping Agency and International Olympic Committee have banned the use of anabolic steroids and several other compounds. This article focuses an over view of various chromatographic techniques commonly used for detecting anabolic steroids and their metabolites during last 3 years in human biological fluids to establish the cases of doping. The possibility of electrochemistry- and microchip-based techniques have been considered as possible techniques for future to achieve simple and fast analysis at the site of competitive games as the first tool to detect the cases of doping.

     

Highly Concise and Stereoselective Total Synthesis of (5R,7S)‐Kurzilactone

A highly concise and stereoselective total synthesis of (5R,7S)‐kurzilactone ( 1 ) was performed by a convergent approach by means of a Jacobsen's hydrolytic kinetic resolution, a Horner? Wadsworth? Emmons reaction for the construction of the α,β‐unsaturated δ‐lactone ring system, and a highly diastereoselective Mukaiyama aldol reaction for the introduction of the formal anti‐1,3‐diol unit (Schemes 2 and 3).     

Determination of uranium in process stream solutions from uranium extraction plant employing energy dispersive X-ray fluorescence spectrometry

Energy dispersive X-Ray fluorescence (EDXRFS) method is developed and standardized for the determination of uranium on routine basis in various process stream solutions, covering a vide range of concentrations from 0.1 to 400?g?L^?1, from an Uranium Extraction Plant at Nuclear Fuel Complex. The method has been applied to aqueous stream samples. Except for dilution, no much sample preparation was involved in the analysis and accordingly the experimental parameters were optimized. The calibration curve in the range of 0.1?C10?g?L^?1 of U was drawn manually using synthetic standard solutions prepared from U₃O₈ powder and L?? (13.61?keV) line of uranium was used for the measurements. The results from EDXRFS method are compared with other methods and are found to be in good agreement. The EDXRFS measurements carried over a range of 0.1?C350?g?L^?1 of uranium have shown a RSD of ±1?C5%. Also, the limitations of reported methods in literature and the advantages of present method are highlighted in the paper.     

O,O-Diethyl dithiophosphoric acid mediated direct synthesis of thioamides from aldehydes and ketones

A general and convenient method for a one-pot conversion of aldehydes and ketones into thioamides has been developed. The protocol involves oximation of aldehydes and ketones followed by deoxygenative thioamidation of oximes with O,O-diethyl dithiophosphoric acid which acts as an acid as well a source of sulfur. The method is operationally simple, high yielding, and also applicable to the conversion of amides and nitriles into the corresponding thioamides.     

Organocatalyzed stereoselective construction of N-formylpiperidines via a Michael-aza-Henry-hemiaminalization reaction cascade

An efficient asymmetric synthesis of N-formylpiperidines via an organocatalytic Michael-aza-Henry-hemiaminalization reaction cascade of an aldehyde, a nitroalkene, and an N-arylideneformamide is reported. The reaction is triggered by diphenylprolinol trimethylsilyl ether and creates two C-C and one C-N bonds leading to the formation of highly enantio-enriched N-formylpiperidines with five contiguous chiral centers in a one-pot operation.     

Synthesis of the C38–C54 spiroketal segment of halichondrin B

Stereoselective synthesis of the C38–C54 segment of a marine metabolite halichondrin B comprising KLM and N rings with a C44 spiroketal including 10 chiral centers is described. The salient features of the synthesis are Carreira’s addition, Sharpless asymmetric dihydroxylation and double alkylation of TosMIC strategy and double vinyl coupling reactions.     

The direct thioesterification of aldehydes with disulfides via NHC-catalyzed carbonyl umpolung strategy

An efficient N-heterocyclic carbene (NHC)-catalyzed direct thioesterification of aldehydes and α,β-unsaturated aldehydes (enals) with diaryl disulfides is reported. The protocol involves carbonyl umpolung reactivity of aldehydes and enals in which the carbonyl carbon attacks nucleophilically on diaryl disulfides to afford thioesters and α,β-unsaturated thioesters, respectively. However, aliphatic aldehydes are not suitable substrates for this reaction. No by-product formation, complete atom-economy, shorter reaction time, ambient temperature, operational simplicity, and high yields are the salient features of the present procedure.     

Stereoselective total synthesis of (+)-(6R,2′S)-cryptocaryalactone and (−)-(6S,2′S)-epi cryptocaryalactone via asymmetric acetate aldol reaction

The total synthesis of (+)-(6R,2′S)-cryptocaryalactone and (?)-(6S,2′S)-epi cryptocaryalactone is reported based on asymmetric acetate aldol reaction. Still–Gennari reaction, Evans acetal intramolecular oxa-Michael reaction and lactonisation are the key steps in the target synthesis.