Chiral counterion strategy in Cu-catalyzed asymmetric allylic oxidation of linear alkenes

Application of a chiral counter-ion strategy in the Kharasch-Sosnovsky reaction is reported. Copper(I) phosphates obtained from axially chiral, BINOL-derived phosphoric acids were investigated as catalysts in the enantioselective allylic oxidation of acyclic alkenes. Good yields and high regioselectivity towards branched allylic ester have been achieved. The chiral phosphates investigated exhibited modest enantioselectivities

Kinetic resolution of chiral racemic secondary allylboronates and their application in the synthesis of homoallylic amines [Abstract]

Kinetic resolution of chiral racemic secondary allylboronates and their application in the synthesis of homoallylic amines [Abstract

Dehydration of amides to nitriles under conditions of a catalytic appel reaction

A highly expedient protocol for a catalytic Appel-type dehydration of amides to nitriles has been developed that employs oxalyl chloride and triethylamine along with triphenylphosphine oxide as a catalyst. The reactions are usually complete in less than 10 min with only a 1 mol % catalyst loading. The reaction scope includes aromatic, heteroaromatic, and aliphatic amides, including derivatives of α-hydroxy and α-amino acids

Hydrazine-free solution-deposited CuIn(S,Se)2 solar cells by spray deposition of metal chalcogenides

Solution processing of semiconductors, such as CuInSe2 and its alloys (CIGS), can significantly reduce the manufacturing costs of thin film solar cells. Despite the recent success of solution deposition approaches for CIGS, toxic reagents such as hydrazine are usually involved, which introduce health and safety concerns. Here, we present a simple and safer methodology for the preparation of high-quality CuIn(S, Se)2 absorbers from metal sulfide solutions in a diamine/dithiol mixture. The solutions are sprayed in air, using a chromatography atomizer, followed by a postdeposition selenization step. Two different selenization methods are explored resulting in power conversion efficiencies of up to 8%

Kinetic resolution of secondary allylboronates and their application in the synthesis of homoallylic amines

Highly enantioenriched, chromatographically stable secondary allylboronates derived from 1,1,2,2‐tetraethyl‐1,2‐ethanediol were obtained by kinetic resolution of their racemic mixtures. The resolved reagents were applied in stereoselective synthesis of homoallylic amines with an internal double bond employing unprotected imines formed in situ from aldehydes and ammonia. The reactions proceeded with an excellent transfer of chirality

One-pot synthesis of (R)-convolutamydine A involving in situ chiral organocatalyst formation

The application of a convenient one-pot synthetic strategy, utilizing an in situ formed organocatalyst, to the enantioselective synthesis of anti-leukaemia agent (R)-convolutamydine A has been demonstrated

An innovative approach for fabrication of Cu2ZnSnSe4 absorber layers using solutions of elemental metal powders

An innovative approach has been demonstrated for the deposition of Cu2ZnSnSe4 (CZTSe) absorber layers. Using a unique, safe solvent combination, moving away from hydrazine, elemental Cu, Zn, Sn and S/Se can be fully dissolved at ambient conditions, with the composition easily controlled. The preparation and the spray deposition of these solutions are performed in air, allowing a quick, easy and inexpensive process. Upon selenisation, large crystals are observed which are identified as the CZTSe kesterite phase using X-ray diffraction and Raman, the latter showing no distinctive signs of any binary or ternary secondary phases. Using this method, CZTSe absorber layers have been prepared for use in thin-film solar cells reaching efficiency of 3.2%. With further device optimisation, improved device performance will be achieved

Hydrazine-free metal chalcogenide precursor solutions for sprayed CuIn(S,Se)2 thin film solar cells

CuIn(S,Se)2 (CIS) absorbers have been prepared by dissolving copper and indium sulphides in a hydrazine-free mixture of solvents, followed by spray deposition of the solution on molybdenum coated glass substrates. It was found that the choice of the solvent for dilution of the precursor solution can have an influence on the absorber quality and consequently, the device performance. The sprayed absorbers were implemented in solar cell devices, resulting in power conversion efficiencies (PCE) exceeding 7%

A comparison of different selenisation approaches for solution-processed Cu(In,Ga)(S,Se)2 solar cells

Hydrazine-free Cu(In,Ga)Se2 (CIGS) absorbers were fabricated using a low-cost atmospheric deposition method. The structural and electrical properties of thin film absorbers and the resulting solar cells processed using two different selenisation approaches were compared. A double selenisation process showed improved crystal structure compared to a single selenisation step, resulting in improved absorption throughout the spectrum and conversion efficiencies reaching 9.3%

Variation of Cu content of sprayed Cu(In,Ga)(S,Se)2 solar cells based on a Thiol-Amine solvent mixture

Cu(In,Ga)(S,Se)2 (CIGS) thin films were formed by a low cost solution-based approach using metal sulfide precursors. The stoichiometry of the absorber layer is tailored in order to improve film morphology and electrical properties. Cuy ln0.7Ga0.3Se2 films were prepared with a varied Cu content (0.8>y>1.1) and were completed in solar cell devices. The compositional, structural and electrical properties of the devices were investigated. Increased Cu content improves lateral crystallization, but results in the formation of Cu-rich secondary phases in-between CIGS grain boundaries. Characterization of the completed devices shows that Cu content has an important effect on the device electrical properties and the dominant recombination mechanisms