Shi-Yuan Liu,Lin-Yan Xu,Chun-Yu Liu,Zhi-Gang Ren,David James Young,Jian-Ping Lang
An efficient catalytic system containing [RuCl 2 (η 6 -p-cymene)] 2 and one P,N ligand, N-diphenylphosphino-2-aminopyridine ( L1 ) was loaded in catalyzing the alkylation of ketones with primary alcohols for a diverse array of substrates. Other five P,N ligands based on pyridin-2-amine and pyrimidin-2-amine were also examined in this reaction to explore the influence of steric hindrance and electronic effects. Monitoring by 1 H NMR and ESI-MS reveals a stable cationic L1 -coordinated ruthenium hydride intermediate, identified as [Ru(η 6 -p-cymene)(κ 2 - L1 )H] + . Organic intermediates consistent with a three-step dehydrogenation , alkylation and hydrogenation pathway were also observed. The final step in this reaction, the ruthenium-catalysed transfer hydrogenation reduction of α,β-unsaturated ketone with benzyl alcohol was performed separately.
Jinsong Qi,Shixun Wang,Arsenii Portniagin,Stephen V. Kershaw,Andrey L. Rogach
Lead-free two-dimensional metal halide perovskites have recently emerged as promising light-emitting materials due to their improved stability and attractive optical properties. Herein, a facile room temperature wet milling method has been developed to make Dion–Jacobson (DJ) phase ODASnBr4perovskite microcrystals, whose crystallization was accomplished via the aid of introduced primary alcohols: ethanol, butanol, pentanol, and hexanol. Due to the strong intermolecular hydrogen bonding, the use of ethanol promoted the formation of non-doped ODASnBr4microcrystals, with an emission peaked at 599 nm and a high photoluminescence quantum yield (PL QY) of 81%. By introducing other primary alcohols with weaker intermolecular hydrogen bonding such as butanol, pentanol, and hexanol, [SnBr6]4−octahedral slabs of the DJ perovskite microcrystals experienced various degrees of expansion while forming O–H…Br hydrogen bonds. This resulted in the emission spectra of these alcohol-doped microcrystals to be adjusted in the range from 572 to 601 nm, while keeping the PL QY high, at around 89%. Our synthetic strategy provides a viable pathway towards strongly emitting lead-free DJ perovskite microcrystals with an improved stability.Keywords:Dion–Jacobson perovskites;tin bromide perovskites;photoluminescence;crystallization;primary alcohols
In this study, conventional saturation recrystallization process was found to produce a complex mixture instead of pure Dion-Jacobson (DJ)-phase ODASnBr4 perovskite single crystals (ODA denotes protonated 1,8-octanediamine), which originated from the strong hydrogen bonding in diammonium cations and the interaction with polar hydrogen bromide solution, resulting in the formation of impurities. Thus, additional primary alcohols, including ethanol, 1-propanol, 1-butanol, and 1-pentanol, were introduced to treat that mixture with an attempt to remove undesired byproducts, while also resulting in the molecular doping and enhanced crystallinity of DJ perovskites. The formation of O–H...Br hydrogen bonds between [SnBr6]4– octahedron slabs and alcohols promoted the lattice coordination of the perovskites and the removal of undesired surface-absorbed water and byproducts, thereby achieving ODASnBr4[alcohol] perovskite microcrystals with high photoluminescence quantum yield close to 90%. Their thermal stability and oxidation resistance were also significantly enhanced as a result of improved lattice crystallinity and surface capping by dopants. The strategy introduced here offers prospects for further development of lead-free DJ perovskite materials with strong emissions and reliable stabilities.
The alteration of surface microstructures and chemical composition in cuticle of papaya fruit in response to chilling stress were comparatively studied between cultivars of ‘Risheng’ and ‘Suihuang’ after harvest. Fruit surface was covered by fissured wax layers in both cultivars. The presence of granule crystalloids was cultivar dependent, with higher abundance in 'Risheng' and lower in 'Suihuang'. Various typical very-long-chain aliphatics i.e., fatty acids, aldehydes, n -alkanes, primary alcohols, and n -alkenes dominated waxes; and cutin monomers were prominently 9/10,16-dihydroxyhexadecanoic acid in papaya fruit cuticle. Chilling pitting symptom was accompanied by modification of granule crystalloids into flat appearance and decreased primary alcohols, fatty acids, and aldehydes in ‘Risheng’, but no evident changes in ‘Suihuang’. The response of cuticle to chilling injury in papaya fruit might be not directly related to the overall amount of waxes and cutin monomers, but more likely to the alteration of appearance morphologies and chemical composition in cuticle.
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