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Reactions of two magnesium(I) compounds, [{(ArNacnac)Mg}2] (ArNacnac = [HC(MeCNAr)2]‐Ar = mesityl (Mes) or o‐xylyl (Xyl)), with CO in the presence of [Mo(CO)6] lead to the reductive hexamerization of CO, and formation of magnesium benzenehexolate complexes, [{(ArNacnac)Mg}6(C6O6)].
Organic dyes, emitting in the second near‐infrared (NIR‐II, 900‐1700 nm) window, with high molar extinction coefficient (MEC) and quantum yield (QY) in aqueous is essential for in vivo bioimaging and biosensing. In this work, we developed a dibodipy based J‐aggregated aggregation induced emission (AIE) molecule THPP to meet this aim. THPP exhibits a high MEC of dibodipy structure and has intensified absorption and emission in J‐aggregated state, which significantly enhanced the fluorescence intensity (~55 folds) and extends the maximal absorption/emission wavelengths to 970/1010 nm in NIR‐II region. Based on the bright THPP , imaging with high frame rate (34 frames per second) in a deep ‘valid penetration depth’ up to 6 mm can be achieved.
An amino‐supported solid palladium‐catalyzed oxidative domino reaction has been developed for the diastereoselective construction of alkyne‐substituted cyclopentenol compounds. This hetero­ge­neous catalyst exhibits high efficiency and excellent chemoselectivity, as well as good recyclability. The chemoselectivity of the domino reactions was readily controlled by switching the solvent and catalyst. Chiral syntheses and an oxidative carbocyclization‐borylation reaction have also been developed based on the heterogeneous Pd‐catalyzed domino strategy.
Ru(II) compounds are widely used in catalysis, photocatalysis and medical applications. They are usually obtained in reductive environment as molecular O 2 can oxidize Ru(II) to Ru(III) and Ru(IV). Here we report the design, identification and evolution of an air‐stable surface ‐[bipy‐Ru(II)(CO) 2 Cl 2 ] site that is covalently mounted onto a polyphenylene framework. Such Ru(II) site was obtained by reduction of ‐[bipy‐Ru(III)Cl 4 ] ‐ with simultaneous ligand exchange from Cl ‐ to CO. This structural evolution was witnessed by a combination of in situ X‐ray and infrared spectroscopy studies. The ‐[bipy‐Ru(II)(CO) 2 Cl 2 ] site enables oxidation of CO with a turnover frequency of 0.73 × 10 ‐2 s ‐1 at 462 K, while the Ru(III) site is complete.
A curved non‐alternant polycyclic aromatic hydrocarbon (PAH) containing fused heptagon and pentagon units is presented, as well as its conformational changes upon stepwise oxidation. Single‐crystal X‐ray analyses for neutral, cationic, dicationic, and a mixed valence species 1⋅(1.+)3 enabled the observed functional properties to be related to the molecular and supramolecular structures. Abstract. A curved sp2 carbon scaffold containing fused pentagon and heptagon units (1) was synthesized by Pd‐catalyzed [5+2] annulation from a 3,9‐diboraperylene precursor and shows two reversible oxidation processes at low redox potential, accompanied by a butterfly‐like motion. Stepwise oxidation produced radical cation 1.+ and dication 12+. In the crystal.
The performance of Li‐ion batteries (LIBs) is highly dependent on their interfacial chemistry, which is regulated by electrolytes. Conventional electrolyte typically contains polar solvents to dissociate Li salts. Herein we report a weakly‐solvating electrolyte (WSE) that consists of a pure non‐polar solvent, which leads to a peculiar solvation structure where ion pairs and aggregates prevail under a low salt concentration of 1.0 M. Importantly, WSE forms unique anion‐derived interphases on graphite electrodes that exhibit fast‐charging and long‐term cycling characteristics. First‐principles calculations unravel a general principle that the competitive coordination between anions and solvents to Li ions is the origin of different interfacia.
Transition‐metal nitrenoids are well‐established for their C−H amination chemistry but this work demonstrates that N‐acylnitrenoids can surprisingly undergo C(sp3)–H oxygenations instead, even in an enantioselective fashion. Abstract. This study demonstrates for the first time that easily accessible transition‐metal acylnitrenoids can be used for controlled direct C(sp3)‐H oxygenations.
The first organocatalytic C(sp2)−H allylation of racemic trisubstituted allenoates with Morita–Baylis–Hillman (MBH) carbonates was achieved, providing highly functionalized tetrasubstituted allenoates with adjacent axial chirality and tertiary carbon stereocenters in high yields with good to excellent diastereoselectivities and enantioselectivities. Abstract. Herein we describe the first organocatalytic asymmetric C(sp2)−H allylation of racemic trisubstituted allenoates with Morita–Baylis–Hillman (MBH) carbonates to access axially chiral tetrasubstituted allenoates.
O Globo (Brazil) 09/27/2020 19:17
Ainda não foi dessa vez que o Botafogo venceu e muito menos saiu da zona de rebaixamento do Brasileirão. Em um confronto direto, que poderia catapultar o alvinegro na tabela, adivinhem? Empate. O oitavo em onze rodadas. A igualdade da vez foi com o Atlético-GO, fora de casa, por 1 a 1. Os gols foram de Victor Luís e Hyuri. O próximo compromisso do Botafogo é contra o Bahia, quarta-feira, em jogo adiado da primeira rodada. O time que mais empata no Brasileirão fez um jogo instável, alternou controle de posse e lapsos na marcação, especialmente no segundo tempo. Até Matheus Babi, fundamental em jogos recentes, não esteve no melhor dos dias. O empate é ainda mais frustrante - neste caso, para ambos - porque as chances apareceram. O goleiro Jea.
Despite extensive efforts by many practitioners in the field, methods for the direct α‐C–H bond functionalization of unprotected alicyclic amines remain rare. A new advance in this area utilizes N‐lithiated alicyclic amines. These readily accessible intermediates are converted to transient imines through the action of a simple ketone oxidant, followed by alkylation with a β‐ketoacid under mild conditions to provide valuable β‐amino ketones with unprecedented ease. Regioselective α′‐alkylation is achieved for substrates with existing α‐substituents. The method is further applicable to the convenient one‐pot synthesis of polycyclic dihydroquinolones through the incorporation of a SNAr step.
CsSn0.6Ge0.4I3 nanocrystals have been synthesized for the first time by a B‐site co‐alloying strategy. The introduction of Ge effectively decreases the high density of intrinsic Sn defects, resulting in an extended excitonic lifetime and enhanced solar cell performance. The stability of the new nanocrystals also improves owing to the effective protection of Sn2+ against oxidation. Abstract. Colloidal lead‐free perovskite nanocrystals have recently received extensive attention because of their facile synthesis, the outstanding size‐tunable optoelectronic properties, and less or no toxicity in their commercial applications. Tin (Sn) has so far led to the most efficient lead‐free solar cells, yet showing highly unstable characteristics in ambie.

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