Surface defects of perovskite films are effectively passivated using oxalic acid, which has two C=O groups and can passivate the Pb²⁺ related defects. The oxalic acid passivated perovskite solar cell exhibits a champion PCE of 21.67 % from the reverse measurement and PCE of 21.54 % from the forward measurement.

Abstract

Solution processed perovskite films usually exhibit numerous defect states on the surfaces of the films. Here in this work, oxalic acid (H₂C₂O₄), which has two C=O groups, is selected and used to passivate the surface defects of the two-step deposited perovskite films via post-treatment. Strong interaction between H₂C₂O₄ molecule and the Pb²⁺ ions located on the surface of perovskite film has been confirmed via Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which can result in an effective suppress of the surface defects. Furthermore, time-resolved PL spectrum indicates that carrier lifetime is prolonged in the H₂C₂O₄ passivated perovskite film. After optimizing the H₂C₂O₄ concentration, the target perovskite solar cells can demonstrate superior power conversion efficiencies (21.67 % from reverse measurement and 21.54 % from forward measurement) and superior device-stability.

The introduction of iron ionic sites by metal exchange of defective homometallic nickel pyrazolate frameworks generates non-precious, Earth-abundant, first-row heterometallic Fe/Ni-pyrazolate frameworks. The Fe incorporation at the Ni nodes of the framework allows to control the hydrogen peroxide activation, minimizing its decomposition and O2 liberation, occurring at the homometallic Ni nodes. The generation of Fe-OH reactive oxygen species at the heterometallic Fe/Ni nodes is demonstrated by the higher activity in the proof-of-concept oxidation of 1-phenylethanol to acetophenone in an aqueous medium.

Hydrophobic α-peptide induces fibrillization of tau and these hetero-aggregates are toxic in cell culture. ITC experiments showed the interaction of the α-peptide with tau full-length (441),4R (244-369), and both hexapeptides ²⁷⁵VQIINK²⁸⁰ and ³⁰⁶VQIVYK³¹¹ through hydrophobic interactions. Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. The incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH), a cytoplasmic enzyme whose release is linked to membrane damage Altogether, the data suggest that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.

Abstract

Tau and α-synuclein are proteins involved in pathologies known as tauopathies and synucleinopathies, respectively. Moreover, evidence shows that there is a crosstalk between them as is seen in the brains of individuals with sporadic neurodegenerative disorders. Based on that, we present data showing that the hydrophobic α-peptide ⁷¹VTGVTAVAQKTV⁸² induces the aggregation of the full-length tau fragment in the absence of heparin assessed by ThT. Moreover, AFM images reveal the presence of straight filaments and amorphous aggregates of full-length tau in the presence of the α-peptide. Additionally, ITC experiments showed the interaction of the α-peptide with tau full-length (441 amino acids),4R (amino acids from 244 to 369), and both hexapeptides ²⁷⁵VQIINK²⁸⁰ and ³⁰⁶VQIVYK³¹¹ through hydrophobic interactions. The Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. Furthermore, the incubation of extracellular aggregates with N2a cells showed morphological differences in the cellular body and the nucleus suggesting cell death. Moreover,, the incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH). Altogether, we found that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.

Serhiy Mikolaevich Reformats'kiy (1867–1934) (Russian, Sergei Nikolaevich Reformatsky) was one of the founding fathers of organic chemistry in Ukraine. His eponymous reaction, between α-halozinc esters and aldehydes and ketones to give β-hyroxyesters, survived both the Grignard reaction and the modern crossed aldol addition, partly because of its success in synthesizing hindered compounds. His life and legacy are presented.

Abstract

Serhiy Mykolayovych Reformatskyi, [Ukrainian: Рeφopмaтcьκий, Cepгiй Mиκoлaйoвич; Russian: Sergei Nikolaevich Reformatskii, РeΦopмaтcκий, Cepгeй Hиκoлaeвич (1860-1934)] was a product of Zaitsev's laboratory in Kazan Imperial University in Russia and one of the founding fathers of organic chemistry in Ukraine. He discovered his eponymous reaction while a graduate student in Kazan under Zaitsev, studying the synthesis of homoallylic alcohols. He modified this reaction by replacing the olefinic π bond of an allyl halide with a carbonyl group. In the prototype reaction, he treated ethyl haloacetates with zinc and aldehydes or ketones. The reaction gave the corresponding β-hydroxyesters and remains an important synthetic method. Work on the reaction over the ensuing century and a quarter has led to the discovery of analogous reactions using a wide range of metals, and even permitting the use of water as a solvent.

In this work, we studied the reaction mechanisms for CO2 reduction reaction (CRR) on the iron-doped graphene and its coordinating sulfur (S) and nitrogen (N) variants, FeNnS4-n (n=1-4), using density functional theory calculations. Our results revealed that the electronic property and catalytic reactivity of the surfaces can be tuned by varying the N and S atoms ratio. The CRR activities of the mixed surfaces, FeN3S1, FeN2S2, and FeN1S3, were better than FeN4 and FeS4, where the absolute value of the limiting potential of the mixed surface decreased by 0.3 V. Considering the stability, we suggest FeN3S surface to be favorable for CRR. For the bare surfaces, we found a positive linear correlation between the magnetic moment and the charge of Fe metal. For these surfaces, the reduction of CO (*CO + (H++e−)→ *CHO) was important in deciding the limiting potential. We found that the adsorption energy of CO displayed a volcano relationship with the magnetic moment of the Fe atom. The study showed that the change of local coordinating structure around the Fe atom could modify the electronic and magnetic properties of the active Fe center and improve the CRR activity performance.

Inspired from dynamic living systems that operate under out-of-equilibrium conditions in biology, developing supramolecular hydrogels with self-regulating and autonomously dynamic properties to further advance adaptive hydrogels with life-like behavior is important. This review presents recent progress of bio-inspired supramolecular hydrogels out-of-equilibrium. The principle of out-of-equilibrium self-assembly for creating bio-inspired hydrogels is discussed. Various design strategies have been identified, such as chemical-driven reaction cycles with feedback control and physically oscillatory systems. These strategies can be coupled with hydrogels to achieve temporal and spatial control over structural and mechanical properties as well as programmable lifetime. These studies open up huge opportunities for potential applications, such as fluidic guidance, information storage, drug delivery, actuators and more. Finally, we address the challenges ahead of us in the coming years, and future possibilities and prospects are identified.

Three series of linear extended benzofuran derivatives associating cyanovinyl unit and electron withdrawing systems such as paracyanophenyl (series 1) or pentafluorophenyl (series 2) moeities or the electron donor 3,4-dimethoxyphenyl (series 3) moiety have been prepared. The donor character of the benzofuran part is carried out either without modifying the conjugation by adding the electron donor methoxy groups to the 5 and 6 positions of the benzofuran (compounds BF2 and BF3) or by increasing the extension of the conjugation with the naphthofuran unit (BF4), and by the insertion of a furan ring between the benzofuran and the cyanovinylene bond (BF5). While all compounds show very low emission in solution, microcrystalline powders of almost all compounds show strong emission under excitation at 350 - 400 nm with emission colors ranging from blue - green to red. It is shown that this variation of the emission colors is essentially due to the type of stacking of the molecules in the solids for series 1 and 2. For series 3, it is above all the extension of the conjugation of the compounds which causes the red shift.

The deoxygenation of parent and substituted oxiranes by λ3σ3-phosphorus reagents has been explored in detail, therefore unveiling mechanistic aspects as well as regio- and stereochemical consequences. Attack to a ring C atom is almost always preferred over one-step deoxygenation by direct P-to-O attack. In most cases a carbene transfer occurs as first step, leading to a phosphorane and a carbonyl unit that thereafter react in the usual Wittig fashion via the corresponding λ5σ5-1,2-oxaphosphetane intermediate. Betaines rarely constitute true minima after the first C-attack to oxiranes, at least in the gas-phase. Use of the heavier derivatives AsMe3 and SbMe3 as oxirane deoxygenating reagents was also mechanistically studied. The thermodynamic tendency of λ3σ3-phosphorus reagents to act as oxygen (O-attack) or carbene acceptors (C-attack) was theoretically studied by means of the thermodynamic oxygen-transfer potential (TOP) and the newly defined thermodynamic carbene-transfer potential (TCP) parameters, that were explored in a wider context together with many other acceptor centres.

A one-pot transformation of hydroxylated propargylic benzoate into chiral ketones featuring an O-heterocycle is realized via sequential gold catalysis and basic hydrolysis. The gold chemistry entails tandem 3,3-sigmatropic rearrangement and asymmetric cyclization of hydroxylated allenyl ester intermediates, which is achieved via asymmetric metal-ligand cooperation. The products were formed with good enantioselectivities despite the allenyl ester intermediate is racemic.

Abstract

By combining tandem asymmetric gold catalysis and subsequent stereoconvergent hydrolysis of enol ester in a one-pot process, hydroxylated propargylic esters are converted into chiral β-oxygenated ketones with mostly good enantiomeric ratios and in largely good to excellent yields. The product chiral center is formed via stereoselective cyclization of a hydroxylated allenyl ester intermediate, which is enabled by asymmetric gold-ligand cooperation.

Unlocking the potential of phosphino hydrazones: Harnessing the power of hydrazone condensation to synthesise phosphino hydrazone ligands from 3-(diphenylphosphino)propanal and commercially available aryl hydrazines and studying their palladium complexes for Cu-free Sonogashira cross-coupling reaction.

Abstract

Phosphino hydrazones represent a versatile class of nitrogen-containing phosphine ligands. Herein, we report a modular synthesis of phosphino hydrazone ligands by hydrazone condensation reaction of three different aryl hydrazines with 3-(diphenylphosphino)propanal (PCHO). Complexation reactions of these phosphino hydrazone ligands with palladium(II) and platinum(II) were investigated and the catalytic activity of the palladium(II) complexes was explored in a Cu-free Sonogashira cross-coupling reaction achieving yields up to 96 %. Additionally it was shown that the catalytically active species is homogeneous.