Elucidating the Mechanism of Freeze‐Thaw Driven Content Mixing between Protocells

Posted on 13 September 2023 by nBenedikt Peter, nPetra Schwillen

“We show how recurring environmental constraints on ancient earth, namely cycles of freezing and thawing, might have driven the dissemination of genetic material in populations of primitive protocells. In this work, confocal fluorescence microscopy at sub-zero temperatures was used to gain mechanistic insights into inter-protocellular communication based on cyclic freezing and melting of the aqueous environment. The cover design highlights the transient formation of membrane pores that enable content diffusion across protocell membranes…” This and more about the story behind the front cover can be found in the Research Article at 10.1002/syst.202300008.

Abstract

The front cover artwork is provided by the Schwille group from the Max Planck Institute of Biochemistry in Martinsried. The image shows the dissemination of genetic material in a population of primitive protocells during freeze-thaw induced periods of membrane permeability. Read the full text of the Research Article at 10.1002/syst.202300008.

Dcalycinumines A–E, alkaloids with cytotoxic activities of nasopharyngeal carcinoma cells from Daphniphyllum calycinum

Posted on 13 September 2023 by

Comprehensive Summary

Five novel Daphniphyllum alkaloids, named dcalycinumines A–E (1–4, 6), and eight previously described Daphniphyllum alkaloids (5, 7–13) were isolated from Daphniphyllum calycinum. Compound 1 is the first Daphniphyllum alkaloid possessing a highly rearranged 6/6/6/7/5/6 hexacyclic architecture with a unique 3-methyl-1-azabicyclo [4,4,0] decane ring system. Compound 2 represents a rare diamino Daphniphyllum alkaloid with an unprecedented 6/5/5/6/6/5 carbon skeleton featuring a unique 1-aza-6-azaspiro [4,5] decane unit, whereas 3 also represents a rare diamino Daphniphyllum alkaloid as a possible precursor of 2. Compound 4 is the second example of C-22-nor yuzurimine-type alkaloids. Their structures and absolute configurations were elucidated by HRESIMS, NMR spectroscopic analyses, ECD calculations, and single-crystal X-ray diffraction. Moreover, compound 1 showed remarkable antitumor activities, which could inhibit the proliferation, migration and invasion of nasopharyngeal carcinoma cells, and promoted nasopharyngeal carcinoma cells apoptosis.

Stereoselective Synthesis of Iminosugar‐C‐Glycosides through Addition of Organometallic Reagents to N‐tert‐Butanesulfinyl Glycosylamines: A Comprehensive Study

Posted on 13 September 2023 by

A comprehensive study of the preparation and reactivity of N-tert-butanesulfinyl glycosylamines with simple Grignard and organo lithium reagents is reported. As they readily react as latent imine equivalents with a variety of carbon nucleophiles in batch and continuous flow chemistry, these carbohydrate derivatives constitute very useful precursors for the diastereoselective synthesis of bioactive compounds such as iminosugar-C-glycosides.

Abstract

A comprehensive study of the preparation and reactivity of N-tert-butanesulfinyl glycosylamines with simple Grignard and organo lithium reagents in batch vs. continuous flow chemistry is reported. As they readily react as latent imine equivalents with a variety of carbon nucleophiles, these carbohydrate derivatives constitute very useful precursors for the diastereoselective synthesis of bioactive compounds such as iminosugar-C-glycosides. A hybrid protocol, involving the addition of benzylmagnesium chloride to a (S_R)-arabinofuranosylamine substrate in flow, at room temperature, combined with a cyclization protocol in batch is also described for the first time. Of note, this semi-continuous flow process shortens the synthesis of imino-C-glycoside scaffolds to a single workday.

Lewis Acid Catalysed Chemoselective Amination of Alcohols Using Heterocyclic Thiones: An Avenue to Thiotetrazole Derivatives

Posted on 13 September 2023 by nSudhamoyee Kataky, nPikumoni Boruah, nAshim J. Thakurn

Herein, the development of a Cu(OTf)₂ catalysed chemoselective amination of alcohols using heterocyclic thiones is described. Notably, the method is additive, ligand or inert atmosphere free and shows good tolerance towards variety of alcohols and thiotetrazole derivatives affording good to excellent yields of the product.

Abstract

Herein,a protocol for the chemoselective formation of C−N bond using Cu(OTf)₂ as catalyst has been described using heterocyclic thiones. The reaction occurs preferentially at the nitrogen centre over the sulphur atom leading to C−N bond formation. Water being the only by-product, the reaction is environmentally friendly. The reaction proceeds without any additive, ligand or inert atmosphere and shows good tolerance towards variety of alcohols and thiotetrazole derivatives. Our developed protocol could be scaled up to gram scale efficiently, which highlights the efficacy of this method and might offer potential application in synthetic industry.

Highly Durable PtNi Alloy on Sb‐Doped SnO2 for Oxygen Reduction Reaction with Strong Metal‐Support Interaction

Posted on 13 September 2023 by nLiwei Fang, nShengsen Wang, nYiqing Lu, nChengwei Deng, nLiping Sun, nYuanhui Chengn

PtNi/Sb_0.11SnO₂ with high durability was synthesized by adjusting the doping amount of antimony. The prepared PtNi/Sb_0.11SnO₂ retained excellent catalytic activity and hardly reduced half-wave potential in acidic conditions after 10,000 cycles, which displayed its high durability.

Abstract

Carbon-supported Pt is currently used as catalyst for oxygen reduction reaction (ORR) in fuel cells but is handicapped by carbon corrosion at high potential. Herein, a stable PtNi/SnO₂ interface structure has been designed and achieved by a two-step solvothermal method. The robust and conductive Sb-doped SnO₂ supports provide sufficient surfaces to confine PtNi alloy. Moreover, PtNi/Sb_0.11SnO₂ presents a more strongly coupled Pt-SnO₂ interface with lattice overlap of Pt (111) and SnO₂ (110), together with enhanced electron transfer from SnO₂ to Pt. Therefore, PtNi/Sb_0.11SnO₂ exhibits a high catalytic activity for ORR with a half-wave potential of 0.860 V versus reversible hydrogen electrode (RHE) and a mass activity of 166.2 mA mg_Pt ⁻¹@0.9 V in 0.1 M HClO₄ electrolyte. Importantly, accelerated degradation testing (ADT) further identify the inhibition of support corrosion and agglomeration of Pt-based active nanoparticles in PtNi/Sb_0.11SnO₂. This work highlights the significant importance of modulating metal-support interactions for improving the catalytic activity and durability of electrocatalysts.

Exploring the Divergent Reactivity of Vinyl Radicals Emanating from Alkynes and Thiols via Photoredox Catalysis

Posted on 13 September 2023 by nSourav Kumar, nBhahwal Ali Shahn

This review describes the behaviour of vinyl radicals produced through photoredox catalysis and how different reactivity patterns have been achieved by manipulating its chemistry. The focus has been on constructing various valuable scaffolds through 1,1-difunctionalization, 1,2-difunctionalization, and cyclization reactions.

Abstract

Organic chemistry has seen a surge in visible-light-driven transformations, which offer unique reaction pathways and access to new synthetic possibilities. We aim to provide a comprehensive understanding of state-of-the-art photo-mediated alkyne functionalization, with a focus on the reactive behavior of vinyl radicals. This review outlines our contributions to the field, including developing new methods for forming carbon-carbon and carbon-heteroatom bonds.

Improvements in the Electrochemical Performance of Sodium Manganese Oxides by Ti Doping for Aqueous Mg‐Ion Batteries

Posted on 13 September 2023 by

Sodium manganese oxides as positive electrode materials for aqueous magnesium-ion batteries have attracted extensive attention. However, the structural stability of sodium manganese oxides is poor, thus we proposed a production process of titanium-doped sodium manganese oxides and used it as positive electrode materials for aqueous magnesium-ion batteries to obtain good electrochemical performance.

Abstract

In recent times, the research on cathode materials for aqueous rechargeable magnesium ion battery has gained significant attention. The focus is on enhancing high-rate performance and cycle stability, which has become the primary research goal. Manganese oxide and its derived Na−Mn−O system have been considered as one of the most promising electrode materials due to its low cost, non-toxicity and stable spatial structure. This work uses hydrothermal method to prepare titanium gradient doped nano sodium manganese oxides, and uses freeze-drying technology to prepare magnesium ion battery cathode materials with high tap density. At the initial current density of 50 mA g⁻¹, the NMTO-5 material exhibits a high reversible capacity of 231.0 mAh g⁻¹, even at a current density of 1000 mA g⁻¹, there is still 122.1 mAh g⁻¹. It is worth noting that after 180 cycles of charging and discharging at a gradually increasing current density such as 50–1000 mA g⁻¹, it can still return to the original level after returning to 50 mA g⁻¹. Excellent electrochemical performance and capacity stability show that NMTO-5 material is a promising electrode material.

The Growing Field of Photoswitchable Macrocycles: A Promising Way to Tune Various Properties with Light

Posted on 13 September 2023 by nCorentin Ludwig, nJuan Xien

Photoswitchable macrocycles: Recent development of azobenzene, diarylethene, (Stiff-)stilbene or dihydroazulene-based photoswitchable macrocycles, for which conformation, dynamic, photo or thermal isomerization can be controlled by multiple photoswitching units, coordination-driven self-assembly, anion/cation binding or pH modulation, is reviewed, along with applications in encapsulation and release, in the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light.

Abstract

Thanks to supramolecular interactions of macrocyclic compounds with their guest ions or molecules, macrocycles have found wide applications in molecular and chiral recognition, separation, transportation, molecular machines, and so on. Photoswitchable macrocycles are especially appealing and attracting more and more interest because the embedded molecular photoswitch enables dynamic control of molecular shape, conformation, and different properties by light, a non-invasive, remote and highly tunable stimulus. With available photochromic compounds, various photoswitchable macrocycles have been developed. In this review paper, we describe the recently reported photoswitchable macrocyclic compounds, with a focus on the control of the macrocyclic structure, dynamic, photo or thermal isomerization, as well as their applications on encapsulation and release of ionic or aromatic species, on the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light.

Chiral and Luminescent Organic Radicals

Posted on 13 September 2023 by nMengqi Wang, nEngui Zhao, nZikai Hen

Chiral luminescent radicals: Based on the origin of chirality, we classified the currently reported chiral luminescence radicals into three categories, intrinsic chiral luminescent radicals, luminescent radicals with chiral substitutions, and field-regulation-induced chiral luminescent radicals. This brief review of their properties aims to provide basic guidelines for the development of these systems and to support further development of novel chiral luminescent radical systems.

Abstract

Chiral luminescent materials are a class of materials capable of emitting circularly polarized light (CPL). Radicals are unique open-shell compounds with exceptional photoelectromagnetic properties that can be exploited in constructing novel chiral luminescent materials. This Concept discussed three main catalogues for producing organic CPL radicals, intrinsic chiral luminescent radicals, luminescent radicals with chiral substitutions, and field-regulation-induced chiral luminescent radicals. The brief review of their properties aims at providing basic guidelines and supporting further development of novel chiral luminescent radical systems.

Structural design of π‐d conjugated TMxB3N3S6 (x = 2, 3) monolayer toward electrocatalytic ammonia synthesis

Posted on 13 September 2023 by

Single−atom catalysts (SACs) have attracted wide attentions to be acted as potential electrocatalysts for nitrogen reduction reaction (NRR). However, the coordination environment of the single transition metal (TM) atoms is essential to the catalytic activity for NRR. Herein, we proposed four types of 3-, 4-coordinated and π−d conjugated TMxB3N3S6 (x = 2, 3, TM = Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Tc, Ru, Hf, Ta, W, Re and Os) monolayers for SACs. Based on density functional theory (DFT) calculations, I-TM2B3N3S6 and III-TM3B3N3S6 are the reasonable 3-coordinated and 4-coordinated structures screening by structure stable optimizations, respectively. Next, the structural configurations, electronic properties and catalytic performances of 30 kinds of the 3-coordinated I-TM2B3N3S6 and 4-coordinated III-TM3B3N3S6 monolayers with different single transition metal atoms were systematically investigated. The results reveal that B3N3S6 ligand is an ideal support for TM atoms due to existence of strong TM−S bonds. The 3-coordinated I-V2B3N3S6 is the best SAC with the low limiting potential (UL) of −0.01 V, excellent stability (Ef = −0.32 eV, Udiss = 0.02 V) and remarkable selectivity characteristics. This work not only provides novel π−d conjugated SACs, but also gives theoretical insights into their catalytic activities and offers reference for experimental synthesis.