Search

A palladium‐catalyzed [4+4] cycloaddition of aryl‐substituted γ‐methylidene‐δ‐valerolactones (GMDVs) with divinylketones (DVKs) was developed, providing an approach to access various mono‐cyclic tetrahydro‐2H‐oxocines with diverse substituents in 41% to 95% yield with 81:19 to >20:1 dr. This reaction was facilitated by anchoring olefin (C=C), carbonyl (C=O), and arene (Ar) at the α‐position of carbonyls. [ABSTRACT FROM AUTHOR]

The photoconductive gain theory demonstrates that the photoconductive gain is related to the ratio of carrier lifetime to carrier transit time. Theoretically, to achieve higher gain, one can either prolong the carrier lifetime or select materials with high mobility to shorten the transit time. However, the former slows the response speed of the device, while the latter increases the dark current and degrades device sensitivity. To address this challenge, a horizontal p-n-p junction-based photoconductor is proposed in this work. This device utilizes the n-region as the charge transport channel, with the charge transport direction perpendicular to the p-n-p junction. This design offers two advantages: (i) the channel is depleted by the space charge layer generated by the p and n regions, enabling the device to maintain a low dark current. (ii) The photovoltage generated in the p-n junction upon light absorption can compress the space charge layer and expand the conductive path in the n-region, enabling the device to achieve high gain and responsivity without relying on long carrier lifetimes. By adopting this device structure design, a balance between responsivity, dark current, and response speed is achieved, offering a new approach to designing high-performance photodetectors based on both traditional materials and emerging nanomaterials. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The diterpene synthase AfAS was identified from Aspergillus fumigatiaffinis. Its amino acid sequence and—according to a structural model—active site architecture are highly similar to those of the fusicocca‐2,10(14)‐diene synthase PaFS, but AfAS produces a structurally much more complex diterpene with a novel 6–5–5–5 tetracyclic skeleton called asperfumene. The cyclisation mechanism of AfAS was elucidated through isotopic labelling experiments and DFT calculations. The reaction cascade proceeds in its initial steps through similar intermediates as for the PaFS cascade, but then diverges through an unusual vicinal deprotonation‐reprotonation process that triggers a skeletal rearrangement at the entrance to the steps leading to the unique asperfumene skeleton. The structural model revealed only one major difference between the active sites: The PaFS residue F65 is substituted by I65 in AfAS. Intriguingly, site‐directed mutagenesis experiments with both diterpene synthases revealed that position 65 serves as a bidirectional functional switch for the biosynthesis of tetracyclic asperfumene versus structurally less complex diterpenes. [ABSTRACT FROM AUTHOR]

Rapid and efficient synthesis of targeted deoxygenated glycosides is highly desired. Herein, we disclose a two‐step procedure for the synthesis of deoxysugars from partially protected pyranosides via site‐selective thiocarbonylation followed by tin‐free Barton–McCombie deoxygenation. The selectivity can be smoothly achieved through anhydrous FeCl3 as the catalyst assisted by low‐priced benzoyltrifluoroacetonate (Hbtfa) ligand in the presence of K2CO3 as base. Further deoxygenation can be carried out using greener silicon reagent, avoiding highly toxic organotin reagents in traditional procedures. Conspicuous features of this method include mild conditions, easy operation, high selectivity and non or low toxic reagents, making it a more attractive strategy. [ABSTRACT FROM AUTHOR]

This work describes a flexible and stretchable battery pack configuration that exhibits highly stable performance under large deformation up to 100% biaxial stretching. Using stress-enduring printable inks and serpentine interconnects, the new screen-printing route offers an attractive solution for converting rigid battery units into a flexible, stretchable energy storage device. Coin-cell lithium ion batteries are thus assembled onto the island regions of a screen-printed, buckling-enabled, polymer-reinforced interconnect "island-bridge" array. Most of the strain on the new energy-storage device is thus accommodated by the stress-enduring serpentine structures, and the array is further reinforced by mechanically strong "backbone" layers. Battery pack arrays are assembled and tested under different deformation levels, demonstrating a highly stable performance (