Selective C-N σ Bond Cleavage in Azetidinyl Amides under Transition Metal-Free Conditions

Functionalization of amide bond via the cleavage of a non-carbonyl, C-N σ bond remains under-investigated. In this work, a transition-metal-free single-electron transfer reaction has been developed for the C-N σ bond cleavage of N-acylazetidines using the electride derived from sodium dispersions and 15-crown-5. Of note, less strained cyclic amides and acyclic amides are stable under the reaction conditions, which features the excellent chemoselectivity of the reaction. This method is amenable to a range of unhindered and sterically encumbered azetidinyl amides

Contact Geometry and Pathway Determined Carriers Transport through Microscale Perovskite Crystals

Abstract With the miniaturization of crystals‐based photoelectric devices, electrode contact‐geometries may play a critical role in determining the device performance. However, investigation of the role of electrode contact geometries in situ faces great challenges due to the electrode contact geometry is typically unmodifiable. To this end, a kind of liquid metal is employed as an adaptive‐deformable electrode to study the carrier transport through perovskite microcrystals, in which the electrode contacts geometries/positions and thus the carrier‐pathways can be adjusted. Under light illumination, a spike feature of photocurrent is observed when carriers transport along the perovskite microcrystal surface upon an edge‐contact geometry, which is absent as the carrier mainly transport through crystal interior upon a top‐contact geometry. Switching, rectifying, and memristor functions are selectively realized just by modifying the contact geometry. The underlying mechanism for the observations is further elucidated. This study provides a platform for studying carrier transport through microscale crystals with adjustable contact geometry and supplies an approach for fabricating diverse functional devices by changing the electrode contact‐geometries

Plasmon-Assisted Trapping of Single Molecules in Nanogap

The manipulation of single molecules has attracted extensive attention because of their promising applications in chemical, biological, medical, and materials sciences. Optical trapping of single molecules at room temperature, a critical approach to manipulating the single molecule, still faces great challenges due to the Brownian motions of molecules, weak optical gradient forces of laser, and limited characterization approaches. Here, we put forward localized surface plasmon (LSP)-assisted trapping of single molecules by utilizing scanning tunneling microscope break junction (STM-BJ) techniques, which could provide adjustable plasmonic nanogap and characterize the formation of molecular junction due to plasmonic trapping. We find that the plasmon-assisted trapping of single molecules in the nanogap, revealed by the conductance measurement, strongly depends on the molecular length and the experimental environments, i.e., plasmon could obviously promote the trapping of longer alkane-based molecules but is almost incapable of acting on shorter molecules in solutions. In contrast, the plasmon-assisted trapping of molecules can be ignored when the molecules are self-assembled (SAM) on a substrate independent of the molecular length

A Practical and Chemoselective Ammonia-Free Birch Reduction

A novel protocol for a significantly improved, practical, and chemoselective ammonia-free Birch reduction mediated by bench-stable sodium dispersions and recoverable 15-crown-5 ether is reported. A broad range of aromatic and heteroaromatic compounds is reduced with excellent yields

Transition-Metal-Free, Selective Reductive Deuteration of Terminal Alkynes with Sodium Dispersions and EtOD‑<i>d</i>₁

A transition-metal-free single electron transfer reaction has been developed for the synthesis of [D₃]-alkenes from terminal alkynes using sodium dispersions as the electron donor and EtOD-<i>d</i>₁ as the deuterium source. Both reagents are cost-effective and bench-stable. This practical method exhibits remarkable terminal alkyne selectivity and exclusive alkene selectivity. Excellent deuterium incorporations and yields were achieved across a broad range of terminal alkynes without olefin isomerization. Of note, this reaction is highly solvent dependent. <i>n</i>-Hexane provides unique enhancement to this reductive deuteration process

Development of a Modified Bouveault–Blanc Reduction for the Selective Synthesis of α,α-Dideuterio Alcohols

A modified Bouveault–Blanc reduction has been developed for the synthesis of α,α-dideuterio alcohols from carboxylic acid esters. Sodium dispersions are used as the electron donor in this electron transfer reaction, and ethanol-<i>d</i>₁ is employed as the deuterium source. This reaction uses stable, cheap, and commercially available reagents, is operationally simple, and results in excellent deuterium incorporation across a broad range of aliphatic esters, which provides an attractive alternative to reactions mediated by expensive pyrophoric alkali metal deuterides