Mechanochromic Delayed Fluorescence Switching in Propeller-Shaped Carbazole–Isophthalonitrile Luminogens with Stimuli-Responsive Intramolecular Charge-Transfer Excited States

Herein, the universal design of high-efficiency stimuli-responsive luminous materials endowed with mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) functions is reported. The origin of the unique stimuli-triggered TADF switching for a series of carbazole–isophthalonitrile-based donor–acceptor (D–A) luminogens is demonstrated based on systematic photophysical and X-ray analysis, coupled with theoretical calculations. It was revealed that a tiny alteration of the intramolecular D–A twisting in the excited-state structures governed by the solid morphologies is responsible for this dynamic TADF switching behavior. This concept is applicable to the fabrication of bicolor emissive organic light-emitting diodes using a single TADF emitter.     

Optimizing Charge Switching in Membrane Lytic Peptides for Endosomal Release of Biomacromolecules

Endocytic pathways are practical routes for the intracellular delivery of biomacromolecules. Along with this, effective strategies for endosomal cargo release into the cytosol are desired to achieve successful delivery. Focusing on compositional differences between the cell and endosomal membranes and the pH decrease within endosomes, we designed the lipid-sensitive and pH-responsive endosome-lytic peptide HAad. This peptide contains aminoadipic acid (Aad) residues, which serve as a safety catch for preferential permeabilization of endosomal membranes over cell membranes, and His-to-Ala substitutions enhance the endosomolytic activity. The ability of HAad to destabilize endosomal membranes was supported by model studies using large unilamellar vesicles (LUVs) and by increased intracellular delivery of biomacromolecules (including antibodies) into live cells. Cerebral ventricle injection of Cre recombinase with HAad led to Cre/loxP recombination in a mouse model, thus demonstrating potential applicability of HAad in vivo.     

One-Pot Synthesis of Chiral N-Arylamines by Combining Biocatalytic Aminations with Buchwald–Hartwig N-Arylation

The combination of biocatalysis and chemo-catalysis increasingly offers chemists access to more diverse chemical architectures. Here, we describe the combination of a toolbox of chiral-amine-producing biocatalysts with a Buchwald–Hartwig cross-coupling reaction, affording a variety of α-chiral aniline derivatives. The use of a surfactant allowed reactions to be performed sequentially in the same flask, preventing the palladium catalyst from being inhibited by the high concentrations of ammonia, salts, or buffers present in the aqueous media in most cases. The methodology was further extended by combining with a dual-enzyme biocatalytic hydrogen-borrowing cascade in one pot to allow for the conversion of a racemic alcohol to a chiral aniline.     

Synthesis of Polymers Containing Potassium Acyltrifluoroborates (KATs) and Post-polymerization Ligation and Conjugation

We report the synthesis of monomers for atom-transfer radical polymerization (ATRP) and a reversible addition-fragmentation chain transfer (RAFT) agent bearing trifluoroborate iminiums (TIMs), which are quantitatively converted into potassium acyltrifluoroborates (KATs) after polymerization. The resulting KAT-containing polymers are suitable for rapid amide-forming ligations for both post-polymerization modification and polymer conjugation. The polymer conjugation occurs rapidly, even under dilute (micromolar) aqueous conditions at ambient temperatures, thereby enabling the synthesis of a variety of linear and star-shaped block copolymers. In addition, we applied post-polymerization modification to the covalent linking of a photocaged cyclic antibiotic (gramicidin S) to the side chains of the KAT-containing copolymer. Cellular assays revealed that the polymer–antibiotic conjugate is biocompatible and provides efficient light-controlled release of the antibiotic on demand.     

Four-Component Borocarbonylation of Vinylarenes Enabled by Cooperative Cu/Pd Catalysis: Access to β-Boryl Ketones and β-Boryl Vinyl Esters

We report here a general four-component synthetic procedure for the preparation of β-boryl ketones and β-boryl vinyl esters. Joint catalyzed by palladium and copper catalysts, borocarbonylative reaction between vinylarenes, aryl halides/triflates, B₂Pin₂, and carbon monoxide proceed successfully. A variety of synthetically useful β-boryl ketones were synthesized in good to high yields by using aryl iodides as the substrates. It is noteworthy that when aryl triflates were applied as the starting materials, β-boryl vinyl esters were synthesized in a similar manner and with broad functional group tolerance. A rational mechanism for this reaction was also proposed.     

Acceptor-Doping Accelerated Charge Separation in Cu2O Photocathode for Photoelectrochemical Water Splitting: Theoretical and Experimental Studies

Cu₂O is a typical photoelectrocatalyst for sustainable hydrogen production, while the fast charge recombination hinders its further development. Herein, Ni²⁺ cations have been doped into a Cu₂O lattice (named as Ni-Cu₂O) by a simple hydrothermal method and act as electron traps. Theoretical results predict that the Ni dopants produce an acceptor impurity level and lower the energy barrier of hydrogen evolution. Photoelectrochemical (PEC) measurements demonstrate that Ni-Cu₂O exhibits a photocurrent density of 0.83 mA cm⁻², which is 1.34 times higher than that of Cu₂O. And the photostability has been enhanced by 7.81 times. Moreover, characterizations confirm the enhanced light-harvesting, facilitated charge separation and transfer, prolonged charge lifetime, and increased carrier concentration of Ni-Cu₂O. This work provides deep insight into how acceptor-doping modifies the electronic structure and optimizes the PEC process.