Highly selective electrochemical hydrogenation of alkynes: Rapid construction of mechanochromic materials

Electrochemical hydrogenation has emerged as an environmentally benign and operationally simple alternative to traditional catalytic reduction of organic compounds. Here, we have disclosed for the first time the electrochemical hydrogenation of alkynes to a library of synthetically important Z-alkenes under mild conditions with great selectivity and efficiency. The deuterium and control experiments of electrochemical hydrogenation suggest that the hydrogen source comes from the solvent, supporting electrolyte, and base. The scanning electron microscopy and x-ray diffraction experiments demonstrate that palladium nanoparticles generated in the electrochemical reaction act as a chemisorbed hydrogen carrier. Moreover, complete reduction of alkynes to saturated alkanes can be achieved through slightly modified conditions. Furthermore, a series of novel mechanofluorochromic materials have been efficiently constructed with this protocol that showed blue-shifted mechanochromism. This discovery represents the first example of cis-olefins-based organic mechanochromic materials

Revealing the Subsurface Basal <a> Dislocation Activity in Magnesium Through Lattice Rotation Analysis

A method was proposed in this study to reveal the subsurface basal dislocation activity in Mg-Y alloy and determine the corresponding Burgers vector. This is achieved by correlating the slip directions of dislocations to the lattice rotation represented by the {0001} pole figure. The identified basal slip system by this approach was verified by micro-Laue diffraction. This method can be applied as a complementary method to the conventional slip trace analysis to study the dislocation behavior of Mg alloys

Characteristics and controlling factors of the organic-rich shale in the Wujiaping Formation of the Hongxing area, eastern Sichuan Basin

Objective The organic-rich shale of the Upper Permian Wujiaping Formation in the Hongxing area of eastern Sichuan is an important replacement area for shale gas exploration in the Sichuan Basin, and the exploration breakthroughs have been made. But how to achieve large-scale storage increase and efficient development needs to be tackled. Methods This paper investigates the source and reservoir quality characteristics of the shale of the Wujiaping Formation in the Hongxing area of eastern Sichuan based on lithological, geochemical and gas-bearing test and analysis data and discusses the factors controlling the development of high-quality reservoirs. Results The results show that the shale of the Wujiaping Formation has a good organic matter type, dominated by type Ⅱ1 kerogen, with high TOC content, high carbonate content and high gas content. The shale TOC content generally ranges from 1% to 11%, with an average value of 6.89%; the lithology is mainly siliceous shale and mixed shale, followed by calcareous shale, and the overall brittle mineral content is high; the reservoir organic matter pores are developed and have good physical properties, and the porosity generally ranges from 2% to 5%, with an average value of 3.1%. Comprehensive analysis shows that the high-quality reservoir of the Wujiaping Formation is strictly controlled by the depositional environment. The reservoir pore type is dominated by organic pores. Conclusion Under the control of this depositional model, sea level rise and fall, volcanic activity and palaeoclimate have jointly controlled the inhomogeneity and high-quality shale reservior distribution

Scalable production of structurally colored composite films by shearing supramolecular composites of polymers and colloids

Abstract Structurally colored composite films, composed of orderly arranged colloids in polymeric matrix, are emerging flexible optical materials, but their production is bottlenecked by time-consuming procedures and limited material choices. Here, we present a mild approach to producing large-scale structurally colored composite films by shearing supramolecular composites composed of polymers and colloids with supramolecular interactions. Leveraging dynamic connection and dissociation of supramolecular interactions, shearing force stretches the polymer chains and drags colloids to migrate directionally within the polymeric matrix with reduced viscous resistance. We show that meter-scale structurally colored composite films with iridescence color can be produced within several minutes at room temperature. Significantly, the tunability and diversity of supramolecular interactions allow this shearing approach extendable to various commonly-used polymers. This study overcomes the traditional material limitations of manufacturing structurally colored composite films by shearing method and opens an avenue for mildly producing ordered composites with commonly-available materials via supramolecular strategies

Structure-Tunable Construction of Colloidal Photonic Composites via Kinetically Controlled Supramolecular Crosslinking

Colloidal photonic composites (CPCs) combine a unique array of colloidal particles (CPs) with a polymer matrix and exhibit intriguing optical and mechanical properties strongly depending on their structures. One-step construction of CPCs with tunable structures is crucial for enriching their properties and matching application requirements, which is highly desirable yet challenging. Here, we present a general strategy for CPC construction with tunable structures from short-range to long-range order by one-step kinetically controlling the supramolecular crosslinking between CPs and supramolecular oligomers. Importantly, the assembly process is monitored in situ and the key factors for structural regulation, i.e., the critical volume fraction of CPs and the structural transition from crystal growth to lattice compression, are disclosed, which play critical roles in obtaining CPCs with a wide range of controllable structures. The as-obtained CPCs exhibit structural colors with different angle dependencies, versatile mechanical strengths, and appealing mechanochromic and self-healing capabilities. This work provides insights into the one-step construction of structure-tunable photonic materials, opening up exciting avenues for novel solution-processable photonics. © 2022 American Chemical Society. All rights reserved.11Nsciescopu

Metathesis Strategy for the Immobilization of Copper(II) onto Carboxymethyl­cellulose/Fe₃O₄ Nanohybrid Supports: Efficient and Recoverable Magnetic Catalyst for the CuAAC Reaction

To overcome the inherent obstacles facing the traditional surface modification of Fe₃O₄ magnetic nanoparticles with appropriate capping agents to anchor the catalytically active complexes, a novel retrievable copper­(II) catalyst immobilized on carboxymethyl­cellulose/Fe₃O₄ nanoparticles (Cu^II–CMC–Fe₃O₄) magnetic hybrid materials was successfully prepared through three steps of sequential metathesis and one step of oxidation. First, ferrous carboxymethyl­cellulose (CMC–Fe^II) was prepared by ionic exchange of ferrous chloride and sodium carboxymethyl­cellulose (CMC–Na). Second, the resulting CMC–Fe^II was treated with NaOH solution to form the corresponding hybrid material Na–CMC–Fe­(OH)₂, which proceeded to be exposed to the air to afford the Na–CMC–Fe₃O₄. Finally, the as-prepared Na–CMC–Fe₃O₄ was immersed in copper sulfate solution to self-assembly-fabricate the Cu^II–CMC–Fe₃O₄ hybrid catalyst by ionic exchange of Cu­(II) with Na–CMC–Fe₃O₄. The morphology and structural feature of the catalyst were characterized by different microscopic and spectroscopic techniques such as FT-IR, ICP-AES, XRD, SEM, EDS, TEM, TGA, and DSC. The ensuring catalyst has been successfully applied in the CuAAC reaction of benzyl halides, sodium azide, and terminal alkynes to the synthesis of 1,2,3-triazoles. Furthermore, the Cu^II–CMC–Fe₃O₄ could be easily isolated and recovered by magnetic decantation and reused for five consecutive cycles without much loss in activity

Selective C(sp³)–S Bond Cleavage of Thioethers to Build Up Unsymmetrical Disulfides

The selective C­(sp3)–S bond cleavage of thioethers was first developed to prepare unsymmetrical disulfides by using electrophilic halogenation reagents. In this strategy, NBS (N-bromosuccinimide) achieves selective furfuryl C­(sp3)–S bond cleavage of furfuryl alkylthioethers at room temperature. Meanwhile, NFSI (N-fluorobenzenesulfonimide) enables selective methyl C­(sp3)–S bond cleavage of aryl and alkyl methylthioethers at an elevated temperature. Notably, the substrate scope investigation indicates that the order of selectivity of the C–S bond cleavage is furfuryl C­(sp3)–S > benzyl C­(sp3)–S > alkyl C­(sp3)–S > C­(sp2)–S bond. Moreover, this practical and operationally simple strategy also provides an important complementary way to access various unsymmetrical disulfides with excellent functional group tolerances and moderate to good yields

Stimuli-Sensitive Biodegradable and Amphiphilic Block Copolymer-Gemcitabine Conjugates Self-Assemble into a Nanoscale Vehicle for Cancer Therapy

The availability and the stability of current anticancer agents, particularly water-insoluble drugs, are still far from satisfactory. A widely used anticancer drug, gemcitabine (GEM), is so poorly stable in circulation that some polymeric drug-delivery systems have been under development for some time to improve its therapeutic index. Herein, we designed, prepared, and characterized a biodegradable amphiphilic block <i>N</i>-(2-hydroxypropyl) methacrylamide (HPMA) copolymer–GEM conjugate-based nanoscale and stimuli-sensitive drug-delivery vehicle. An enzyme-sensitive oligopeptide sequence glycylphenylalanylleucylglycine (GFLG) was introduced to the main chain with hydrophilic and hydrophobic blocks via the reversible addition–fragmentation chain transfer (RAFT) polymerization. Likewise, GEM was conjugated to the copolymer via the enzyme-sensitive peptide GFLG, producing a high molecular weight (MW) product (90 kDa) that can be degraded into smaller MW segments (<50 kDa), and ensuring potential rapid site-specific release and stability <i>in vivo</i>. The amphiphilic copolymer-GEM conjugate can self-assemble into compact nanoparticles. NIR fluorescent images demonstrated that the conjugate-based nanoparticles could accumulate and be retained within tumors, resulting in significant increased antitumor efficacy compared to free GEM. The conjugate was not toxic to organs of the mice as measured by body weight reductions and histological analysis. In summary, this biodegradable amphiphilic block HPMA copolymer-gemcitabine conjugate has the potential to be a stimuli-sensitive and nanoscale drug-delivery vehicle