Reductive Doping Inhibits the Formation of Isomerization‐Derived Structural Defects in N‐doped Poly(benzodifurandione) (n‐PBDF)

2024-03-28T13:08:12+00:00March 28th, 2024|Categories: Publications|

Reductive doping effectively prevents the creation of defects caused by structural changes (isomerization) during the production of n-doped poly(benzodifurandione) (n-PBDF). This process involves several mechanisms, including hydride transfer, the integer charge transfer, or the formation of charge transfer complexes, to stop structural isomerization. Abstract Recently, solution-processable n-doped poly(benzodifurandione) (n-PBDF) has been made through in-situ oxidative polymerization and reductive doping, which exhibited exceptionally high electrical conductivities and optical transparency. The discovery of n-PBDF is considered a breakthrough in the field of organic semiconductors. In the initial report, the possibility of structural defect formation in n-PBDF was proposed, based on the observation of structural isomerization from (E)-2H,2′H-[3,3′-bibenzofuranylidene]-2,2′-dione (isoxindigo) to chromeno[4,3-c]chromene-5,11-dione (dibenzonaphthyrone) in the dimer model reactions. In this study, we present clear evidence that structural isomerization is inhibited during polymerization. We reveal that the dimer (BFD1) and the trimer (BFD2) can be reductively doped by several mechanisms, including hydride transfer, forming charge transfer complexes (CTC) or undergoing an integer charge transfer (ICT) with reactants available during polymerization. Once the hydride transfer adducts, the CTC, or the ICT product forms, structural isomerization can be effectively prevented even at elevated temperatures. Our findings provide a mechanistic understanding of why isomerization-derived structural defects are absent in n-PBDF backbone. It lays a solid foundation for the future development of n-PBDF as a benchmark polymer for organic electronics and beyond.

Published in: "Angewandte Chemie International Edition".

Chelating Additive Regulating Zn‐Ion Solvation Chemistry for Highly Efficient Aqueous Zinc‐metal Battery

2024-03-28T13:08:10+00:00March 28th, 2024|Categories: Publications|Tags: |

Aqueous zinc-metal batteries (AZMBs) usually suffered from poor reversibility and limited lifespan because of serious water induced side-reactions, hydrogen evolution reactions (HER) and rampant zinc (Zn) dendrite growth. Reducing the content of water molecules within Zn-ion solvation sheaths can effectively suppress those inherent defects of AZMBs. In this work, we originally discovered that the two carbonyl groups of N-Acetyl-ε-caprolactam (N-ac) chelating ligand can serve as dual solvation sites to coordinate with Zn2+, thereby minimizing water molecules within Zn-ion solvation sheaths, and greatly inhibit water-induced side-reactions and HER. Moreover, the N-ac chelating additive can form a unique physical barrier interface on Zn surface, preventing the harmful contacting with water. In addition, the preferential adsorption of N-ac on Zn (002) facets can promote highly reversible and dendrite-free Zn2+ deposition. As a result, Zn//Cu half-cell within N-ac added electrolyte delivered ultra-high 99.89% Coulombic efficiency during 8000 cycles. Zn//Zn symmetric cells also demonstrated unprecedented long life of more than 9800 hours (over one year). Aqueous Zn//ZnV6O16·8H2O (Zn//ZVO) full-cell preserved 78% capacity even after ultra-long 2000 cycles. A more practical pouch-cell was also obtained (90.2% capacity after 100 cycles). This method offers a promising strategy for accelerating the development of highly efficient AZMBs.

Published in: "Angewandte Chemie International Edition".

Towards More Sustainable Aqueous Zinc‐Ion Batteries

2024-03-26T13:08:50+00:00March 26th, 2024|Categories: Publications|Tags: |

Aqueous zinc-ion batteries (AZIBs) are considered as the promising candidates for large-scale energy storage because of their high safety, low cost and environmental benignity. The large-scale applications of AZIBs will inevitably result in a large amount of spent AZIBs, which not only induce the waste of resources, but also pose environmental risks. Therefore, sustainable AZIBs have to be considered to minimize the risk of environmental pollution and maximize the utilization of spent compounds. Herein, this minireview focus on the sustainability of AZIBs from material design and recycling techniques. The structure and degradation mechanism of AZIBs are discussed to guide the recycling design of the materials. Subsequently, the sustainability of component materials in AZIBs is further analysed to pre-evaluate their recycling behaviors and mentor the selection of more sustainable component materials, including active materials in cathodes, Zn anodes, and aqueous electrolytes, respectively. According to the features of component materials, corresponding green and economic approaches are further proposed to realize the recycling of active materials in cathodes, Zn anodes and electrolytes, respectively. These advanced technologies endow the recycling of component materials with high efficiency and a closed-loop control, ensuring that AZIBs will be the promising candidates of sustainable energy storage devices.

Published in: "Angewandte Chemie International Edition".

NIR‐II Absorption/Fluorescence of D–A π‐Conjugated Polymers Composed of Strong Electron Acceptors Based on Boron‐Fused Azobenzene Complexes

2024-03-26T13:08:48+00:00March 26th, 2024|Categories: Publications|Tags: |

Luminescence in the second near-infrared (NIR-II, 1,000–1,700 nm) window is beneficial especially for deep tissue imaging and optical sensors because of intrinsic high permeability through various media. Strong electron-acceptors with low-lying lowest unoccupied molecular orbital (LUMO) energy levels are a crucial unit for donor–acceptor (D–A) π-conjugated polymers (CPs) with the NIR-II emission property, however, limited kinds of molecular skeletons are still available. Herein, D–A CPs involving fluorinated boron-fused azobenzene complexes (BAz) with enhanced electron-accepting properties are reported. Combination of fluorination at the azobenzene ligand and trifluoromethylation at the boron can effectively lower the LUMO energy level down to −4.42 eV, which is much lower than those of conventional strong electron-acceptors. The synthesized series of CPs showed excellent absorption/fluorescence property in solution over a wide NIR range including NIR-II. Furthermore, owing to the inherent solid-state emissive property of the BAz skeleton, obvious NIR-II fluorescence from the film (up to λFL = 1213 nm) and the nanoparticle in water (λFL = 1036 nm, brightness = up to 29 cm–1 M–1) were observed, proposing that our materials are applicable for developing next-generation of NIR-II luminescent materials.

Published in: "Angewandte Chemie International Edition".

Induced Chirality in Canthaxanthin Aggregates Reveals Multiple Levels of Supramolecular Organization

2024-03-23T13:07:59+00:00March 23rd, 2024|Categories: Publications|

Carotenoids tend to form supramolecular aggregates via non-covalent interactions where the chirality of individual molecules is amplified to the macroscopic level. We show that this can also be achieved for non-chiral carotenoid monomers interacting with polysaccharides. The chirality induction in canthaxanthin (CAX), caused by heparin (HP) and hyaluronic acid (HA), was monitored by chiroptical spectroscopy. Electronic circular dichroism (ECD) and Raman optical activity (ROA) spectra indicated the presence of multiple carotenoid formations, such as H- and J-type aggregates. This is consistent with molecular dynamics (MD) and density functional theory (DFT) simulations of the supramolecular structures and their spectroscopic response.

Published in: "Angewandte Chemie International Edition".

Electro/Ni Dual‐Catalyzed Decarboxylative C(sp3)−C(sp2) Cross‐Coupling Reactions of Carboxylates and Aryl Bromide

2024-03-23T13:07:57+00:00March 23rd, 2024|Categories: Publications|

Paired redox-neutral electrolysis offers an attractive green platform for organic synthesis by avoiding sacrificial oxidants and reductants. Carboxylates are non-toxic, stable, inexpensive, and widely available, making them ideal nucleophiles for C−C cross-coupling reactions. Here, we report the electro/Ni dual-catalyzed redox-neutral decarboxylative C(sp3)−C(sp2) cross-coupling reactions of pristine carboxylates with aryl bromides. At a cathode, a NiII(Ar)(Br) intermediate is formed through the activation of Ar−Br bond by a NiI-bipyridine catalyst and subsequent reduction. At an anode, the carboxylates, including amino acid, benzyl carboxylic acid, and 2-phenoxy propionic acid, undergo oxidative decarboxylation to form carbon-based free radicals. The combination of NiII(Ar)(Br) intermediate and carbon radical results in the formation of C(sp3)−C(sp2) cross-coupling products. The adaptation of this electrosynthesis method to flow synthesis and valuable molecule synthesis was demonstrated. The reaction mechanism was systematically studied through electrochemical voltammetry and density functional theory (DFT) computational studies. The relationships between the electrochemical properties of carboxylates and the reaction selectivity were revealed. The electro/Ni dual-catalyzed cross-coupling reactions described herein expand the chemical space of paired electrochemical C(sp3)−C(sp2) cross-coupling and represent a promising method for the construction of the C(sp3)−C(sp2) bonds because of the ubiquitous carboxylate nucleophiles and the innate scalability and flexibility of electrochemical flow-synthesis technology.

Published in: "Angewandte Chemie International Edition".

Intermediate Color Emission via Nanographenes with Organic Fluorophores

2024-03-23T13:07:55+00:00March 23rd, 2024|Categories: Publications|Tags: |

Nanographenes (NGs) produced by top-down methods carry multiple functional groups. We utilized this aspect for the reproduction of purple light by adding red- and blue-light emitting fluorophores. Based on our results, NGs can be utilized as carriers of fluorophores capable of generating intermediate colors of light. Abstract Photoluminescence (PL) color can be tuned by mixing fluorophores emitting the three primary colors in an appropriate ratio. When color tuning is achieved on a single substrate, we can simplify device structures. We demonstrated that nanographenes (NGs), which are graphene fragments with a size of tens of nanometers, could be utilized as carriers of fluorophores. The addition of red- and blue-light-emitting fluorophores on the edge successfully reproduced the purple light. The relative PL intensities of the fluorophores could be regulated by the excitation wavelength, enabling multicolor emission between blue and red light. Owing to the triphenylamine units of the fluorophores, the NGs showed PL enhancement due to aggregation. This characteristic was valuable for the fabrication of solid polymer materials. Specifically, the functionalized NGs can be dispersed into polyvinylidene difluoride. The resultant polymer films emitted red, blue, and purple color. Our study demonstrated the potential applicability of NGs for fluorophore carriers capable of reproducing intermediate colors of light.

Published in: "Angewandte Chemie International Edition".

Correspondence to “Structure of Violet Phosphorus and Its Phosphorene Exfoliation”

2024-03-23T13:07:50+00:00March 23rd, 2024|Categories: Publications|Tags: |

In 1865 Johann Wilhelm Hittorf discovered violet phosphorus and it took until 1969 when Thurn and Krebs determined the structure of orthogonally arranged tubes with pentagonal cross-sections. Different to their claim, the structure determined by Zhang et al. in 2020 depicted in orange is identical to the 1969 structure shown in green and should not be referenced as a new polymorph. Abstract The structure described in the publication “Structure of Violet Phosphorus and Its Phosphorene Exfoliation” (Angew. Chem. Int. Ed. 2020, 59, 1074–1080) is identical to the structure by Thurn and Krebs determined already in 1969 and therefore by no means a new modification.

Published in: "Angewandte Chemie International Edition".

Modular Weaving DNAzyme in Skeleton of DNA Nanocages for Photoactivatable Catalytic Activity Regulation

2024-03-23T13:07:49+00:00March 23rd, 2024|Categories: Publications|

A general approach is established for spatiotemporal control of DNAzyme-based gene regulation activity through modular weaving active DNAzyme into skeleton of tetrahedral DNA nanocages (TDN). The direct encoding of DNAzyme in TDN not only improves biostability and delivery efficiency, but also allows spatiotemporal control of their catalytic activity. Abstract DNAzymes exhibit tremendous application potentials in the field of biosensing and gene regulation due to its unique catalytic function. However, spatiotemporally controlled regulation of DNAzyme activity remains a daunting challenge, which may cause nonspecific signal leakage or gene silencing of the catalytic systems. Here, we report a photochemical approach via modular weaving active DNAzyme into the skeleton of tetrahedral DNA nanocages (TDN) for light-triggered on-demand liberation of DNAzyme and thus conditional control of gene regulation activity. We demonstrate that the direct encoding of DNAzyme in TDN could improve the biostability of DNAzyme and ensure the delivery efficiency, comparing with the conventional surface anchoring strategy. Furthermore, the molecular weaving of the DNA nanostructures allows remote control of DNAzyme-mediated gene regulation with high spatiotemporal precision of light. In addition, we demonstrate that the approach is applicable for controlled regulation of the gene editing functions of other functional nucleic acids.

Published in: "Angewandte Chemie International Edition".

Investigating the Therapeutic Effects of Ferroptosis on Myocardial Ischemia‐Reperfusion Injury Using Dual‐Locking Mitochondrial Targeting Strategy

2024-03-22T13:08:36+00:00March 22nd, 2024|Categories: Publications|

Research of ferroptosis in myocardial ischemia/reperfusion injury (MIRI) using mitochondrial viscosity as a nexus holds great promise for MIRI therapeutics. However, high precision visualizing mitochondrial viscosity remains a formidable task owing to the debilitating electrostatic interaction caused by damaged mitochondrial membrane potential. Herein, we proposed a dual-locking mitochondrial targeting strategy that incorporates the idea of electrostatic forces and probe-protein molecular docking. Even in the damaged mitochondria, stable and precise visualization of mitochondrial viscosity in triggered and medicated MIRI was achieved owing to the sustained driving forces (pi-cation, pi-alkyl interactions etc.) between the developed probe CBS and mitochondrial membrane protein. Moreover, complemented by the western blot technology, we confirmed that ferrostatin-1 exerts its therapeutic effect on MIRI by improving the system xc−/GSH/GPX4 antioxidant system, confirming the therapeutic value of ferroptosis in MIRI. This work presents a new strategy for developing robust mitochondrial probes, thereby advancing the treatments for MIRI.

Published in: "Angewandte Chemie International Edition".

Discovery of Selective and Potent ATR Degrader for Exploration its Kinase‐Independent Functions in Acute Myeloid Leukemia Cells

2024-03-22T13:08:34+00:00March 22nd, 2024|Categories: Publications|

In the present work, a selective and potent ATR degrader was identified which was used as probe for explore the kinase-independent function of ATR. The results showed that ATR kinase inhibitor induced cell cycle arrest and inhibited the growth of AML cells. The ATR degrader was inclined to trigger immediate apoptosis in AML cells. A plausible explanation for this phenomenon is that ATR deletion induced nuclear envelope rupture, leading to genome instability, irreparable DNA damage. It causes to upregulate the level of p53 and subsequently triggers p53-mediated cell apoptosis. Abstract ATR has emerged as a promising target for anti-cancer drug development. Several potent ATR inhibitors are currently undergoing various stages of clinical trials, but none have yet received FDA approval due to unclear regulatory mechanisms. In this study, we discovered a potent and selective ATR degrader. Its kinase-independent regulatory functions in acute myeloid leukemia (AML) cells were elucidated using this proteolysis-targeting chimera (PROTAC) molecule as a probe. The ATR degrader, 8 i, exhibited significantly different cellular phenotypes compared to the ATR kinase inhibitor 1. Mechanistic studies revealed that ATR deletion led to breakdown in the nuclear envelope, causing genome instability and extensive DNA damage. This would increase the expression of p53 and triggered immediately p53-mediated apoptosis signaling pathway, which was earlier and more effective than ATR kinase inhibition. Based on these findings, the in vivo anti-proliferative effects of ATR degrader 8 i were assessed using xenograft models. The degrader significantly inhibited the growth of AML cells in vivo, unlike the ATR inhibitor. These results

Published in: "Angewandte Chemie International Edition".

Synergistic Palladium/Copper‐Catalyzed 1,4‐Difunctionalization of 1,3‐Dienes for Stereodivergent Construction of 1,5‐Nonadjacent Stereocenters

2024-03-22T13:08:32+00:00March 22nd, 2024|Categories: Publications|

The construction of two distal stereocenters through a single catalytic process is of great interest in organic synthesis. While there are some successful reports regarding stereodivergent preparation of 1,3- or 1,4-stereocenters, the more challenged 1,5-nonadjacent stereocenters have never been achieved in a stereodivergent fashion. Herein we describe a synergistic palladium/copper catalysis for 1,4-difunctionalization reactions of 1,3-dienes, providing access to 1,5-nonadjacent quaternary stereocenters. Because each of the two catalysts separately controlled one of the newly formed stereocenters, stereodivergent synthesis of all four diastereomers of the products could readily be achieved simply by choosing an appropriate combination of chiral catalysts. Experimental and computational studies supported a mechanism involving a Heck/Tsuji–Trost cascade reaction, and the origins of the stereoselectivity were elucidated.

Published in: "Angewandte Chemie International Edition".

Hydrogen Evolution in Neutral Media by Differential Intermediate Binding at Charge‐modulated Sites of a Bimetallic Alloy Electrocatalyst

2024-03-22T13:08:31+00:00March 22nd, 2024|Categories: Publications|Tags: |

The energy barrier to dissociate neutral water has been lowered by the differential intermediate binding on the charge-modulated metal centers of Co85Mo15 sheets supported on Ni-foam (NF), where the overpotential for hydrogen evolution reaction (HER) in 1M phosphate buffer solution (PBS) is only 50 ± 9 mV at -10 mA cm-2. It has a turnover frequency (TOF) of 0.18 s-1, mass activity of 13.2 A g-1 at -200 mV vs. reversible hydrogen electrode (RHE), and produces 16 ml H2 h-1 at -300 mV vs. RHE, more than double that of 20% Pt/C. The Mod+ and Cod- sites adsorb OH*, and H*, respectively, and the electron injection from Co to H-O-H cleaves the O-H bond to form the Mo-OH* intermediate. Operando spectral analyses indicate a weak H-bonded network for facilitating the H2O*/OH* transport, and a potential-induced reversal of the charge density from Co to the more electronegative Mo, because of the electron withdrawing Co-H* and Mo-OH* species. Co85Mo15/NF can also drive the complete electrolysis of neutral water at only 1.73 V (10 mA cm-2). In alkaline, and acidic media, it demonstrates a Pt-like HER activity, accomplishing -1000 mA cm-2 at overpotentials of 161 ± 7, and 175 ± 22 mV, respectively.

Published in: "Angewandte Chemie International Edition".

Alkyl–π Functional Molecular Gels: Control of Elastic Modulus and Improvement of Electret Performance

2024-03-22T13:08:27+00:00March 22nd, 2024|Categories: Publications|

The development of optoelectronically-active soft materials is drawing attention to the application of soft electronics. A room-temperature solvent-free liquid obtained by modifying a π-conjugated moiety with flexible yet bulky alkyl chains is a promising functional soft material. Tuning the elastic modulus (G′) is essential for employing optoelectronically-active alkyl–π liquids in deformable devices. However, the range of G′ achieved through the molecular design of alkyl–π liquids is limited. We report herein a method for controlling G′ of alkyl–π liquids by gelation. Adding 1 wt% low-molecular-weight gelator formed the alkyl–π functional molecular gel (FMG) and increased G′ of alkyl–π liquids by up to seven orders of magnitude while retaining the optical properties. Because alkyl–π FMGs have functional π-moieties in the gel medium, this new class of gels has a much higher content of π-moieties of up to 59 wt% compared to conventional π-gels of only a few wt%. More importantly, the gel state has a 23% higher charge-retention capacity than the liquid, providing better performance in deformable mechanoelectric generator-electret devices. The strategy used in this study is a novel approach for developing next-generation optoelectronically-active FMG materials.

Published in: "Angewandte Chemie International Edition".

Optimizing Molecular Crystallinity and Suppressing Electron‐Phonon Coupling in Completely Non‐fused Ring Electron Acceptors for Organic Solar Cells

2024-03-19T13:08:06+00:00March 19th, 2024|Categories: Publications|

High open-circuit voltage (VOC) organic solar cells (OSCs) have received increasing attention because of their promising application in tandem device and indoor photovoltaic. However, the lack of a precise correlation between molecular structure and stacking behaviors of wide bandgap electron acceptors has greatly limited its development. Here, we adopted an asymmetric halogenation strategy (AHS) and synthesized two completely non-fused ring electron acceptors (NFREAs), HF-BTA33 and HCl-BTA33. The results show that AHS significantly enhances the molecular dipoles and suppresses electron-phonon coupling, resulting in enhanced intramolecular/intermolecular interactions and decreased nonradiative decay. As a result, PTQ10:HF-BTA33 realizes a power conversion efficiency (PCE) of 11.42% with a VOC of 1.232 V, higher than that of symmetric analogue F-BTA33 (PCE=10.02%, VOC=1.197 V). Notably, PTQ10:HCl-BTA33 achieves the highest PCE of 12.54% with a VOC of 1.201 V due to the long-range ordered π-π packing and enhanced surface electrostatic interactions thereby facilitating exciton dissociation and charge transport. This work not only proves that asymmetric halogenation of completely NFREAs is a simple and effective strategy for achieving both high PCE and VOC, but also provides deeper insights for the precise molecular design of low cost completely NFREAs.

Published in: "Angewandte Chemie International Edition".

Light‐Regulated Nucleation for Growing Highly Uniform Single‐Crystalline Microrods

2024-03-19T13:08:02+00:00March 19th, 2024|Categories: Publications|

We report a light-irradiation method to control the synchronous nucleation of a donor-acceptor (D-A) fluorophore for growing highly uniform single-crystalline microrods, which is in sharp contrast to the prevailing methods of inhibiting spontaneous nucleation and additionally adding seeds. The D-A fluorophore was observed to undergo photoinduced electron transfer to CrCl3, leading to the generation of HCl and the subsequent protonation of the D-A fluorophore. By intensifying photoirradiation or prolonging its duration, the concentration of protonated D-A fluorophores can be rapidly increased to a high supersaturation level. This results in the formation of a controlled number of nuclei in a synchronous manner, which in turn kickstart the epitaxial growth of protonated D-A fluorophores towards uniform single-crystalline microrods of controlled sizes.  The light-regulated synchronous nucleation and uniform growth of microrods are a unique phenomenon that can only be achieved by specific Lewis acids, making it a novel probing method for sensitively detecting strong Lewis acids such as chromium chloride.

Published in: "Angewandte Chemie International Edition".

Light‐Driven C−C Coupling for Targeted Synthesis of CH3COOH with Nearly 100 % Selectivity from CO2

2024-03-19T13:08:00+00:00March 19th, 2024|Categories: Publications|Tags: |

The CO2 photoreduction towards CH3COOH with nearly 100 % selectivity is realized over a catalyst with charge asymmetric metal pair sites, wherein the metal charge asymmetric active sites induced by doping engineering can boost the C−C coupling of double COOH* intermediates. Abstract Targeted synthesis of acetic acid (CH3COOH) from CO2 photoreduction under mild conditions mainly limits by the kinetic challenge of the C−C coupling. Herein, we utilized doping engineering to build charge-asymmetrical metal pair sites for boosted C−C coupling, enhancing the activity and selectivity of CO2 photoreduction towards CH3COOH. As a prototype, the Pd doped Co3O4 atomic layers are synthesized, where the established charge-asymmetrical cobalt pair sites are verified by X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy spectra. Theoretical calculations not only reveal the charge-asymmetrical cobalt pair sites caused by Pd atom doping, but also manifest the promoted C−C coupling of double *COOH intermediates through shortening of the coupled C−C bond distance from 1.54 to 1.52 Å and lowering their formation energy barrier from 0.77 to 0.33 eV. Importantly, the decreased reaction energy barrier from the protonation of two*COOH into *CO intermediates for the Pd-Co3O4 atomic layer slab is 0.49 eV, higher than that of the Co3O4 atomic layer slab (0.41 eV). Therefore, the Pd-Co3O4 atomic layers exhibit the CH3COOH evolution rate of ca. 13.8 μmol g−1 h−1 with near 100% selectivity, both of which outperform all previously reported single photocatalysts for CO2 photoreduction towards CH3COOH under similar conditions.

Published in: "Angewandte Chemie International Edition".

Stereodivergent, Kinetically Controlled Isomerization of Terminal Alkenes via Nickel Catalysis

2024-03-18T13:09:30+00:00March 18th, 2024|Categories: Publications|

Because internal alkenes are more challenging synthetic targets than terminal alkenes, metal-catalyzed olefin mono-transposition (i.e., positional isomerization) approaches have emerged to afford valuable E- or Z- internal alkenes from their complementary terminal alkene feedstocks. However, the applicability of these methods has been hampered by lack of generality, commercial availability of precatalysts, and scalability. Here, we report a nickel-catalyzed platform for the stereodivergent E/Z-selective synthesis of internal alkenes at room temperature. Commercial reagents enable this one-carbon transposition of terminal alkenes to valuable E- or Z-internal alkenes via a Ni–H-mediated insertion/elimination mechanism. Though the mechanistic regime is the same in both systems, the underlying pathways that lead each of the active catalysts are distinct, with the Z-selective catalyst forming from comproportionation of an oxidative addition complex followed by oxidative addition with substrate and the E-selective catalyst forming from protonation of the metal by the trialkylphosphonium salt additive. In each case, ligand sterics and denticity control stereochemistry and prevent over-isomerization.

Published in: "Angewandte Chemie International Edition".

Upcycling of Carbon Fiber/Thermoset Composites into High‐Performance Elastomers and Repurposed Carbon Fibers

2024-03-16T13:08:01+00:00March 16th, 2024|Categories: Publications|Tags: |

Recycling of carbon fiber-reinforced polymer composites (CFRCs) based on thermosetting plastics is difficult. In the present study, high-performance CFRCs are fabricated through complexation of aromatic pinacol-cross-linked polyurethane (PU-AP) thermosets with carbon fiber (CF) cloths. PU-AP thermosets exhibit a breaking strength of 95.5 MPa and toughness of 473.6 MJ m-3 and contain abundant hydrogen-bonding groups, which can have strong adhesion with CFs. Because of the high interfacial adhesion between CF cloths and PU-AP thermosets and high toughness of PU-AP thermosets, CF/PU-AP composites possess a high tensile strength of >870 MPa. Upon heating in N,N-dimethylacetamide (DMAc) at 100 °C, the aromatic pinacols in the CF/PU-AP composites can be cleaved, generating non-destructive CF cloths and linear polymers that can be converted to high-performance elastomers. The elastomers are mechanically robust, healable, reprocessable, and damage-resistant with an extremely high tensile strength of 74.2 MPa and fracture energy of 149.6 kJ m-2. As a result, dissociation of CF/PU-AP composites enables the recovery of reusable CF cloths and high-performance elastomers, thus realizing the upcycling of CF/PU-AP composites.

Published in: "Angewandte Chemie International Edition".

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