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novembre 2022 – ChemDigest

Mois : novembre 2022

A Platinum(II)‐Based Molecular Cage with Aggregation‐Induced Emission for Enzymatic Photocyclization of Alkynylaniline

A Platinum(II)-Based Molecular Cage with Aggregation-Induced Emission for Enzymatic Photocyclization of Alkynylaniline

The photocyclization of alkynylanilines catalyzed by an aggregated PtII-based octahedral cage has been shown to mimic bio-enzyme catalysis by aggregated biological macromolecules. The aggregated supramolecular species exhibits a higher photocatalytic efficiency than dispersed metal-organic cages without aggregation.

Abstract

Enzymes facilitate chemical conversions through the collective activity of aggregated components, but the marriage of aggregation-induced emission (AIE) with molecular containers to emulate enzymatic conversion remains challenging. Herein, we report a new approach to construct a PtII-based octahedral cage with AIE characteristics for the photocyclization of alkynylaniline by restricting the rotation of the pendant phenyl rings peripheral to the PtII corner. With the presence of water, the C−H⋅⋅⋅π interactions involving the triphenylphosphine fragments resulted in aggregation of the molecular cages into spherical particles and significantly enhanced the PtII-based luminescence. The kinetically inert Pt-NP chelator, with highly differentiated redox potentials in the ground and excited states, and the efficient coordination activation of the platinum corner facilitated excellent catalysis of the photocyclization of alkynylaniline. The enzymatic kinetics and the advantages of binding and activating substrates in an aqueous medium provide a new avenue to develop mimics for efficient photosynthesis.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Zhong Wei, Xu Jing, Yang Yang, Jiayou Yuan, Mingxu Liu, Cheng He, Chunying Duan
onlinelibrary.wiley.com/doi/10.1002/anie.202214577

α‐Synuclein as a Target for Metallo‐Anti‐Neurodegenerative Agents

α-Synuclein as a Target for Metallo-Anti-Neurodegenerative Agents

The RuIII complex NAMI-A is activated by hydrolysis and then reacts with specific amino acids in the abundant brain protein α-synuclein, preventing and disassembling α-synuclein fibrils, abolishing toxicity toward neuronal cells, and mitigating neurodegeneration and motor impairments in a model of Parkinson’s. Since NAMI-A has a pharmaceutically-acceptable profile, it has potential for use in treatment of neurodegenerative conditions.

Abstract

The unique thermodynamic and kinetic coordination chemistry of ruthenium allows it to modulate key adverse aggregation and membrane interactions of α-synuclein (α-syn) associated with Parkinson’s disease. We show that the low-toxic RuIII complex trans-[ImH][RuCl4(Me2SO)(Im)] (NAMI-A) has dual inhibitory effects on both aggregation and membrane interactions of α-syn with submicromolar affinity, and disassembles pre-formed fibrils. NAMI-A abolishes the cytotoxicity of α-syn towards neuronal cells and mitigates neurodegeneration and motor impairments in a rat model of Parkinson’s. Multinuclear NMR and MS analyses show that NAMI-A binds to residues involved in protein aggregation and membrane binding. NMR studies reveal the key steps in pro-drug activation and the effect of activated NAMI-A species on protein folding. Our findings provide a new basis for designing ruthenium complexes which could mitigate α-syn-induced Parkinson’s pathology differently from organic agents.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Kaiming Cao, Yang Zhu, Zhuanghao Hou, Manman Liu, Yanyan Yang, Hongze Hu, Yi Dai, Yu Wang, Siming Yuan, Guangming Huang, Jiaming Mei, Peter J. Sadler, Yangzhong Liu
onlinelibrary.wiley.com/doi/10.1002/anie.202215360

Reversible Switching CuII/CuI Single Sites Catalyze High‐rate and Selective CO2 Photoreduction

Reversible Switching CuII/CuI Single Sites Catalyze High-rate and Selective CO2 Photoreduction

In this work, reversible redox-switching CuII/CuI single sites confined in Cu-MOF single-unit-cell sheets were used in the CO2 photoreduction to CO.

Abstract

Herein, we first design a model of reversible redox-switching metal–organic framework single-unit-cell sheets, where the abundant metal single sites benefit for highly selective CO2 reduction, while the reversible redox-switching metal sites can effectively activate CO2 molecules. Taking the synthetic Cu-MOF single-unit-cell sheets as an example, synchrotron-radiation quasi in situ X-ray photoelectron spectra unravel the reversible switching CuII/CuI single sites initially accept photoexcited electrons and then donate them to CO2 molecules, which favors the rate-liming activation into CO2δ−, verified by in situ FTIR spectra and Gibbs free energy calculations. As an outcome, Cu-MOF single-unit-cell sheets achieve near 100 % selectivity for CO2 photoreduction to CO with a high rate of 860 μmol g−1 h−1 without any sacrifice reagent or photosensitizer, where both the activity and selectivity outperform previously reported photocatalysts evaluated under similar conditions.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xiaolong Zu, Yuan Zhao, Xiaodong Li, Runhua Chen, Weiwei Shao, Li Li, Panzhe Qiao, Wensheng Yan, Yang Pan, Qian Xu, Junfa Zhu, Yongfu Sun, Yi Xie
onlinelibrary.wiley.com/doi/10.1002/anie.202215247

In Vivo Biocatalytic Cascades Featuring an Artificial‐Enzyme‐Catalysed New‐to‐Nature Reaction

In Vivo Biocatalytic Cascades Featuring an Artificial-Enzyme-Catalysed New-to-Nature Reaction**

We report in vivo biocatalytic cascade reactions comprising a combination of canonical enzyme-catalysed reactions with an artificial-enzyme-catalysed new-to-nature reaction. The artificial enzyme contains a genetically encoded unnatural catalytic residue, which catalyses the formation of a hydrazone product from biosynthetically produced benzaldehydes in E. coli.

Abstract

Artificial enzymes utilizing the genetically encoded non-proteinogenic amino acid p-aminophenylalanine (pAF) as a catalytic residue are able to react with carbonyl compounds through an iminium ion mechanism to promote reactions that have no equivalent in nature. Herein, we report an in vivo biocatalytic cascade that is augmented with such an artificial enzyme-catalysed new-to-nature reaction. The artificial enzyme in this study is a pAF-containing evolved variant of the lactococcal multidrug-resistance regulator, designated LmrR_V15pAF_RMH, which efficiently converts benzaldehyde derivatives produced in vivo into the corresponding hydrazone products inside E. coli cells. These in vivo biocatalytic cascades comprising an artificial-enzyme-catalysed reaction are an important step towards achieving a hybrid metabolism.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Linda Ofori Atta, Zhi Zhou, Gerard Roelfes
onlinelibrary.wiley.com/doi/10.1002/anie.202214191

Rhodium Single‐Atom Catalyst Design through Oxide Support Modulation for Selective Gas‐Phase Ethylene Hydroformylation

Rhodium Single-Atom Catalyst Design through Oxide Support Modulation for Selective Gas-Phase Ethylene Hydroformylation

Engineering the direct metal coordination environment in single-atom catalysts, via adjustment of the oxide surface chemistry, is a powerful strategy towards reactivity modulation. An energetically facile depletion of surface oxygen on a Rh1/SnO2 catalyst unlocks an exceptional performance in the gas-phase hydroformylation of ethylene with syngas, hitherto exclusive of molecular catalysts operating in liquid environments.

Abstract

A frontier challenge in single-atom (SA) catalysis is the design of fully inorganic sites capable of emulating the high reaction selectivity traditionally exclusive of organometallic counterparts in homogeneous catalysis. Modulating the direct coordination environment in SA sites, via the exploitation of the oxide support’s surface chemistry, stands as a powerful albeit underexplored strategy. We report that isolated Rh atoms stabilized on oxygen-defective SnO2 uniquely unite excellent TOF with essentially full selectivity in the gas-phase hydroformylation of ethylene, inhibiting the thermodynamically favored olefin hydrogenation. Density Functional Theory calculations and surface characterization suggest that substantial depletion of the catalyst surface in lattice oxygen, energetically facile on SnO2, is key to unlock a high coordination pliability at the mononuclear Rh centers, leading to an exceptional performance which is on par with that of molecular catalysts in liquid media.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Marcos G. Farpón, Wilson Henao, Philipp N. Plessow, Eva Andrés, Raúl Arenal, Carlo Marini, Giovanni Agostini, Felix Studt, Gonzalo Prieto
onlinelibrary.wiley.com/doi/10.1002/anie.202214048

Encapsulating Metal Nanoparticles into a Layered Zeolite Precursor with Surface Silanol Nests Enhances Sintering Resistance

Encapsulating Metal Nanoparticles into a Layered Zeolite Precursor with Surface Silanol Nests Enhances Sintering Resistance**

IPC-1P, a layered zeolite precursor with a relatively high density of surface silanols can be swollen using docosyltrimethylammonium hydroxide and functionalized with ultra-small Rh nanoparticles. The resulting mesoporous zeolitic material Rh@IPC_C22 has a high layer disordering without microporosity. In situ heating STEM imaging and DFT simulations show strong metal-silanol interactions stabilizing Rh nanoparticles against thermal sintering.

Abstract

Supported metal nanoparticles are used as heterogeneous catalysts but often deactivated due to sintering at high temperatures. Confining metal species into a porous matrix reduces sintering, yet supports rarely provide additional stabilization. Here, we used the silanol-rich layered zeolite IPC-1P to stabilize ultra-small Rh nanoparticles. By adjusting the IPC-1P interlayer space through swelling, we prepared various architectures, including microporous and disordered mesoporous. In situ scanning transmission electron microscopy confirmed that Rh nanoparticles are resistant to sintering at high temperature (750 °C, 6 hrs). Rh clusters strongly bind to surface silanol quadruplets at IPC-1P layers by hydrogen transfer to clusters, while high silanol density hinders their migration based on density functional theory calculations. Ultimately, combining swelling with long-chain surfactant and utilizing metal-silanol interactions resulted in a novel, catalytically active material—Rh@IPC_C22.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Ang Li, Yuyan Zhang, Christopher J. Heard, Kinga Gołąbek, Xiaohui Ju, Jiří Čejka, Michal Mazur
onlinelibrary.wiley.com/doi/10.1002/anie.202213361

Imaging Photoelectron Circular Dichroism in the Detachment of Mass‐Selected Chiral Anions

Imaging Photoelectron Circular Dichroism in the Detachment of Mass-Selected Chiral Anions

Energy-resolved Photoelectron Circular Dichroism (PECD) is demonstrated in the photoelectron spectroscopy of mass-selected deprotonated 1-indanol anionic ([Ind-H]) enantiomers. A unique PECD signature is observed for several isomers and detachment channels of [Ind-H]. This work supports the use of anions for future analytical methods of enantiomeric discrimination, and allows for insight into the influence of short-range interactions on PECD.

Abstract

Photoelectron Circular Dichroism (PECD) is a forward-backward asymmetry in the photoemission from a non-racemic sample induced by circularly polarized light. PECD spectroscopy has potential analytical advantages for chiral discrimination over other chiroptical methods due to its increased sensitivity to the chiral potential of the molecule. The use of anions for PECD spectroscopy allows for mass-selectivity and provides a path to simple experimental schemes that employ table-top light sources. Evidence of PECD for anions is limited, and insight into the forces that govern PECD electron dynamics in photodetachment is absent. Here, we demonstrate a PECD effect in the photodetachment of mass-selected deprotonated 1-indanol anions. By utilizing velocity map imaging photoelectron spectroscopy with a tunable light source, we determine the energy-resolved PECD over a wide range of photon energies. The observed PECD reaches up to 11 %, similar to what has been measured for neutral species.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jenny Triptow, André Fielicke, Gerard Meijer, Mallory Green
onlinelibrary.wiley.com/doi/10.1002/anie.202212020

Optimization of G‐Quadruplex Ligands through a SAR Study Combining Parallel Synthesis and Screening of Cationic Bis(acylhydrazones)

Optimization of G-Quadruplex Ligands through a SAR Study Combining Parallel Synthesis and Screening of Cationic Bis(acylhydrazones)

Ready to screen. A library of cationic bis(acylhydrazones) as putative G4-DNA ligands was prepared by a straightforward condensation of the corresponding building blocks. Screening the resulting samples (without any isolation or purification steps) by fluorescence-melting experiments identified three novel hits, whose interactions with G4-DNA targets were studied in detail by several biophysical methods and molecular modeling.

Abstract

G-quadruplexes (G4s), secondary structures adopted by guanine-rich DNA and RNA sequences, are implicated in numerous biological processes and have been suggested as potential drug targets. Accordingly, there is an increasing interest in developing high-throughput methods that allow the generation of congeneric series of G4-targeting molecules (“ligands”) and investigating their interactions with the targets. We have developed an operationally simple method of parallel synthesis to generate “ready-to-screen” libraries of cationic acylhydrazones, a motif that we have previously identified as a promising scaffold for potent, biologically active G4 ligands. Combined with well-established screening techniques, such as fluorescence melting, this method enables the rapid synthesis and screening of combinatorial libraries of potential G4 ligands. Following this protocol, we synthesized a combinatorial library of 90 bis(acylhydrazones) and screened it against five different nucleic acid structures. This way, we were able to analyze the structure–activity relationships within this series of G4 ligands, and identified three novel promising ligands whose interactions with G4-DNAs of different topologies were studied in detail by a combination of several biophysical techniques, including native mass spectrometry, and molecular modeling.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Oksana Reznichenko, Denis Leclercq, Jaime Franco Pinto, Liliane Mouawad, Valérie Gabelica, Anton Granzhan
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202202427

The Marriage of Sierpiński Triangles and Platonic Polyhedra

The Marriage of Sierpiński Triangles and Platonic Polyhedra

A powerful multicomponent self-assembly strategy has been developed that allows access to gorgeous 3D architectures with large cavities and high complexity. This approach has led to the synthesis of a Sierpiński tetrahedron and a Sierpiński octahedron with Sierpiński triangles as the panels. These two discrete complexes, with molecular weights up to 55 kDa and diameters up to 7.4 nm, were formed in near-quantitative yields.

Abstract

Fractal structures with self-similarity are of fundamental importance in the fields of aesthetic, chemistry and mathematics. Here, by taking advantage of constructs the rational geometry-directed precursor design, we report the construction of two fascinating Platonic solids, the Sierpiński tetrahedron ST-T and the Sierpiński octahedron ST-O, in which each possesses a fractal Sierpiński triangle on their independent faces. These two discrete complexes are formed in near-quantitative yield from the multi-component self-assembly of truncated Sierpiński triangular kernel L1 with tribenzotriquinacene-based hexatopic and anthracene-based tetratopic terpyridine ligands (L3 and L4) in the presence of metal ions, respectively. The enhanced stabilities of the 3D discrete structures were investigated by gradient tandem mass spectrometry (gMS2). This work provides new constructs for the imitation of complex virus assemblies and for the molecular encapsulation of giant guest molecules.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jun Wang, Zhilong Jiang, Weiya Liu, Zihao Wu, Rui Miao, Fan Fu, Jia‐Fu Yin, Bangtang Chen, Qiangqiang Dong, He Zhao, Kaixiu Li, Guotao Wang, Die Liu, Panchao Yin, Yiming Li, Mingzhao Chen, Pingshan Wang
onlinelibrary.wiley.com/doi/10.1002/anie.202214237

Donor‐Acceptor Cyclopropanes: Activation Enabled by a Single, Vinylogous Acceptor

Donor-Acceptor Cyclopropanes: Activation Enabled by a Single, Vinylogous Acceptor

A new class of donor-acceptor cyclopropanes bearing only a single, vinylogous acceptor moiety is presented. The system is capable of cycloadditions through Brønsted or Lewis acid catalysis with numerous reagents: aldehydes, ketones, thioketones, nitriles, naphth-2-ols, cyclopropanes, nitrones and isobenzofurans. The mechanism was explored in detail by kinetic and mechanistic experiments.

Abstract

A novel class of highly activated donor-acceptor cyclopropanes bearing only a single, vinylogous acceptor is presented. These strained moieties readily undergo cycloadditions with aldehydes, ketones, thioketones, nitriles, naphth-2-ols and various other substrates to yield the corresponding carbo- and heterocycles. Diastereocontrol can be achieved through the choice of catalyst (Brønsted or Lewis acid). The formation of tetrahydrofurans was shown to be highly enantiospecific when chiral cyclopropanes are employed. A series of mechanistic and kinetic experiments was conducted to elucidate a plausible catalytic cycle and to rationalize the stereochemical outcome.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Nils L. Ahlburg, Oliver Hergert, Peter G. Jones, Daniel B. Werz
onlinelibrary.wiley.com/doi/10.1002/anie.202214390

Aluminium‐Catalyzed Selective Hydroboration of Esters and Epoxides to Alcohols: C−O Bond Activation

Aluminium-Catalyzed Selective Hydroboration of Esters and Epoxides to Alcohols: C−O Bond Activation

The CBG aluminium-dihydride (I) is used as a catalyst for reducing esters with good tolerance of reducible functionalities. Furthermore, it was demonstrated that compound I catalyzed the hydroboration of epoxides into Markovnikov-branched products. The earth-abundant, non-toxic, and inexpensive Al-based catalysts are attractive and alternatives to expensive transition and lanthanide-based metal catalysts.

Abstract

In this work, the molecular aluminium dihydride complex bearing an N, N’-chelated conjugated bis-guanidinate (CBG) ligand is used as a catalyst for reducing a wide range of aryl and alkyl esters with good tolerance of alkene (C=C), alkyne (C≡C), halides (Cl, Br, I and F), nitrile (C≡N), and nitro (NO2) functionalities. Further, we investigated the catalytic application of aluminium dihydride in the C−O bond cleavage of alkyl and aryl epoxides into corresponding branched Markovnikov ring-opening products. In addition, the chemoselective intermolecular reduction of esters over other reducible functional groups, such as amides and alkenes, has been established. Intermediates are isolated and characterized by NMR and HRMS studies, which confirm the probable catalytic cycles for the hydroboration of esters and epoxides.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Nabin Sarkar, Rajata Kumar Sahoo, Sharanappa Nembenna
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202203023

Bioinspired Gradient Stretchable Aerogels for Ultrabroad‐Range‐Response Pressure‐Sensitive Wearable Electronics and High‐Efficient Separators

Bioinspired Gradient Stretchable Aerogels for Ultrabroad-Range-Response Pressure-Sensitive Wearable Electronics and High-Efficient Separators

Gradient, stretchable and superelastic reduced graphene oxide/polyurethane nanocomposite aerogels have been achieved by a sol-gel/hot pressing/freeze casting/ambient pressure drying strategy. The gradient aerogels can be used for high-efficient separators and wearable electronics with an ultrabroad detection range of 1 Pa–12.6 MPa and ultrahigh fatigue resistance, showing great potentials in high-performance sensors and separators.

Abstract

Broad-range-response pressure-sensitive wearable electronics are urgently needed but their preparation remains a challenge. Herein, we report unprecedented bioinspired wearable electronics based on stretchable and superelastic reduced graphene oxide/polyurethane nanocomposite aerogels with gradient porous structures by a sol-gel/hot pressing/freeze casting/ambient pressure drying strategy. The gradient structure with a hot-pressed layer promotes strain transfer and resistance variation under high pressures, leading to an ultrabroad detection range of 1 Pa–12.6 MPa, one of the broadest ranges ever reported. They can withstand 10 000 compression cycles under 1 MPa, which can’t be achieved by traditional flexible pressure sensors. They can be applied for broad-range-response electronic skins and monitoring various physical signals/motions and ultrahigh pressures of automobile tires. Moreover, the gradient aerogels can be used as high-efficient gradient separators for water purification.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xiaoyu Zhang, Zhenyu Hu, Qi Sun, Xing Liang, Puzhong Gu, Jia Huang, Guoqing Zu
onlinelibrary.wiley.com/doi/10.1002/anie.202213952

Highly Enantioselective Brønsted Acid Catalyzed Heyns Rearrangement

Highly Enantioselective Brønsted Acid Catalyzed Heyns Rearrangement

The first method for highly enantioselective Brønsted acid catalyzed Heyns rearrangement reactions, featuring low catalyst loadings, high yields, high enantioselectivities, good functional-group tolerance, and broad substrate scope has been developed. The method is efficient, delivering various chiral amines, including some biologically active molecules.

Abstract

Herein we report the first method for highly enantioselective Brønsted acid catalyzed Heyns rearrangements. These reactions, catalyzed by a chiral spiro phosphoric acid, afforded synthetically valuable chiral α-aryl-α-aminoketones which cannot be obtained by means of previously reported Heyns rearrangement methods. This method features low catalyst loadings, high yields and high enantioselectivities, making these reactions highly practical. We used the method to efficiently synthesize various chiral amines, including some biologically active molecules. We experimentally proved that these acid-catalyzed Heyns rearrangements proceeded via a proton-transfer process involving an enol intermediate and the stereocontrol was realized during the proton-transfer step.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Jin Cao, Yu‐Xuan Su, Xin‐Yu Zhang, Shou‐Fei Zhu
onlinelibrary.wiley.com/doi/10.1002/anie.202212976

Tunable Strategy for the Asymmetric Synthesis of Sulfoglycolipids from Mycobacterium tuberculosis To Elucidate the Structure and Immunomodulatory Property Relationships

Tunable Strategy for the Asymmetric Synthesis of Sulfoglycolipids from Mycobacterium tuberculosis To Elucidate the Structure and Immunomodulatory Property Relationships

A tunable asymmetric strategy for the synthesis of sulfoglycolipids (SGLs) was developed. The strategy features a suite of asymmetrically protected trehaloses for acylation and sulfation. A practical synthetic route was explored for the preparation of polydeoxypropionate fatty acids, which together with the trehaloses enabled the synthesis of different classes of SGLs for immunological studies.

Abstract

We developed a versatile asymmetric strategy to synthesize different classes of sulfoglycolipids (SGLs) from Mycobacterium tuberculosis. The strategy features the use of asymmetrically protected trehaloses, which were acquired from the glycosylation of TMS α-glucosyl acceptors with benzylidene-protected thioglucosyl donors. The positions of the protecting groups at the donors and acceptors can be fine-tuned to obtain different protecting-group patterns, which is crucial for regioselective acylation and sulfation. In addition, a chemoenzymatic strategy was established to prepare the polymethylated fatty acid building blocks. The strategy employs inexpensive lipase as a desymmetrization agent in the preparation of the starting substrate and readily available chiral oxazolidinone as a chirality-controlling agent in the construction of the polymethylated fatty acids. A subsequent investigation on the immunomodulatory properties of each class of SGLs showed how the structures of SGLs impact the host innate immunity response.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Soumik Mondal, Chieh‐Jen Tseng, Janet Jia‐Yin Tan, Ding‐Yuan Lin, Hsien‐Ya Lin, Jui–Hsia Weng, Chun‐Hung Lin, Kwok‐Kong Tony Mong
onlinelibrary.wiley.com/doi/10.1002/anie.202212514

Imine Directed Cp*RhIII‐Catalyzed N−H Functionalization and Annulation with Amino Amides, Aldehydes, and Diazo Compounds

Imine Directed Cp*RhIII-Catalyzed N−H Functionalization and Annulation with Amino Amides, Aldehydes, and Diazo Compounds

A multicomponent, imine directed Cp*RhIII-catalyzed N−H functionalization/annulation is reported. This method represents the first example of multicomponent N−H functionalization and allows for rapid access to a heterocyclic product. Further transformations and a plausible mechanism based on X-ray crystallographic characterization of a catalytically competent rhodacycle intermediate are disclosed.

Abstract

A multicomponent annulation that proceeds by imine directed Cp*RhIII-catalyzed N−H functionalization is disclosed. The transformation affords piperazinones displaying a range of functionality and is the first example of transition metal-catalyzed multicomponent N−H functionalization. A broad range of readily available α-amino amides, including those derived from glycine, α-substituted, and α,α-disubstituted amino acids, were effective inputs and enabled the incorporation of a variety of amino acid side chains with minimal racemization. Branched and unbranched alkyl aldehydes and various stabilized diazo compounds were also efficient reactants. The piperazinone products were further modified through efficient transformations. Mechanistic studies, including X-ray crystallographic characterization of a catalytically competent five-membered rhodacycle with imine and amide nitrogen chelation, provide support for the proposed mechanism.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Adam J. Zoll, Jenna C. Molas, Brandon Q. Mercado, Jonathan A. Ellman
onlinelibrary.wiley.com/doi/10.1002/anie.202210822

Metal‐like Charge Transport in PEDOT(OH) Films by Post‐processing Side Chain Removal from a Soluble Precursor Polymer

Metal-like Charge Transport in PEDOT(OH) Films by Post-processing Side Chain Removal from a Soluble Precursor Polymer

Functionalization of poly(3,4-ethylenedioxythiophene) (PEDOT) with ester-based side chains allow for solution processing and moderate electrical conductivity. Hydrolysis of these side chains leaves hydroxymethyl functional groups on the polymer, increases the relative amount of electroactive material, significantly increases electrical conductivity to greater than 1000 S cm−1, and changes the transport mechanism from hopping-like to metal-like.

Abstract

Herein, a route to produce highly electrically conductive doped hydroxymethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) films, termed PEDOT(OH) with metal-like charge transport properties using a fully solution processable precursor polymer is reported. This is achieved via an ester-functionalized PEDOT derivative [PEDOT(EHE)] that is soluble in a range of solvents with excellent film-forming ability. PEDOT(EHE) demonstrates moderate electrical conductivities of 20–60 S cm−1 and hopping-like (i.e., thermally activated) transport when doped with ferric tosylate (FeTos3). Upon basic hydrolysis of PEDOT(EHE) films, the electrically insulative side chains are cleaved and washed from the polymer film, leaving a densified film of PEDOT(OH). These films, when optimally doped, reach electrical conductivities of ≈1200 S cm−1 and demonstrate metal-like (i.e., thermally deactivated and band-like) transport properties and high stability at comparable doping levels.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: James F. Ponder, Shawn A. Gregory, Amalie Atassi, Abigail A. Advincula, Joshua M. Rinehart, Guillaume Freychet, Gregory M. Su, Shannon K. Yee, John R. Reynolds
onlinelibrary.wiley.com/doi/10.1002/anie.202211600

A Polyfluoroalkyl‐Containing Non‐fullerene Acceptor Enables Self‐Stratification in Organic Solar Cells

A Polyfluoroalkyl-Containing Non-fullerene Acceptor Enables Self-Stratification in Organic Solar Cells

A polyfluoroalkyl-containing guest acceptor (EH-C8F17) enables self-stratification in the active layer of bulk-heterojunction organic solar cells. The favorable vertical phase separation and molecular stacking increases the mobility, increases carrier lifetimes, and reduces trap-assisted recombination, leading to significantly improved device performance.

Abstract

The elaborate control of the vertical phase distribution within an active layer is critical to ensuring the high performance of organic solar cells (OSCs), but is challenging. Herein, a self-stratification active layer is realised by adding a novel polyfluoroalkyl-containing non-fullerene small-molecule acceptor (NFSMA), EH-C8F17, as the guest into PM6:BTP-eC9 blend. A favourable vertical morphology was obtained with an upper acceptor-enriched thin layer and a lower undisturbed bulk heterojunction layer. Consequently, a power conversion efficiency of 18.03 % was achieved, higher than the efficiency of 17.40 % for the device without EH-C8F17. Additionally, benefiting from the improved charge transport and collection realised by this self-stratification strategy, the OSC with a thickness of 350 nm had an impressive PCE of 16.89 %. The results of the study indicate that polyfluoroalkyl-containing NFSMA-assisted self-stratification within the active layer is effective for realising an ideal morphology for high-performance OSCs.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Shihao Chen, Ling Hong, Minghao Dong, Wanyuan Deng, Lin Shao, Yuanqing Bai, Kai Zhang, Chunchen Liu, Hongbin Wu, Fei Huang
onlinelibrary.wiley.com/doi/10.1002/anie.202213869

Perfectly Encoding π‐Conjugated Anions in the RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) Family with Strong Second Harmonic Generation Response and Balanced Birefringence

Perfectly Encoding π-Conjugated Anions in the RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) Family with Strong Second Harmonic Generation Response and Balanced Birefringence

Improving the arrangement of the planar π-conjugated six-membered-ring (C3N3O3)3− anions in the RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) series leads to strong second harmonic generation responses, short UV cutoffs, and moderate birefringence. This finding opens an avenue for designing target materials with balanced linear and nonlinear optical properties which have potential for practical laser applications.

Abstract

Nonlinear optical (NLO) crystal, which simultaneously exhibits strong second-harmonic-generation (SHG) response and desired optical anisotropy, is a core optical material accessible to the modern optoelectronics. Accompanied by strong SHG effect in a NLO crystal, a contradictory problem of overlarge birefringence is ignored, leading to low frequency doubling efficiency and poor beam quality. Herein, a series of rare earth cyanurates RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) were successfully characterized by 3D electron diffraction technique. Based on a “three birds with one stone” strategy, they enable the simultaneous fulfillment of strong SHG responses (2.5–4.2× KH2PO4), short UV cutoff (ca. 220 nm) and applicable birefringence (ca. 0.15 at 800 nm) by the introduction of rare earth coordination control of π-conjugated (C3N3O3)3− anions. These findings provide high-performance short-wavelength NLO materials and highlight the exploration of cyanurates as a new research area.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Xianghe Meng, Xingyu Zhang, Qingxiong Liu, Zhengyang Zhou, Xingxing Jiang, Yonggang Wang, Zheshuai Lin, Mingjun Xia
onlinelibrary.wiley.com/doi/10.1002/anie.202214848

Water‐soluble Self‐assembled {Pd84}Ac Polyoxopalladate Nano‐wheel as a Supramolecular Host

Water-soluble Self-assembled {Pd84}Ac Polyoxopalladate Nano-wheel as a Supramolecular Host

The largest anionic polyoxopalladate ({Pd84}Ac) is shown to act as a water-soluble inorganic host encapsulating organic guests in a Russian Doll fashion. NMR analysis including 1H NMR, Diffusion Ordered Spectroscopy (DOSY) and Nuclear Overhauser Spectroscopy (NOESY), as well as ESI-MS, were used to study the supramolecular chemistry of this system providing conclusive evidence that {Pd84}Ac forms a 1 : 7 host-guest complex with benzyl viologen (BV2+) in aqueous solution.

Abstract

Polyoxopalladates (POPs) are a class of self-assembling palladium-oxide clusters that span a variety of sizes, shapes and compositions. The largest of this family, {Pd84}Ac, is constructed from 14 building units of {Pd6} and lined on the inner and outer torus by 28 acetate ligands. Due to its high water solubility, large hydrophobic cavity and distinct 1H NMR fingerprint {Pd84}Ac is an ideal molecule for exploring supramolecular behaviour with small organic molecules in aqueous media. Molecular visualisation studies highlighted potential binding sites between {Pd84}Ac and these species. Nuclear Magnetic Resonance (NMR) techniques, including 1H NMR, 1H Diffusion Ordered Spectroscopy (DOSY) and Nuclear Overhauser Spectroscopy (NOESY), were employed to study the supramolecular chemistry of this system. Here, we provide conclusive evidence that {Pd84}Ac forms a 1 : 7 host-guest complex with benzyl viologen (BV2+) in aqueous solution.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Zoë L. Sinclair, Nicola L. Bell, Jessica R. Bame, De‐Liang Long, Leroy Cronin
onlinelibrary.wiley.com/doi/10.1002/anie.202214203

Alkyl Formates as Transfer Hydroalkylation Reagents and Their Use in the Catalytic Conversion of Imines to Alkylamines

Alkyl Formates as Transfer Hydroalkylation Reagents and Their Use in the Catalytic Conversion of Imines to Alkylamines**

Alkyl formates can serve as a new class of bifunctional reagents for transfer hydroalkylation reactions. Using a ruthenium(II) catalyst combined with lithium iodide, they can promote the hydroalkylation of imines to amines, with the formation of CO2 as the only by-product.

Abstract

Easily accessible via a simple esterification of alcohols with formic acid, alkyl formates are used as a novel class of transfer hydroalkylation reagents, CO2 acting as a traceless linker. As a proof-of-concept, their reactivity in the transfer hydroalkylation of imines is investigated, using a ruthenium-based catalyst and LiI as promoter to cleave the C−O σ-bond of the formate scaffold. Providing tertiary amines, the reaction displays a divergent regioselectivity compared to previously reported transfer hydroalkylation strategies.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Etienne Crochet, Lucile Anthore‐Dalion, Thibault Cantat
onlinelibrary.wiley.com/doi/10.1002/anie.202214069

Bridged Proteolysis Targeting Chimera (PROTAC) Enables Degradation of Undruggable Targets

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Yan Xiong, Yue Zhong, Hyerin Yim, Xiaobao Yang, Kwang-Su Park, Ling Xie, Poulikos I. Poulikakos, Xiaoran Han, Yue Xiong, Xian Chen, Jing Liu, and Jian Jin
dx.doi.org/https://doi.org/10.1021/jacs.2c09255