Angewandte Chemie最新文献

Various passivation strategies have been explored to enhance the stability of the perovskite solar cells (PSCs). However, the chemical stability of passivators has received limited attention. This study investigates replacing conventional isopropyl alcohol (IPA) with hexafluoroisopropanol (HFIP) as the solvent for depositing passivation layers on perovskite films, offering a novel approach to minimizing defects and improving photovoltaic performance. The unique properties of HFIP, particularly its low pKa and strong proton-donating ability, effectively inhibit the deprotonation of organic ammonia salts. As a result, the HFIP-based passivation solution exhibits enhanced chemical stability, leading to highly reproducible PSCs fabrication. Additionally, perovskite films treated with the HFIP passivation solution demonstrate higher photoluminescence (PL) intensity and longer carrier lifetimes. Consequently, PSCs treated with HFIP-based 1,3-propanediamine dihydroiodide (PDAI) solution achieved a champion power conversion efficiency (PCE) of 26.91% (certified PCE of 26.88%) and maintained 95.9% of their initial efficiency under operational conditions for 1000 h.

In this study, a totally green synthetic protocol was employed to obtain four new donor–acceptor–donor para-azaquinodimethane (pAQM) derivatives to uncover the effect of tuning the push–pull character on their photobehaviour in solution as well as in thin film and in particular on their capability of undergoing singlet fission (SF). The bisthiophene and substituted benzene were used as electron-donor groups at opposite sides of the pAQM electron-acceptor core in asymmetric structures (AsOMe and AsNMe₂), whereas different 5-phenyl thiophene moieties were symmetrically linked to the pAQM core in TPh and TPhOMe. The photoinduced excited state dynamics was investigated in a synergic effort by employing both time resolved optical and electron paramagnetic resonance (EPR) spectroscopies, with the aid of TD-DFT calculations. Our femtosecond transient absorption results showed that intermolecular SF is enabled in the solid state aggregates of these compounds: the fastest and most efficient SF was revealed for the structure with the strongest push–pull degree (AsNMe₂). The other asymmetric molecule (AsOMe) interestingly exhibited higher energetic SF-generated triplet excitons (1.3 eV) than literature SF-materials, as demonstrated by the nanosecond transient absorption sensitization experiments, with possible intriguing implications toward silicon matched SF photovoltaics. Time resolved EPR measurements unveiled the spectral signature of the quintet multiexciton intermediate ⁵(TT) in the pAQM thin films for the first time, to the best of our knowledge, for such unconventional SF materials. The high-spin photoinduced ⁵(TT) appears to be a promising candidate for Quantum Information Science and technologies as a viable molecular spin qudit.

The direct dearomative cycloaddition of pyridines provides a powerful tool to construct medicinally important azabicyclic scaffolds. However, existing methods are limited to accessing isoquinuclidine (2-azabicyclo[2.2.2]octane) cores. Here, we present a formal [4+3] bridged cyclization of pyridines/isoquinolines with vinylcarbenes, enabled by a dearomatization-cycloaddition strategy through a traceless oxazino azaarene intermediate. This method facilitates the efficient construction of previously unexplored bridged azabicyclo[3.2.2]nonatrienes and their benzofused derivatives with high efficiency and excellent chemo-, regio-, and stereoselective control. Furthermore, downstream conversions of the bridgehead imino group enable the synthesis of diverse bridged azabicyclic and heterotricyclic frameworks. Integrated mechanistic studies and computational analyses revealed two distinct cyclization mechanisms for the reaction of oxazino pyridine/isoquinoline intermediates with vinylcarbenes, providing insights into the origins of observed regioselectivity.

Durch Austausch der verbrückenden Carboxylate in DiFe-Suleythrin wird die Koordination des Brückenliganden von 1,3-Carboxylat zu 1,1-Carboxylat verschoben, wodurch alle drei diFe(II)-Koordinationsmotive in einem Protein entstehen. Dies verkürzt den Fe-Fe-Abstand und erhöht die Reaktivität mit O₂. Die Einwirkung von O₂ löst Fe-Umlagerungen aus und erzeugt zwei unterschiedliche diFe(III) (Hydro-)Peroxo-Zwischenprodukte.

The practical application of electrocatalytic CO₂ reduction reaction (CO₂RR) holds a great promise but is hindered by low CO₂ solubility. Under CO₂ mass transfer limitations, the competing hydrogen evolution reaction (HER) is promoted, resulting in a decrease in CO₂RR Faradaic efficiency. Before CO₂ supply reaches its maximum capacity, in neutral or alkaline conditions, increasing CO₂RR selectivity requires additional hydrogen source from solvent H₂O dissociation for CO₂ protonation. However, it is challenging to concurrently achieve CO₂ reduction and H₂O dissociation at single active site. Herein, we synthesized a neighboring Ni-Cr atomic pair configuration with distance of ∼2.7 Å. COMSOL Multiphysics finite-element studies demonstrate that appropriate distance between dual active sites should be on the order of a few angstroms. Operando XAS and soft NEXAFS characterizations indicate that the Ni-N₃ promotes CO₂ activation and Cr-N₂ accelerates H₂O dissociation. Theoretical investigations unveil the thermodynamic and kinetic superiorities of dual-active-site mechanism. Ni-N₃/Cr-N₂ exhibits higher FE_CO than Ni-N₃, whereas Cr-N₄ displays a strong preference for HER. The zero-gap MEA attains J of up to −1000 mA cm⁻² with a FE_CO exceeding 85% at a cell voltage of −4.0 V, and maintains stable operation for over 100 h at a J of −200 mA cm⁻².

Organofunctional silanes are highly useful reagents in material science, functioning as effective crosslinking agents and adhesion promoters. Traditionally, their synthesis relies on precious transition-metal catalysts, which require downstream purification and increase overall costs. Herein, we present a green and sustainable biocatalytic platform for the enantioselective synthesis of diverse organofunctional silanes bearing ester and cyano groups. Directed evolution of Thermus amyloliquefaciens protoglobin (TamPgb) produced efficient enzymes for cyclopropanation of vinyl silanes and siloxanes using diazo compounds and N-tosylhydrazones as carbene precursors with excellent diastereo- and enantiocontrol (up to 2500 TTN, >99% dr, >99% ee). Notably, we demonstrate for the first time that N-tosylhydrazones can serve as carbene precursors in enzymatic reactions, providing a safer and more practical alternative for industrial applications.

The catalytic dearomative dicarbofunctionalization of indoles constitutes one of the most efficient ways to access poly-substituted indolines that are prevalent in many natural products and drugs. However, despite significant advances, three component dearomative dicarbofunctionalization of indoles has remained elusive. Herein, we report an unprecedented nickel-catalyzed dearomative dialkylation of indoles with two different alkyl halides via three component cross-electrophile coupling under mild conditions with the construction of two vicinal C(sp³)─C(sp³) bonds at C2 and C3 sites. The catalytic protocol offers an efficient and straightforward route for the modular assembly of diverse carbon quaternary center-containing dialkylated indoline derivatives with a broad substrate scope (75 examples), excellent functional group tolerance and high chemo- and diastereoselectivities. Mechanistic studies, combining a series of experiments and DFT calculations, reveal that the catalytic reaction proceeds via a radical pathway.

Micelle-confined synthesis is a well-established bottom-up strategy for nanomaterials synthesis, offering precise synthetic control and inherent dispersibility in solution. Herein, we pioneer a reverse micelle-confined growth strategy for synthesizing two-dimensional conjugated metal-organic frameworks (2D c-MOFs) colloids, including Cu/Zn/Mn-HHTP. And scalable synthesis under mild conditions is also achieved. The confined space of micelle microenvironment effectively regulates the growth kinetics and stacking morphology, yielding nanoscale 2D c-MOFs in minutes that form stable colloids in various solvents for over 20 days. Considering the efficient visible-near infrared absorption in addition to the strong light-matter interactions of the 2D c-MOF colloids, an exceptional photothermal conversion efficiency of 80.3% is achieved under 880 nm laser irradiation, which outperforms most other 2D photothermal materials. Leveraging this, the material served as an efficient catalyst toward the selective oxidation of a chemical warfare agent simulant (i.e., 2-chloroethyl ethyl sulfide, CEES) under visible light, reaching near 100% yield to non-toxic sulfoxide with extremely low 2D c-MOFs usage. Our work highlights that micelle-confined synthesis serves as an efficient, energy-saving, and green strategy for fabricating 2D c-MOF colloids, paving the way for their applications in catalysis and beyond.

Konjugierte Nanoreifen haben aufgrund ihrer einzigartigen Konjugation sowie ihrer strukturellen, optoelektronischen und morphologischen Eigenschaften an hoher Relevanz gewonnen. Neuere synthetische Fortschritte haben den Zugang zu komplexeren Strukturen ermöglicht, bei denen zwei konjugierte Nanoreifen über eine zentrale Verknüpfungseinheit kovalent verbunden sind, sogenannte Doppelnanoreifen. Doppelnanoreifen erweitern die molekulare Vielfalt gespannter Nanokohlenstoffe und können Eigenschaften aufweisen, die die monomerer Nanoreifen übertreffen. Sie sind häufig intrinsisch chiral und stellen vielversprechende Kandidaten als chiral-polarisiertes Licht emittierende Materialien dar; zudem sind sie mit ihren zwei Kavitäten interessante supramolekulare Wirte. In dieser Übersicht fassen wir die bislang berichteten Doppelnanoreifen zusammen, deren Schlaufen ausschließlich aus Oligoparaphenylen-Einheiten bestehen. Wir klassifizieren ihre Strukturen in phenylenverknüpfte Doppelnanoreifen, Doppelnanoreifen mit X-förmigen Verknüpfungseinheiten, Zickzack-Doppelnanoreifen, lemniskatenförmige Doppelnanoreifen und sonstige Doppelnanoreifen. Darüber hinaus identifizieren wir vier Hauptsyntheserouten, die üblicherweise verwendet werden und auf gewinkelten Oligoparaphenylen-Vorstufen basieren. Die Eigenschaften sowie Anwendungen der einzelnen Doppelnanoreifen werden jeweils diskutiert. Diese Übersicht zeigt, dass Kreativität und synthetische Ausdauer zu einzigartigen Doppelnanoreifen mit attraktiven chiroptischen und supramolekularen Eigenschaften führen können.

Precise control over the photocatalytic selectivity by single atoms is ubiquitous in natural systems but remains a formidable challenge for artificial photocatalysts. Here, we present a series of porphyrin-based metallacages with nearly identical architectures that differ only in the central metal atoms (Co, Ni, Cu, and Zn) of the porphyrin ligands. The distinct d-orbital electron distribution of these metal centers governs ligand-to-metal charge transfer, resulting in divergent reactive oxygen species (ROS) generation pathways. The Co–porphyrin cage promotes electron transfer to produce superoxide anion (O₂^•−), whereas the Zn–porphyrin cage favors energy transfer to generate singlet oxygen (¹O₂); Ni- and Cu-porphyrin cages exhibit dual behavior. These variations lead to distinct oxidation selectivity of α-terpinene, yielding either p-cymene (via O₂^•−) or ascaridole (via ¹O₂). Moreover, secondary coordination between the porphyrin metals and poly(4-vinylpyridine) affords robust supramolecular networks for heterogeneous catalysis with enhanced stability and recyclability. This study establishes single-atom modulation within metallacage frameworks as an effective strategy to control ROS generation and photocatalytic selectivity, paving the way toward the practical applications of metallacage-based photocatalytic systems.