Frenkel Defect-modulated Anti-thermal Quenching Luminescence in Lanthanide-doped Sc2(WO4)3

Although large amount of effort has been invested in combating thermal quenching that severely degrades the performance of luminescent materials particularly at high temperatures, not much affirmative progress has been realized. Herein, we demonstrate that the Frenkel defect formed via controlled annealing of Sc₂(WO₄)₃:Ln (Ln=Yb, Er, Eu, Tb, Sm), can work as energy reservoir and back-transfer the stored excitation energy to Ln³⁺ upon heating. Therefore, except routine anti-thermal quenching, thermally enhanced 415-fold downshifting and 405-fold upconversion luminescence are even obtained in Sc₂(WO₄)₃:Yb/Er, which has set a record of both the Yb³⁺-Er³⁺ energy transfer efficiency (>85 %) and the working temperature at 500 and 1073 K, respectively. Moreover, this design strategy is extendable to other hosts possessing Frenkel defect, and modulation of which directly determines whether enhanced or decreased luminescence can be obtained. This discovery has paved new avenues to reliable generation of high-temperature luminescence.     

Multi-Resonance Building-Block-Based Electroluminescent Material: Lengthening Emission Maximum and Shortening Delayed Fluorescence Lifetime

Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials are considered a class of organic materials with exceptional electronic and optical properties, which make them promising for the applications in organic light-emitting diodes (OLEDs). In this study, we improved, synthesized, and characterized a multiple-resonance type emitter based on the assembly of MR-building blocks (MR-BBs). By optimizing the geometric arrangement of MR-BBs, we were able to generate narrowband emission in the longer wavelength region and shorten the delayed excited-state lifetime, resulting in improved emission efficiency compared to the parent molecule. Our proof-of-concept molecule, m-DBCz, exhibited narrowband yellowish-green TADF emission with a full width at half-maximum of 32 nm and a small singlet-triplet energy gap of 0.04 eV. The OLED developed using m-DBCz as the emitter demonstrated electroluminescence at 548 nm and achieved a high external quantum efficiency (EQE) of 34.9 %. Further optimization of the device resulted in a high external quantum efficiency of 36.3 % and extremely low efficiency roll-off, with EQE values of 30.1 % and 27.7 % obtained even at high luminance levels of 50 000 and 100 000 cd m⁻². These results demonstrate the full potential of MR-TADF materials for applications on ultrahigh-luminance OLEDs.     

Insights into Anion-Solvent Interactions to Boost Stable Operation of Ether-Based Electrolytes in Pure-SiOx||LiNi0.8Mn0.1Co0.1O2 Full Cells

Ether solvents with superior reductive stability promise excellent interphasial stability with high-capacity anodes while the limited oxidative resistance hinders their high-voltage operation. Extending the intrinsic electrochemical stability of ether-based electrolytes to construct stable-cycling high-energy-density lithium-ion batteries is challenging but rewarding. Herein, the anion-solvent interactions were concerned as the key point to optimize the anodic stability of the ether-based electrolytes and an optimized interphase was realized on both pure-SiO_x anodes and LiNi_0.8Mn_0.1Co_0.1O₂ cathodes. Specifically, the small-anion-size LiNO₃ and tetrahydrofuran with high dipole moment to dielectric constant ratio realized strengthened anion-solvent interactions, which enhance the oxidative stability of the electrolyte. The designed ether-based electrolyte enabled a stable cycling performance over 500 cycles in pure-SiO_x||LiNi_0.8Mn_0.1Co_0.1O₂ full cell, demonstrating its superior practical prospects. This work provides new insight into the design of new electrolytes for emerging high-energy density lithium-ion batteries through the regulation of interactions between species in electrolytes.     

Instantaneous Free Radical Scavenging by CeO2 Nanoparticles Adjacent to the Fe−N4 Active Sites for Durable Fuel Cells

To achieve the Fe−N−C materials with both high activity and durability in proton exchange membrane fuel cells, the attack of free radicals on Fe−N₄ sites must be overcome. Herein, we report a strategy to effectively eliminate radicals at the source to mitigate the degradation by anchoring CeO₂ nanoparticles as radicals scavengers adjacent (Sca^ad-CeO2) to the Fe−N₄ sites. Radicals such as ⋅OH and HO₂⋅ that form at Fe−N₄ sites can be instantaneously eliminated by adjacent CeO₂, which shortens the survival time of radicals and the regional space of their damage. As a result, the CeO₂ scavengers in Fe−NC/Sca^ad-CeO2 achieved ∼80 % elimination of the radicals generated at the Fe−N₄ sites. A fuel cell prepared with the Fe−NC/Sca^ad-CeO2 showed a smaller peak power density decay after 30,000 cycles determined with US DOE PGM-relevant AST, increasing the decay of Fe−NC_Phen from 69 % to 28 % decay.     

Enantioselective Synthesis of Biscyclopropanes Using Alkynes as Dicarbene Equivalents

Chiral biscyclopropanes are an important skeleton in many bioactive molecules. However, there are few routes to synthesize these molecules with high stereoselectivity due to the nature of multiple stereocenters. Herein, we report the first example of Rh₂(II)-catalyzed enantioselective synthesis of bicyclopropanes with alkynes as dicarbene equivalents. The bicyclopropanes with 4–5 vicinal stereocenters and 2–3 all-carbon quaternary centers were constructed in excellent stereoselectivity. This protocol features high efficiency and excellent functional group tolerance. Moreover, the protocol was also extended to the cascaded cyclopropanation/cyclopropenation with excellent stereoselectivities. In these processes, both sp-carbons of alkyne were converted into stereogenic sp³-carbons. Experimental and density functional theory (DFT) calculations revealed that the cooperative weak hydrogen bonds between the substrates and the dirhodium catalyst may play key roles in this reaction.     

Dibenzothiophene Sulfone-Based Ambipolar-Transporting Blue-Emissive Organic Semiconductors Towards Simple-Structured Organic Light-Emitting Transistors

The development of blue-emissive ambipolar organic semiconductor is an arduous target due to the large energy gap, but is an indispensable part for electroluminescent device, especially for the transformative display technology of simple-structured organic light-emitting transistor (SS-OLET). Herein, we designed and synthesized two new dibenzothiophene sulfone-based high mobility blue-emissive organic semiconductors (DNaDBSOs), which demonstrate superior optical property with solid-state photoluminescent quantum yield of 46–67 % and typical ambipolar-transporting properties in SS-OLETs with symmetric gold electrodes. Comprehensive experimental and theoretical characterizations reveal the natural of ambipolar property for such blue-emissive DNaDBSOs-based materials is ascribed to a synergistic effect on lowering LUMO level and reduced electron injection barrier induced by the interfacial dipoles effect on gold electrodes due to the incorporation of appropriate DBSO unit. Finally, efficient electroluminescence properties with high-quality blue emission (CIE (0.179, 0.119)) and a narrow full-width at half-maximum of 48 nm are achieved for DNaDBSO-based SS-OLET, showing good spatial control of the recombination zone in conducting channel. This work provides a new avenue for designing ambipolar emissive organic semiconductors by incorporating the synergistic effect of energy level regulation and molecular-metal interaction, which would advance the development of superior optoelectronic materials and their high-density integrated optoelectronic devices and circuits.     

Growing ZIF-8 Seeds on Charged COF Substrates toward Efficient Propylene-Propane Separation Membranes

We report a covalent organic framework (COF) induced seeding strategy to fabricate metal–organic framework (MOF) membranes. Contrary to graphene oxide nuclei-depositing substrate, COF substrate has uniform pore size, high microporosity and abundant functional groups. We designed a series of charged COF nanosheets to induce the formation of ZIF-8@COF nanosheet seeds with high aspect ratio over 150, which were readily processed into a compact and uniform seed layer. The resulting ZIF-8 membranes with thickness down to 100 nm exhibit an ultrahigh C₃H₆/C₃H₈ separation performance and superior long-term stability. Our strategy is also validated by fabricating ultrathin ZIF-67 and UiO-66 membranes.     

Neuroprotective Bioorthogonal Catalysis in Mitochondria Using Protein-Integrated Hydrogen-Bonded Organic Frameworks

Mitochondria-targeted bioorthogonal catalysis holds promise for controlling cell function precisely, yet achieving selective and efficient chemical reactions within organelles is challenging. In this study, we introduce a new strategy using protein-integrated hydrogen-bonded organic frameworks (HOFs) to enable synergistic bioorthogonal chemical catalysis and enzymatic catalysis within mitochondria. Utilizing catalytically active tris(4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium(II) to self-assemble with [1,1′-biphenyl]-4,4′-biscarboximidamide, we synthesized nanoscale RuB-HOFs that exhibit high photocatalytic reduction activity. Notably, RuB-HOFs efficiently enter cells and preferentially localize to mitochondria, where they facilitate bioorthogonal photoreduction reactions. Moreover, we show that RuB-HOFs encapsulating catalase can produce hydrogen sulfide (H₂S) in mitochondria through photocatalytic reduction of pro-H₂S and degrade hydrogen peroxide through enzymatic catalysis simultaneously, offering a significant neuroprotective effect against oxidative stress. Our findings not only introduce a versatile chemical toolset for mitochondria-targeted bioorthogonal catalysis for prodrug activation but also pave the way for potential therapeutic applications in treating diseases related to cellular oxidative stress.     

An Isolable Radical Anion Featuring a 2-Center-3-Electron π-Bond without a Clearly Defined σ-Bond

Featuring an extra electron in the π* antibonding orbital, species with a 2-center-3-electron (2c3e) π bond without an underlying σ bond are scarcely known. Herein, we report the synthesis, isolation and characterization of a radical anion salt [K(18-C-6)]⁺{[(HCNDipp)₂Si]₂P₂}⋅⁻ (i.e. [K(18-C-6)]⁺ 3 ⋅⁻) (18-C-6=18-crown-6, Dipp=2,6-diisopropylphenyl), in which 3 ⋅⁻ features a perfectly planar Si₂P₂ four-membered ring. This species represents the first example of a Si- and P-containing analog of a bicyclo[1.1.0]butane radical anion. The unusual bonding motif of 3 ⋅⁻ was thoroughly investigated via X-ray diffraction crystallography, electron paramagnetic resonance spectroscopy (EPR), and calculations by density functional theory (DFT), which collectively unveiled the existence of a 2c3e π bond between the bridgehead P atoms and no clearly defined supporting P−P σ bond.     

CycloSiFA: The Next Generation of Silicon-Based Fluoride Acceptors for Positron Emission Tomography (PET)

The ring-opening Si-fluorination of a variety of azasilole derivatives cyclo-1-(iPr₂Si)−4-X−C₆H₃−2-CH₂NR ( 4 : R=2,6-iPr₂C₆H₃, X=H; 4 a : R=2,4,6-Me₃C₆H₂, X=H; 9 : R=2,6-iPr₂C₆H₃, X=tBuMe₂SiO; 10 : R=2,6-iPr₂C₆H₃, X=OH; 13 : R=2,6-iPr₂C₆H₃, X=HCCCH₂O; 22 : R=2,6-iPr₂C₆H₃, X=tBuMe₂SiCH₂O) with different ¹⁹F-fluoride sources was studied, optimized and the experience gained was used in a translational approach to create a straightforward ¹⁸F-labelling protocol for the azasilole derivatives [¹⁸F] 6 and [¹⁸F] 14 . The latter constitutes a potential clickable CycloSiFA prosthetic group which might be used in PET tracer development using Cu-catalysed triazole formation. Based on our findings, CycloSiFA has the potential to become a new entry into non-canonical labelling methodologies for radioactive PET tracer development.