Meta Junction Promoting Efficient Thermally Activated Delayed Fluorescence in Donor-Acceptor Conjugated Polymers

The meta junction is proposed to realize efficient thermally activated delayed fluorescence (TADF) in donor–acceptor (D-A) conjugated polymers. Based on triphenylamine as D and dicyanobenzene as A, as a proof of concept, a series of D-A conjugated polymers has been developed by changing their connection sites. When the junction between D and A is tuned from para to meta, the singlet–triplet energy splitting (ΔE_ST) is found to be significantly decreased from 0.44 to 0.10 eV because of the increasing hole–electron separation. Unlike the para-linked analogue with no TADF, consequently, the meta-linked polymer shows a strong delayed fluorescence. Its corresponding solution-processed organic light-emitting diodes (OLEDs) achieve a promising external quantum efficiency (EQE) of 15.4 % (51.9 cd A⁻¹, 50.9 lm W⁻¹) and CIE coordinates of (0.34, 0.57). The results highlight the bright future of D-A conjugated polymers used for TADF OLEDs.     

Reactivity and Lability Modulated by a Valence Electron Moving in and out of 25-Atom Gold Nanoclusters

The emergence of atomically precise metal nanoclusters with unique electronic structures provides access to currently inaccessible catalytic challenges at the single-electron level. We investigate the catalytic behavior of gold Au₂₅(SR)₁₈ nanoclusters by monitoring an incoming and outgoing free valence electron of Au 6s¹. Distinct performances are revealed: Au₂₅(SR)₁₈⁻ is generated upon donation of an electron to neutral Au₂₅(SR)₁₈⁰ and this is associated with a loss in reactivity, whereas Au₂₅(SR)₁₈⁺ is generated from dislodgment of an electron from neutral Au₂₅(SR)₁₈⁰ with a loss in stability. The reactivity diversity of the three Au₂₅(SR)₁₈ clusters stems from different affinities with reactants and the extent of intramolecular charge migration during the reactions, which are closely associated with the valence occupancies of the clusters varied by one electron. The stability difference in the three clusters is attributed to their different equilibria, which are established between the AuSR dissociation and polymerization influenced by one electron.     

Spatially Responsive Multicolor Lanthanide-MOF Heterostructures for Covert Photonic Barcodes

Micro/nanoscale photonic barcodes based on multicolor luminescent segmented heterojunctions hold potential for applications in information security. However, such multicolor heterojunctions reported thus far are exclusively based on static luminescent signals, thus restricting their application in advanced confidential information protection. Reported here is a strategy to design responsive photonic barcodes with heterobimetallic (Tb³⁺/Eu³⁺) metal—organic framework multicolor heterostructures. The spatial colors could be precisely controlled by thermally manipulating the energy-transfer process between the two lanthanides, thus achieving responsive covert photonic barcodes. Also demonstrated is that spatially resolved responsive barcodes with multi-responsive features could be created in a single heterostructure. These findings offer unique opportunities to purposely design highly integrated responsive microstructures and smart devices toward advanced anti-counterfeiting applications.     

Engineering the Charge-Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Spiro conjugation has been proposed to dictate the efficiency of charge transfer, which could directly affect the spin–orbit charge transfer intersystem crossing (SOCT-ISC) process. However, this process has yet to be exemplified. Herein, we prepared three spirobis[anthracene]diones, in which two benzophenone moieties are locked in close proximity and differentially functionalized to fine-tune the charge transfer state. Its feasibility for SOCT-ISC was theoretically predicted, then experimentally evaluated. Through fine-tuning the spiro conjugation coupling and varying the solvent dielectric constants, ISC rate constants were engineered to vary in a dynamic range of three orders of magnitude, from 7.8×10⁸ s⁻¹ to 1.0×10¹¹ s⁻¹, which is the highest ISC rate reported for SOCT-ISC system to our knowledge. Our findings substantiate the key factors for effective SOCT-ISC and offer a new avenue for the rational design of heavy atom free triplet sensitizers.     

Impact of titanate coupling agent on properties of high density polyethylene composite filled with coal gangue

In this study, surface modification of coal gangue (CG) was performed with titanate coupling agent 201 (isopropyl tri(dioctylpyrophosphate) titanate), and the effects of surface modifier on mechanical properties and thermal stability of high-density polyethylene filled with CG (HDPE/CG) and high-density polyethylene filled with modified CG (HDPE/mCG) composites were investigated. The coupling agent was successfully grafted on CG surface through chemical reaction according to the analyses of Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the coupling agent can effectively enhance the hydrophobicity of surface that was verified by water contact angle beyond 90° of modified CG sample. With the introduction of coupling agent, some enhancements of tensile strength, flexural strength, and impact strength were observed in HDPE/mCG compared with HDPE/CG, due to the improved compatibility between mCG fillers and matrix. The increased storage modulus and decreased loss factor of HDPE/mCG composite further confirm the stronger interface adhesion after modification. Moreover, it is found that titanate coupling agent 201 can improve the thermal stability of HDPE/mCG composite to some extent.     

可拉伸超韧水凝胶的制备和应用

综述了可拉伸超韧水凝胶的设计原理及其在组织工程和柔性电子器件领域的应用. 通过将网络结构层次、 化学结构、 增韧机制与宏观力学性能相结合, 重点讨论了单网络水凝胶、 双网络水凝胶、 纳米复合水凝胶及其它水凝胶等可拉伸超韧水凝胶的研究进展, 并总结和展望了新思路和新方向.     

深共融溶剂中合成2,4-二取代喹啉衍生物

在氯化胆碱和氯化锌组成的深共融溶剂中,以2-氨基苯乙酮和芳香炔烃为原料,通过环化偶联反应,合成了一系列2,4-二取代喹啉衍生物;当n(氯化胆碱)∶n(氯化锌)=1∶2,反应温度为80℃时,反应3 h即获得高达98%的产率.该方法无需额外添加催化剂,而且反应条件温和、操作简单、底物范围较广泛.     

The miracle role of lattice imperfections in benzene alkylation with methanol over mordenite

Mordenite (MOR) has demonstrated potential as a catalyst for alkylation due to high variability, intrinsic porosity, and outstanding stability. However, the contact probability of benzene and methanol has been limited by typical layered structures of MOR and there is no connection between layers. Here, we report the preparedness of H-MOR via a sequential post-treatment method based on a commercial MOR. H-MOR sample had appeared lattice imperfections inferred from characterization means. The samples were tested with benezene methylation reaction. Results show that the high conversion of benzene and the high selectivity of toluene were obtained from the miracle role of lattice imperfections in the H-MOR sample. Sequentially, based on the study of all catalyst structure and physical properties, a plausible reaction mechanism for the selectivity of the desired toluene was proposed.     

Metal-reinforced sulfonic-acid-modified zirconia for the removal of trace olefins from aromatics

Metal-reinforced sulfonic-acid-modified zirconia catalysts were successfully prepared and used to remove trace olefins from aromatics in a fixed-bed reactor. Catalysts were characterized by ICP-OES, N₂ adsorption–desorption, X-ray diffraction, thermogravimetric analysis (TGA), and pyridine-FTIR spectroscopy. Different metals and calcination temperatures had great influence on the catalytic activity. Alumina-reinforced sulfated zirconia exhibited outstanding catalytic performance, stable regeneration activity, and giant surface area, and are promising in industrial catalysis. TGA showed that the decomposition of methyl could be attributed to Brønsted acid sites, and pyridine-FTIR spectroscopy proved the weak Brønsted sites on these synthesized metal-reinforced sulfated zirconia. Also, a relation between the reaction rate and weak Brønsted acid density is proposed.     

Solvo-thermal Preparation and Characterization of Two CdII Coordination Polymers Constructed From 2,6-(1,2,4-Triazole-4-yl)pyridine and 5-R-Isophthalic Acid (R = Nitro,Sulfo)

Under the solvo-thermal conditions, two novel Cd^II mixed-ligand coordination materials with 2,6-(1,2,4-triazole-4-yl)pyridine(L₁) and aromatic poly-carboxylic acid co-ligands such as 5-R-isophthalic acid (R = nitro, sulfo), namely [Cd(L₁)(NO₂-BDC)(H₂O)₂] · 2H₂O ( 1 ) and [Cd(L₁)(HSIP)(H₂O)] · 4H₂O ( 2 ) (NO₂-H₂BDC = 5-nitroisophthalic acid, H₃SIP = 5-sulfobenzene -isophthalic acid) were successfully prepared. These Cd^II mixed-ligand coordination polymers 1 – 2 have been measured by crystal X-ray analysis, FT-IR spectra and powder X-ray diffraction analyses. In 1 , these seven-coordinate Cd^II atoms (Cd1) are inter-linked by didentate 5-nitroisophthalic acid ligands forming 1D chain structures. In 2 , these L₁ and partially de-pronated HSIP^2– are inter-linked by central Cd^II centers and are arranged into the unique 2D micro-porous metal-organic framework of 2 . Side view of 2 , it is noted that numerous oxygen atoms of un-coordinated carboxylate groups and coordinated SO₃ groups protrude out and decorate the 2D framework of 2 . PXRD patterns of 1 and 2 sample is tested, which is consistent with the simulated PXRD diffraction pattern. Photoluminescence studies show that 2 is highly selective and sensitive to trace elements of Eu³⁺ with excellent K_sv value (7.86 × 10⁴ m ^–1) and low detection limit (5.56 × 10^–2 mM), which also provides a convenient method and platform for real-time detection of Eu³⁺.