Tunable Gas‐Gas Reactions through Nanobubble Pathway

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Tunable Gas-Gas Reactions through Nanobubble Pathway

The feasibility of gas-gas reaction between H2 and O2 bulk nanobubbles is demonstrated, which deepens the understanding on the non-combustion gas-gas reaction mechanism in nanoscale space. It also provides new pathways for green energy conversion and synthesis of many intermediate and final products, which are inaccessible under mild conditions.


Abstract

Combustible gas-gas reactions usually do not occur spontaneously upon mixing without ignition or other triggers to lower the activation energy barrier. Nanobubbles, however, could provide such a possibility in solution under ambient conditions due to high inner pressure and catalytic radicals within their boundary layers. Herein, a tunable gas-gas reaction strategy via bulk nanobubble pathway is developed by tuning the interface charge of one type of bulk nanobubble and promoting its fusion and reaction with another, where the reaction-accompanied size and number concentration change of the bulk nanobubbles and the corresponding thermal effect clearly confirm the occurrence of the nanobubble-based H2/O2 combustion. In addition, abundant radicals can be detected during the reaction, which is considered to be critical to ignite the gas reaction during the fusion of nanobubbles in water at room temperature. Therefore, the nanobubble-based gas-gas reactions provide a safe and efficient pathway to produce energy and synthesize new matter inaccessible under mild or ambient conditions.

Synthetic control of thorium metal–organic frameworks for sequencing and sensing of radioiodine species

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Comprehensive Summary

Exploring the physiochemical properties and expanding the applications of actinide-containing materials is paramount to address the escalating challenge of radioactive waste accumulation. However, unlocking the full potential of these materials is largely crippled by the radiotoxicity of the actinides. We report here two porous and luminescent thorium-based metal-organic frameworks (Th-BITD-1 and Th-BITD-2) that serve as a bifunctional platform for sequencing and sensing of radioiodine, a much more radioactive fission product discharged during the nuclear fuel reprocessing. In particular, the resulting Th-BITD-1 displays better iodine uptake performance than Th-BITD-2 via the solution-based process and vapor diffusion with the maximum adsorption capacities of 831 and 1099 mg/g, respectively. Furthermore, Th-BITD-1 can function as a highly sensitive luminescence sensor for iodate with a quenching constant (KSV) of 6.6(5)×103 M−1 and a detection limit of 2.02 μM, respectively, outperforming 2.96(6) ×103 M−1 and 10.5 μM of Th-BITD-2. Moreover, a positive correlation between the sensing efficacy and the iodate adsorption capacity has been revealed. This work highlights the opportunity in designing novel actinide-based MOFs for their potential applications in radiological fields, e.g., radionuclide separation and detection.

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Nickel‐Catalyzed Regioselective Hydrosilylation of Conjugated Dienes

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Comprehensive Summary

With the increasing demand for homoallylic silanes and allylic silanes, the highly efficient and regioselective hydrosilylations of conjugated dienes are urgently needed. Herein, we developed a Ni-catalyzed regiodivergent hydrosilylation of aromatic conjugated dienes by adjusting the temperature and ligands. Under low temperature (-30 oC), an eternal-ligand-free system (Ni/t-BuOK) can efficiently facilitate the 3,4-anti-Markovnikov hydrosilylation to provide homoallylic silanes via electrophilic activation process; under room temperature (25 oC), a ligand-controlled system (Ni/t-BuOK/PPh3) can eventuate the 3,4-Markovnikov hydrosilylation to produce allylic silanes via Chalk-Harrod process. Both systems are compatible with various conjugated dienes and primary silanes in excellent yields and regioselectivities.

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Application of Ion Mobility Spectrometry–Mass Spectrometry for Compositional Characterization and Fingerprinting of a Library of Diverse Crude Oil Samples

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Abstract

Exposure characterization of crude oils, especially in time-sensitive circumstances such as spills and disasters, is a well-known analytical chemistry challenge. Gas chromatography–mass spectrometry is commonly used for “fingerprinting” and origin tracing in oil spills; however, this method is both time-consuming and lacks the resolving power to separate co-eluting compounds. Recent advances in methodologies to analyze petroleum substances using high-resolution analytical techniques have demonstrated both improved resolving power and higher throughput. One such method, ion mobility spectrometry–mass spectrometry (IMS–MS), is especially promising because it is both rapid and high-throughput, with the ability to discern among highly homologous hydrocarbon molecules. Previous applications of IMS–MS to crude oil analyses included a limited number of samples and did not provide detailed characterization of chemical constituents. We analyzed a diverse library of 195 crude oil samples using IMS–MS and applied a computational workflow to assign molecular formulas to individual features. The oils were from 12 groups based on geographical and geological origins: non-US (1 group), US onshore (3), and US Gulf of Mexico offshore (8). We hypothesized that information acquired through IMS–MS data would provide a more confident grouping and yield additional fingerprint information. Chemical composition data from IMS–MS was used for unsupervised hierarchical clustering, as well as machine learning–based supervised analysis to predict geographic and source rock categories for each sample; the latter also yielded several novel prospective biomarkers for fingerprinting of crude oils. We found that IMS–MS data have complementary advantages for fingerprinting and characterization of diverse crude oils and that proposed polycyclic aromatic hydrocarbon biomarkers can be used for rapid exposure characterization. Environ Toxicol Chem 2023;00:1–14. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

CsPbBr3 Perovskite Nanocrystals for Photocatalytic [3+2] Cycloaddition

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Visible-light-induced halide-exchange between halide perovskite and organohalide solvents has been studied in which photo-induced electron-transfer from CsPbBr3 nanocrystals (NCs) to dihalomethane solvent molecules produces halide anions via reductive dissociation, followed by a spontaneous anion-exchange. Photo-generated holes in this process are less focused. Here, for CsPbBr3 in dibromomethane (DBM), we discover that Br radical (Br•) is a key intermediate resulting from the hole-oxidation. We successfully trapped Br• with reported methods and found that Br• is in continuous generation in DBM under visible light irradiation, hence imperative for catalytic reaction design. Continuous Br• within this halide-exchange process is active for photocatalytic [3+2] cycloaddition for vinylcyclopentane synthesis, a privileged scaffold in medicinal chemistry, with good yield and rationalized diastereoselectivity. The NCs photocatalyst is highly recyclable due to Br-based self-healing, leading to a particularly economic and neat heterogeneous reaction where the solvent DBM also behaves as a co-catalyst for perovskite photocatalysis. Halide perovskites, notable for efficient solar energy conversion, herein are demonstrated as an exceptional photocatalyst for Br radical-mediated [3+2] cycloaddition. We envisage such perovskite-induced Br radical strategy may serve as a powerful chemical tool to develop valuable halogen radical-involved reactions.

Catalyst‐Free Regioselective C3­­­‐H Benzoxylation of 1H‐Indoles with Benzoyl Peroxide

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An efficient catalyst-free C-O bond formation reaction for the synthesis of 1H-indol-3-yl benzoates was developed through C(sp2)-H functionalization of 1H indoles with benzoyl peroxide (BPO) in acetonitrile at room temperature under open flask conditions. The reaction proceeds without exclusion of air or moisture and is applied to a wide array of electronically differentiated indoles as well as BPOs. C-3 benzoxylation of indoles was achieved with excellent regioselectivity under mild and easy to operate conditions. The reaction is scalable to one gram level.

Chemical Tailoring Assisted non‐TADF to TADF Switching in Carbazole‐Benzophenone Emitter ‐ An In‐silico Investigation

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Organic light-emitting diodes (OLEDs) have become one of the most popular lighting technologies since they offer several advantages over conventional devices. In carbazole-benzophenone (CzBP) OLED devices, the polymeric form of the compound is previously reported to be Thermally Activated Delayed Fluorescence (TADF)-active (∆EST ≈ 0.12 eV), while the monomer (CzBP) (∆EST ≈ 0.39 eV) does not. The present study examines the effects of chemical tailoring on the optical and photophysical properties of CzBP using DFT and TDDFT methods. The introduction of a single – NO2 group or di-substitution ( – NO2 , – COOH or – CN) in the selected LUMO region of the reference CzBP monomer significantly reduces ∆EST ≈ 0.01 eV, projecting these systems as potential TADF-active emitters. Furthermore, the chemical modification of CzBP-LUMO alters the two-step TADF mechanism (T1 → T2 → S1 ) in CzBP (ES1 > ET2 > ET1 ) to the Direct Single Harvest (T1 → S1 ) mechanism (ET2 > ES1 > ET1 ), which has recently been identified in the fourth-generation OLED materials.