CCS Chemistry最新文献

Understanding the process of chemical reactions has always been a relentless pursuit for chemists. The development of femtosecond pump-probe techniques since the 1980s has revolutionized the field of chemical dynamics, enabling the capture of time-resolved snapshots of reactions on the femtosecond timescale. Starting from the 2010s, breakthroughs in femtosecond electron and X-ray sources has enabled ultrafast electron and X-ray diffraction techniques, which is able to directly reveal the temporal evolution of atomic geometries of molecules, allowing for the creation of molecular movies. Gas-phase molecular movies reveal intrinsic intramolecular processes, while liquid-phase molecular movies provide insights for complicated solvent-solute interplay. This mini-review focuses on the advances in studying gas-phase and liquid-phase molecular dynamics (MD) using ultrafast electron and X-ray diffraction techniques on femtosecond and picosecond timescales. The fast-developing experimental capability of the direct observation of molecular structural evolution during chemical reactions, on its natural femtosecond timescale and subangstrom length scale, offers tremendous potential for the field of chemical kinetics and MD.

Organic scintillators that efficiently generate bright triplet excitons are of critical importance for high-performance X-ray-excited luminescence in radiation detection. However, the nature of triplet-singlet spin-forbidden transitions in these materials often result in long-lived phosphorescence, which is undesirable for ultrafast X-ray detection and imaging. Here we demonstrate that the effect of hybridized local and charge-transfer (HLCT) excited states enables organic scintillators to exhibit highly efficient and fast radioluminescence (RL) in response to X-ray irradiation. Our experimental and theoretical investigation shows that the oxidized 1,8-naphthalimide-phenothiazine dyad (OMNI-PTZ 2) with HLCT-excited states has an enhanced overlap integral of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) on MNI π-orbitals, and moderate donor–acceptor electron interactions. As a result, the RL of these crystals exhibits a 61-fold increase and its monoexponential decay lifetime is three orders of magnitude faster compared to its corresponding thermally activated delayed fluorescence (TADF) molecule MNI-PTZ 1. We further demonstrate the practical utility of the OMNI-PTZ 2 (G) in high-performance X-ray detection and imaging, achieving an X-ray dose sensitivity of 97 nGy s⁻¹ and an exceptional spatial resolution of 20 lp/mm. Our study provides a promising molecular design principle for utilizing triplet excitons to develop high-efficiency and fast X-ray scintillators for the development of next-generation flexible and stretchable X-ray imaging detectors.

Dual-atom catalysts (DACs) represent an exciting advance in the field of heterogeneous catalysis. They not only retain the beneficial characteristics of single-atom catalysts (SACs), but they also harness the synergistic effects that arise from the proximity of neighboring single-metal atoms. Nevertheless, the fabrication of heteronuclear dual-atom metals positioned adjacently for use in photocatalysis remains a significant challenge. Herein, we report the atomically dispersed adjacent Pt–Ag dual-atom pairs on carbon nitride (Pt₁Ag₁-a/CN) by a facile hydrogen-bonding assembly strategy via pyrolysis of the hydrogen-bonding supramolecule containing melamine-Ag and cyanuric acid-Pt complexes on carbon nitride (CN), through which the light absorption depressed by deposited carbonaceous materials during the preparation of dual-atom metals via a traditional method like the pyrolysis of the metal–organic framework. Thanks to the synergism achieved by the bonding interaction of adjacent Pt and Ag single-atom pairs, the developed Pt₁Ag₁-a/CN with 0.21% Pt loading shows a high turnover frequency (TOF) of 1115 h⁻¹ with a H₂ evolution rate (HER) of 12,000 µmol g⁻¹ h⁻¹ for photocatalytic water splitting under simulated solar light irradiation (325 h⁻¹ of TOF with 3480 µmol g⁻¹ h⁻¹ of HER under visible light irradiation). This strategy outperforms the previously reported SACs on CN-based semiconductors. Density functional theory (DFT) calculations demonstrate that the adjacent Ag atom acts as a coordination atom to effectively regulate the electronic structure of the Pt atom and thus brings the d-band center of Pt close to the Fermi energy level, which is beneficial for the H₂ production. This work presents a facile and general strategy for designing diverse adjacent diatomic cocatalysts in photocatalysis without depressing light absorption by the deposited carbon during the DAC preparation via previously reported methods.

In this work, novel D–A alternating polymers (PJ-1, PJ-2, and PJ-3) with chlorinated benzodithiophene and chlorinated thiazole units were synthesized via gradual chlorination. These polymers could be obtained readily through a few concise synthesis steps. Among them, PJ-1 displayed desirable properties including energy levels, crystallinity, and charge transport capabilities. The binary and ternary organic solar cells (OSCs) fabricated based on PJ-1 displayed significant power conversion efficiency (PCE) of 15.02% and 19.12%, respectively, placing them among the highest reported for ternary OSCs. Notably, the PJ1-based devices also showcased one of the highest figure-of-merit values, indicating their promising potential for future applications. This study offers valuable insights and supports the development of cost-effective and high-performance polymer donors for the generation of OSCs.

Selective reduction of readily available N-heteroarenes is important in both organic synthesis and chemical biology. Herein, we describe ligand-controlled regiodivergent hydroboration of quinolines using well-defined amido–manganese catalysts, with an emphasis on the rarely reported 1,4-regioselectivity. Mechanistic studies showed that 1,2-hydroboration of quinoline was kinetically favorable and reversible, whereas 1,4-hydroboration was under thermodynamic control. Using a 1-methyimidazole-based pincer amido–manganese complex as the catalyst, cooperative C–H···N and π···π noncovalent interactions between the 1-methyimidazole moiety and quinoline substrates enabled kinetic accessibility of 1,4-hydroboration, giving thermodynamically favored 1,4-hydroborated quinolines as the major products. On this basis, Mn-catalyzed 1,4-hydroboration of a series of substituted quinolines proceeded smoothly in high yields. A high turnover number of 2500 was achieved in this reaction with satisfying regioselectivity. This transformation could be further applied to the C3-selective functionalization of quinolines, highlighting the synthetic utility of this methodology. In contrast, using a pyridine-based pincer amido–manganese complex as the catalyst, which lacked the C–H···N interaction, the free-energy barrier for 1,4-hydroboration significantly increased through a N–B···N interaction between the “HMn–NB” species and quinoline, resulting in the kinetically favored 1,2-hydroboration product with excellent regioselectivity.

Reducing the emission of agrochemicals hazardous to the environment and human health is one of the key targets of the UN’s Sustainable Development Goal 12. Herein, we report a kind of quaternary ammonium pesticides with an acid-cleavable silaketal linkage on their backbones that enables control of hydrolysis. These pesticides possess outstanding bactericidal and insecticidal properties but become harmless to humans and other organisms after hydrolysis. Depending on the conditions of use, the hydrolytic process can be controlled over the time range of 10 min to 3 months. Both laboratory simulations and agricultural field demonstrations confirm that these pesticides can effectively protect crops from bacterial diseases and pests. At the sametime, single-dose intragastric administration using diisopropylsilyloxy bisquaternary ammonium salt 9 (ISBQAS-9) in mice demonstrates its safety for multiple organs. Owing to the advantages of controllable degradability, environmental friendliness, and the low financial cost of these pesticides, this well-designed strategy holds great promise for the generation of environmentally harmless pesticides and the development of green agriculture.

Polarity is a critical microenvironmental factor of the plasma membrane, which can offer valuable insights into various biological processes. Herein, we proposed a novel strategy for the construction of fluorescent agents to measure plasma membrane polarity by conjoining twisted intramolecular charge transfer (TICT) modulation and charge number control. It is shown that compounds with a stronger TICT tendency are more sensitive to polarity shifts due to the number of dialkylated amino groups present (from 1 to 3), and the molecules with two or more charged centers remain in the plasma membrane. Therefore, we developed two fluorescent agents with high polarity sensitivity, excellent turn-on ratios, and superior ability, to target the plasma membrane. In the wash-free fluorescence imaging and fluorescence lifetime tests, our designed agent could detect plasma membrane polarity with high precision, allowing effective distinction between cancer cells and normal cells based on their differences in plasma membrane polarity. Moreover, both fluorescence and fluorescence lifetime changes of the plasma membrane in the ferroptosis model established by Sorafenib confirmed an increase in plasma membrane polarity during cell ferroptosis.