Science China Chemistry最新文献

By virtue of the atom- and step-economy, utilization of simple arenes as a supplant of pre-prepared aryl metal species or aryl halides for the synthesis of arylated chiral molecules has attracted great attention from the synthetic community. While transition-metal-catalyzed enantioselective diarylation of tethered alkenes has been employed to prepare important chiral cyclic compounds, the direct use of simple arenes as aryl precursors is still underdeveloped, probably due to the difficulties in the effective control of the reactivity, site-selectivity and/or enantioselectivity. Herein we report an asymmetric Pd/Ag dual metal catalytic system for the non-directed, site- and enantioselective domino Heck/intermolecular C–H functionalization of arenes. Mechanistic studies showed that Pd and Ag act in cooperation in the catalysis and the chiral bisphosphine ligand plays a bifunctional role, i.e., assisting the silver species in the cleavage of the aryl C–H bond, while inducing the enantioselectivity on direct complexation with palladium. This method provides an efficient approach to the corresponding chiral oxindoles with good enantiomeric excesses from a broad scope of arenes, including fluoroarenes, heteroarenes and several complex products derived from medicines or natural products.

Flexible perovskite solar cells (f-PSCs) have experienced rapid advancements due to the light-weight, flexibility, and solution processability of the perovskite materials, which prompted the power conversion efficiency (PCE) to 24.08%. However, f-PSCs still face challenges in terms of mechanical and environmental stability. This is primarily due to their inherent brittleness, the presence of residual tensile strain, and the high density of defects along the boundaries of perovskite grains. To this end, we carefully developed a cross-linkable elastomers 3-[(3-acrylamidopropyl)dimethylammonium] propanoate (ADP) with electrostatic dynamic bond, which could be in-situ cross-linked and coordinate with [PbI₆]⁴⁻ to regulate the crystallization process of perovskite. The cross-linked elastomers attached to the perovskite grain boundaries could release the remaining tensile strains and mechanical stresses, leading to enhanced stability and flexibility of the f-PSCs. More importantly, the electrostatic interaction between positive and negative groups of cross-linked elastomers and hydrogen bond formation between N–H and C=O accelerate the cross-linking of ADP, endowing the flexible perovskite films with self-healing ability under mild treating conditions (60 °C for 30 min). As a result, the device achieves a remarkable PCE of 23.53% (certified 23.16%). Additionally, the device exhibits impressive mechanical sustainability and durability, retaining over 90% of initial PCE even after undergoing 8,000 bending cycles.

Asymmetric reductive amination directly converts ketones and amines to alkylamines, which are important motifs in medicines. We report that cationic nickel complexes of chiral diphosphines promote enantioselective reductive amination of benzylic ketones with both arylamines and benzhydrazide. Isopropanol was used as a safe and cheap source of hydrogen instead of formic acid. The reaction can be readily applied to a concise synthesis of diarylethylamines, a class of neuroactive substances.

The effect of side-chain engineering of conjugated molecules on the morphology and device performance in binary organic solar cells has been widely investigated. However, this relationship has hardly been studied in the guest components of ternary organic solar cells. In this study, a family of non-fullerene guest acceptors, namely XY-3, XY-5 and XY-7, with hydrogen substituent, straight and branched alkyl chains on the bithiophene units, respectively, were designed and synthesized to understand their effects on aggregation properties and device performance. The straight and branched alkyl chains on the bithiophene units result in sightly blue-shifted absorption compared to the hydrogen substituent and the XY-7 demonstrates the most appropriate phase separation scale and the most balanced charge transport. Consequently, the OSCs based on D18:eC9:XY-7 achieve a high short-circuit current density (J_SC) and fill factor (FF), while maintaining the enhancement of the open-circuit voltage (V_OC) achieving an efficiency of 19.32%, exceeding those of D18:eC9, D18:eC9:XY-3, D18:eC9:XY-5 (PCE:18.28%, 19.04%, 18.75%, respectively). These results highlight that the side-chain engineering of Y series non-fullerene acceptors as the guest acceptors has great potential in optimizing morphology properties and promoting photovoltaic performance.

Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes (OLEDs), attributed to their unique emission properties originating from the doublet spin state. However, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength region. Designing luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission (383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons (PAHs) (2-naphthyl, 2a^I and 2b^I; 2-phenanthryl, 2a^II and 2b^II; 2-anthryl, 2a^III and 2b^III; 3-phenanthryl, 2a^IV and 2b^IV). Theoretical calculations reveal that the introduction of PAHs significantly increases the ΔE_D2-D1 in 2a^I–III and 2b^I–III compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1 is impeded, leading to a high yield of D2 emission and a suppressed Kasha’s rule, thereby overcoming the limitations imposed by their narrow bandgap. For 2a^IV and 2b^IV, despite a moderately large ΔE_D2-D1 value, the ΔE_D3-D1 value exceeds 1 eV, indicating that their emission likely originates from the D3 state. Furthermore, we utilized 2a^III and 2b^III as emissive materials in OLEDs, resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.

Recent years have witnessed the transformative impact from the integration of artificial intelligence with organic and polymer synthesis. This synergy offers innovative and intelligent solutions to a range of classic problems in synthetic chemistry. These exciting advancements include the prediction of molecular property, multi-step retrosynthetic pathway planning, elucidation of the structure-performance relationship of single-step transformation, establishment of the quantitative linkage between polymer structures and their functions, design and optimization of polymerization process, prediction of the structure and sequence of biological macromolecules, as well as automated and intelligent synthesis platforms. Chemists can now explore synthetic chemistry with unprecedented precision and efficiency, creating novel reactions, catalysts, and polymer materials under the data-driven paradigm. Despite these thrilling developments, the field of artificial intelligence (AI) synthetic chemistry is still in its infancy, facing challenges and limitations in terms of data openness, model interpretability, as well as software and hardware support. This review aims to provide an overview of the current progress, key challenges, and future development suggestions in the interdisciplinary field between AI and synthetic chemistry. It is hoped that this overview will offer readers a comprehensive understanding of this emerging field, inspiring and promoting further scientific research and development.

Exploration of single molecular species synchronously featured by long excitation/emission wavelength, accurate diagnosis, and effective therapy, remains supremely appealing to implement high-performance cancer phototheranostics. However, those previously established phototheranostic agents are undiversified and stereotyped in terms of structural skeleton, and generally exhibit insufficient phototheranostic outcomes. Herein, we innovatively utilized indanone-condensed thiadiazolo[3,4-g]quinoxaline (ITQ) as electron acceptor to construct novel photosensitizer with second near-infrared (NIR-II) emission. Experimental study and theoretical calculation demonstrated that comparing with the counterparts constituting by widely employed NIR-II building block benzobisthiadiazole (BBTD) and 6,7-diphenylthiadiazoloquinoxaline (DPTQ), ITQ-based photosensitizer (TITQ) showed superior aggregation-induced emission (AIE) characteristics, much stronger type-I reactive oxygen species (ROS) production, and prominent photothermal conversion capacity. Furthermore, TITQ nanoparticles with excellent biocompatibility were capable of effectively accumulating in the tumor site and visualizing tumor through fluorescence-photoacoustic-photothermal trimodal imaging with highly spatiotemporal resolution, and completely eliminating tumor by type-I photodynamic-photothermal therapy.

Organocatalytic cascade reactions represent a powerful strategy for the rapid construction of complex chiral molecules with multiple stereocenters from simple substrates under mild conditions. The intriguing structural feature and diverse reactivity of catalytically generated dienolate species render them competent and versatile intermediates for the development of practical and valuable cascade reactions. Over the past years, a plethora of innovative and pioneering noncovalent ammonium dienolate-mediated cascade reactions have been designed and implemented under the catalysis of chiral organocatalysts, making dienolate activation a general, robust, and complementary method for the functionalization of unsaturated carbonyl compounds and related substances. This review illustrates the recent advances in organocatalytic noncovalent ammonium dienolate-mediated cascade reactions (mainly from 2010 to 2023), including the cascade transformations of ammonium dienolates directly generated from unsaturated ketone/aldehyde, ester/lactone/azlactone, amide/lactam/pyrazolone/oxindole, and alkylidene nitrile compounds. The contents are arranged based on the reaction types of the ammonium dienolates, with an emphasis on cascade 2,5-, 3,5-, and 4,5-difunctionalizations of these intermediates. Furthermore, other cascade reactions involving the 1,3-, 2,3-, and even more complex 3,4,5-reactivities of ammonium dienolates were also discussed. The reaction pathway, reaction stereoinduction, and synthetic applications of the ammonium dienolate-mediated cascade reactions were highlighted throughout the article. As a stimulating and ever-growing research area, the organocatalytic noncovalent ammonium dienolate-mediated cascade reactions are expected to continue demonstrating their magic power for constructing chiral targets in the future and further expanding the boundaries of asymmetric catalysis.

The development of efficient Si–O bond formation reaction with 100% atom-economy, excellent functional group tolerance, and broad scope under mild conditions is highly desired due to the prevalence of silanol, silyl ether, and their derivatives in synthetic chemistry and materials science. Here, we have realized the Pd-catalyzed Si–O formation reaction via a Si–C activation approach with 100% atom-economy by employing silacyclobutanes (SCBs) and various hydroxy-containing substrates, including water, alcohols, phenols, and silanols. This protocol features a broad substrate scope, remarkable functional compatibility and mild conditions, providing a series of silanols, silyl ethers in high efficiency. Notably, this protocol could also be used for selective protection of hydroxy functionalities, and for the access of a class of novel polymers containing Si–O main chain. Preliminary mechanistic studies unveiled that this reaction underwent a Pd-catalyzed concerted ring-opening mechanism.

Developing highly sensitive optical thermometers is of great significance due to their capability to enable remote and non-contact temperature measurements, rendering them highly applicable in diverse and harsh environments. Herein we report a temperature-dependent phosphor of 0D metal halide hybrid by incorporating Bi³⁺ into the (MePPh₃)₂ZnCl₄ matrix. Through Bi³⁺ doping, the initially non-luminescent (MePPh₃)₂ZnCl₄ matrix exhibits a deep-blue emission centered at 453 nm, with a photoluminescence quantum yield (PLQY) of 5.71% and a Stokes shift of 75 nm at room temperature. Experimental characterization demonstrates that exciton-like luminescence of Bi³⁺ is mainly responsible for the blue emission. Single crystals of Bi³⁺-doped (MePPh₃)₂ZnCl₄ show an unusual correlation between photoluminescence (PL) lifetime and temperature. Particularly, the dependence of luminescence lifetime on temperature is most remarkable in the temperature range of 80 to 100 K with an exceptional sensitivity up to 0.09 K⁻¹, representing one of the best levels for thermometry based on PL decay lifetime. Our work not only provides a viable strategy for designing a novel, environmentally friendly, and stable blue emitter, but also paves the way for precise thermometric application at low temperature.