Chemistry - A European Journal最新文献

The development of innovative and sustainable synthetic methodologies is crucial to address the increasing demand for environmentally benign practices in all domains of organic chemistry. In this regard, harnessing visible light as the sole energy input is particularly attractive. Diazo compounds, being highly versatile reagents with notable reactivity and ready accessibility, are well-suited for photochemical activation, which offers a promising, eco-friendly alternative to traditional transition-metal-catalyzed processes. In this perspective, we report generalized photochemical pathways for the synthesis of benzene fused 1,4- and 1,3-diazines from 1,4- and 1,5-aza bis-nucleophiles and various diazo compounds, employing water as the sole and distinct solvent under aerobic presence. These protocols involve the direct photoinduced generation of carbenes from diazo compounds, averting the need of any photocatalyst, which then opts [4+2] or [5+1]-annulation pathway and offers distinct products. The detailed insights into the reaction pathways are investigated through several control experiments and DFT studies. Strategically it is also possible to construct a 5-membered aza-heterocyclic core applying the same photochemical approach. Finally, the late-stage modifications of quinoxalinone and quinoxaline scaffold applying the photoinduced C-H activation technique generate the structurally diverse spiroindene compounds, including steroid-embedded di-aza heterocycle.

A new "Porphyrin-Geländer" (PoGe) macrocycle rac-PoGe[Zn, Zn] embodying a twisted butadiyne-linked porphyrin dyad as the banister was designed and synthesized according to a previously published successful design principle for Geländer molecules. The C₂-symmetric properties of rac-PoGe[Zn, Zn] were revealed by detailed 2D NMR analysis. Postsynthesis modification consisting of central metal ion exchange in the porphyrin moieties led to PoGe macrocycles rac-PoGe[2H, 2H] and rac-PoGe[Cu, Cu] and was demonstrated to lead to finely tunable absorption and emission spectra, reaching in the near-IR region. CSP-HPLC resolved all rac-PoGe[M, M] into their (P) and (M) enantiomers, which were analyzed by UV-Vis, fluorescence and ECD spectroscopy. The absolute configuration was assigned by the exciton chirality method (ECM) and corroborated by comparing experimental and simulated ECD spectra.

Ammonia concentration acts as a "multifunctional structure-directing factor" throughout the entire growth of Li-rich Mn-based oxide (LRMO) precursors in coprecipitation process. Thus, this study investigates the effect of ammonia concentration on the precursor structure and morphology evolution. It is verified that ammonia concentration can significantly influence the preferential growth of crystallites and the agglomeration behavior of secondary particles. At an optimized ammonia concentration, the Mn_0.675Co_0.1625Ni_0.1625CO₃ precursor exhibited preferential growth along the (012) crystallographic plane, facilitating an ordered structural arrangement and suppressing the agglomeration of secondary particle. After lithiation, the resulting LRMO material exhibits an enhanced Li⁺ diffusion, endowing the material with higher initial capacity, improved rate performance, and superior cycling stability. Furthermore, this work establishes a clear correlation between the lattice parameters of the LRMO material and its Li⁺ transport and storage properties. These findings offer valuable mechanistic insights and a practical synthesis strategy for enhancing the electrochemical performance of LRMO cathodes by precisely controlling precursor crystallization and microstructure.

The efficient separation and migration of photogenerated charge carriers remains a major challenge in polymer-based photocatalysis. Building planar structures through ladder-type polymers has emerged as an effective strategy to enhance charge carrier dynamics. In this context, we investigate the crucial yet overlooked role of structural isomerization in such systems. Herein, we report two isomeric ladder polymers with coplanar backbones, PAE-L and PAE-Z, to systematically investigate the influence of molecular configuration on photocatalytic performance. The optimized PAE-L exhibits enhanced light-harvesting capability, strengthened π-π stacking, and superior charge transport properties, leading to remarkable photocatalytic hydrogen evolution activity. This work provides a reference for the design and performance optimization of efficient coplanar conjugated polymer photocatalysts.

Molecules that violate Hund's rule by exhibiting an inverted singlet-triplet gap (STG), where the first excited singlet ( $S_1$ ) lies below the triplet ( $T_1$ ), are rare but hold great promise as efficient fifth-generation light emitters. Azaphenalenes (APs) represent one of the few known molecular classes capable of such inversion of the $S_1$ / $T_1$ energy ordering, yet a systematic exploration of all unique APs is lacking. Here, we investigate 104 distinct APs and classify them based on their adherence to or deviation from Hund's rule using $S_1$ - $T_1$ gaps computed with the second-order coupled-cluster method employing the Laplace transform (L-CC2). To capture substitution-dependent pseudo-Jahn-Teller distortions that are inadequately described by MP2 and DFT methods, we employ a focal-point extrapolation scheme to obtain near-CCSD(T)/cc-pVTZ-quality geometries. We find 3 APs to undergo $D_{3h}\to C_{3h}$ and 10 to show $C_{2v}\to C_s$ symmetry lowering, leading to a total of 117 configurations of 104 unique APs. Our study identifies top candidates with inverted STGs, revealing how substitution and symmetry-lowering modulate these gaps to uncover new stable AP cores that provide promising targets for designing molecular light-emitters.

The targeted degradation of RNA, particularly long noncoding RNAs (lncRNAs), holds immense potential for therapeutic interventions in diseases associated with aberrant RNA regulation. Here, we introduce a novel Proximity-Induced Nucleic Acid Degrader (PINAD-1), a first-in-class small molecule that selectively induces the degradation of MALAT1, a lncRNA implicated in the regulation of metastatic processes. PINAD-1 is designed by conjugating a binder specific for the triple helix structure of MALAT1 to an imidazole-based RNA-degrading warhead, enabling specific cleavage of the MALAT1 transcript in vitro and in cellulo, with minimal off-target effects on the structurally similar NEAT1 lncRNA. Through mechanistic studies, we show that effective RNA degradation is not solely dependent on proximity but requires a precise structural context, as demonstrated by the differential activity of PINAD-1 compared to the structurally analogous but functionally inert conjugate PINAD-2. Our findings underscore the importance of binder-induced destabilization and RNA geometry in facilitating RNA degradation. This work lays the foundation for the design of bifunctional small-molecule RNA degraders as powerful tools for the modulation of structured noncoding RNAs, offering potential applications in RNA-based therapeutics.

The spinel compound LiNi_0.5Mn_1.5O₄ (LNMO) has attracted increasing attention as a potential cathode material for high-energy lithium-ion batteries (LIBs) of the next generation. Despite its attractive properties, LNMO suffers from transition-metal ion dissolution and pronounced capacity fading, which significantly limit its practical implementation. To address these limitations, Zn is introduced into the LNMO structure to prepare Zn-doped LNMO, designed to stabilize the 16c and 8a sites and thus improve its electrochemical performance. This doping approach improves the structural robustness of LNMO and significantly suppresses Mn dissolution during electrochemical cycling. Even after 1000 cycles at a current rate of 1 C (1 C = 147 mA g^-1), the Zn-LNMO sample maintains 81.2% of its original capacity, demonstrating substantially improved capacity retention. Moreover, the Zn-LNMO electrode maintains 98.8% of its initial voltage after 1000 cycles, and the corresponding average decline in voltage is as low as 0.06 mV for each cycle. This study establishes an atomically engineered doping concept that can be generalized to various cathode systems and serves as an effective guideline for designing high-performance LIBs.

Herein, we present a highly efficient method for the late-stage introduction of "clickable" alkyne moieties into different (hetero)arene scaffolds. A highly efficient dual ligand-based palladium catalyst combining an N-acylsulfonamide (NASA) ligand with an N-heterocycle enables the introduction of acrylate moiety bearing a terminal alkyne via nondirected C─H activation, providing a versatile platform for subsequent bioconjugation or activity-based protein profiling (ABPP) applications. The utility of the method is demonstrated through a broad substrate scope and the subsequent use of the obtained products in representative click reactions.

The efficient separation and transfer of photogenerated charge carriers remain a difficult challenge in photocatalysis. While the heterojunctions are an effective strategy for promoting photogenerated charge separation, inefficient migration at the interface often hinders the development. Herein, we report a core-shell organic-inorganic hybrid system, TiO₂@3-aminophenol formaldehyde resin spheres ({001}-TiO₂@APF) for photocatalytic water treatment. The {001}-TiO₂@APF heterojunction achieves a 100% degradation efficiency of glyphosate in 6 h with a reaction rate constant of 0.0068 min^-1, which is 6.2 times that of APF (0.0011 min^-1) and 1.3 times that of bare TiO₂ (0.0051 min^-1). XPS analysis confirms the formation of Ti-O-C covalent bonds at the organic-inorganic interface, which effectively addresses the charge transport challenge and facilitates rapid carrier migration across the heterojunction. This work underscores the importance of atomic-level interfacial engineering in constructing high-efficiency inorganic-organic photocatalysts for sustainable water purification.

Nerve agents pose severe risks to human health, underscoring the need for efficient decontamination strategies. This study explores metal-organic frameworks (MOFs) as catalytic platforms owing to their structural tunability, redox-active metal centers, and abundance of Lewis acidic sites. Single- and bimetallic UiO-series MOFs incorporating Ce(IV) and Zr(IV) (confirmed by inductively coupled plasma mass spectrometry) were synthesized using different approaches, including ligand exchange and controlled crystal growth, with four ligands: BDC, BDC-NH₂, BDC-NO₂, and BDC-(OH)₂. These frameworks were systematically evaluated for the hydrolysis of p-nitrophenyl phosphate (PNPP), a simulant for G- and V-type nerve agents (e.g., sarin, VX). The design strategy leverages the redox activity and cooperativity of Ce/Zr nodes, alongside the caging effect of the MOF architecture, to enhance catalytic efficacy. Density functional theory (DFT) calculations provided mechanistic insights into sarin degradation, revealing how metal composition and linker functionality govern substrate binding and activation. Experimental results demonstrated that bimetallic Ce/Zr-MOFs with electron-withdrawing functional groups exhibit significantly accelerated hydrolysis under basic aqueous conditions. Notably, a Ce/Zr-MOF with -NO₂ functionality achieved the shortest half-life of 1.16 min. These findings highlight Ce/Zr-UiO frameworks as promising candidates for real-world nerve agent decontamination technologies.