《自然》（20240704出版）一周论文导读

编译 | 未玖

Nature,  4 July 2024, VOL 631, ISSUE 8019

《自然》2024年7月4日，第631卷，8019期

材料科学Materials Science

Fabrication of red-emitting perovskite LEDs by stabilizing their octahedral structure

稳定八面体结构制备红色发光钙钛矿LED

▲ 作者：Lingmei Kong, Yuqi Sun, Bin Zhao, Kangyu Ji, Jie Feng, Jianchao Dong, et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07531-9

▲ 摘要：

基于金属卤化物钙钛矿（PeLEDs）的发光二极管（LEDs）具有高色彩质量和易于溶液处理的优点，是全彩和高清显示器颇有前景的候选者。尽管人们在应用溴化铅钙钛矿的绿色PeLEDs中取得了巨大成功，但使用碘基对应物实现纯红色（620~650 nm）LEDs仍颇具挑战性，因其受到低本征带隙的限制。

研究组报道了整个纯红色区域的高效和颜色稳定的PeLEDs，通过将双端锚定配体分子掺杂至纯碘钙钛矿中，在638 nm处的峰值外量子效率达到28.7%。他们证明了有机插层阳离子的一个关键功能是通过与暴露的铅离子配位和增强与碘的氢键来稳定铅碘八面体。该分子协同促进光谱调制，促进钙钛矿量子阱之间的电荷转移，并减少电偏压下的碘迁移。

研究组实现了碘基钙钛矿薄膜的连续可调发射波长，并抑制了由于离子钙钛矿中铅碘键能随着带隙增加而降低导致的能量损失。重要的是，所得器件在初始亮度为100 cd m?2时表现出杰出的光谱稳定性和超过7600 min的半衰期。

▲ Abstract：

Light-emitting diodes (LEDs) based on metal halide perovskites (PeLEDs) with high colour quality and facile solution processing are promising candidates for full-colour and high-definition displays. Despite the great success achieved in green PeLEDs with lead bromide perovskites, it is still challenging to realize pure-red (620–650?nm) LEDs using iodine-based counterparts, as they are constrained by the low intrinsic bandgap. Here we report efficient and colour-stable PeLEDs across the entire pure-red region, with a peak external quantum efficiency reaching 28.7% at 638?nm, enabled by incorporating a double-end anchored ligand molecule into pure-iodine perovskites. We demonstrate that a key function of the organic intercalating cation is to stabilize the lead iodine octahedron through coordination with exposed lead ions and enhanced hydrogen bonding with iodine. The molecule synergistically facilitates spectral modulation, promotes charge transfer between perovskite quantum wells and reduces iodine migration under electrical bias. We realize continuously tunable emission wavelengths for iodine-based perovskite films with suppressed energy loss due to the decrease in bond energy of lead iodine in ionic perovskites as the bandgap increases. Importantly, the resultant devices show outstanding spectral stability and a half-lifetime of more than 7,600?min at an initial luminance of 100?cd?m?2.

化学Chemistry

Expanding chemistry through in vitro and in vivo biocatalysis

通过体外和体内生物催化扩展化学

▲ 作者：Elijah N. Kissman, Max B. Sosa, Douglas C. Millar, Edward J. Koleski, Kershanthen Thevasundaram & Michelle C. Y. Chang

▲ 链接：

https://www.nature.com/articles/s41586-024-07506-w

▲ 摘要：

生命系统包含一个巨大的代谢反应网络，为化学过程提供了丰富的酶和细胞作为潜在生物催化剂。

蛋白质和细胞生物催化剂的特性（即高选择性、在环境友好条件下控制反应序列和操作的能力）提供了高效生产分子的方法，同时降低了工业化学的成本和环境影响。此外，生物催化提供了产生化学合成可能无法获得的化学结构和功能的机会。

研究组综合考虑了酶、生物合成途径和细胞工程的发展，使其能够用于催化新的化学和其他方向。

▲ Abstract：

Living systems contain a vast network of metabolic reactions, providing a wealth of enzymes and cells as potential biocatalysts for chemical processes. The properties of protein and cell biocatalysts—high selectivity, the ability to control reaction sequence and operation in environmentally benign conditions—offer approaches to produce molecules at high efficiency while lowering the cost and environmental impact of industrial chemistry. Furthermore, biocatalysis offers the opportunity to generate chemical structures and functions that may be inaccessible to chemical synthesis. Here we consider developments in enzymes, biosynthetic pathways and cellular engineering that enable their use in catalysis for new chemistry and beyond.

Dynamic stereomutation of vinylcyclopropanes with metalloradicals

乙烯基环丙烷与金属自由基的动态立体变化

▲ 作者：Marvin Mendel, Teresa M. Karl, Jegor Hamm, Sherif J. Kaldas, Theresa Sperger, Bhaskar Mondal, et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07555-1

▲ 摘要：

在化学过程中，对更大可持续性和更低能源使用不断增长的需求要求采用全新的方法和反应性原理。在这种背景下，非贵金属中奇数氧化态通过金属自由基催化产生迥然不同的反应模式而显著流行，具有尚未开发的潜力。

与公认的反应性范式相反，有机自由基在加入乙烯基环丙烷后，在应变释放下导致快速开环，这种转变广泛用作自由基介导的机械探针（自由基时钟）。研究组表明，金属基自由基（即Ni(I)金属自由基）触发可逆顺式/反式异构化而非开环。异构化在手性反转下进行且取决于取代模式，在室温下不到5分钟内发生，仅需要添加非贵重催化剂。

综合计算和实验机制研究支持金属自由基催化是这种彻底反应性的起源，合理化了观察到的立体反转，揭示了该过程的关键反应性特征，包括其可逆性。这些发现使得对映纯顺式/反式混合物通过多个Ni(I)催化轮迭代热力学富集为单个非对映体，并扩展到二乙烯基环丙烷，这构成了天然产物和全合成中的战略基序。

反式异构体通常需要在大约200℃的温度下加热才能在外消旋作用下触发热异构化，以生成顺式二乙烯基环丙烷，然后经历简单的Cope型重排，但该研究显示，类似的反热力学过程在温和条件下在Ni(I)金属催化下进行，而不会损失任何立体化学完整性，从而可以温和且立体化学纯地获得七元环、稠环系统和螺环。

▲ Abstract：

The ever increasing demands for greater sustainability and lower energy usage in chemical processes call for fundamentally new approaches and reactivity principles. In this context, the pronounced prevalence of odd-oxidation states in less precious metals bears untapped potential for fundamentally distinct reactivity modes via metalloradical catalysis. Contrary to the well-established reactivity paradigm that organic free radicals, upon addition to a vinylcyclopropane, lead to rapid ring opening under strain release—a transformation that serves widely as a mechanistic probe (radical clock) for the intermediacy of radicals—we herein show that a metal-based radical, that is, a Ni(I) metalloradical, triggers reversible cis/trans isomerization instead of opening. The isomerization proceeds under chiral inversion and, depending on the substitution pattern, occurs at room temperature in less than 5?min, requiring solely the addition of the non-precious catalyst. Our combined computational and experimental mechanistic studies support metalloradical catalysis as origin of this profound reactivity, rationalize the observed stereoinversion and reveal key reactivity features of the process, including its reversibility. These insights enabled the iterative thermodynamic enrichment of enantiopure cis/trans mixtures towards a single diastereomer through multiple Ni(I) catalysis rounds and also extensions to divinylcyclopropanes, which constitute strategic motifs in natural product- and total syntheses. While the trans-isomer usually requires heating at approximately 200?°C to trigger thermal isomerization under racemization to cis-divinylcyclopropane, which then undergoes facile Cope-type rearrangement, the analogous contra-thermodynamic process is herein shown to proceed under Ni(I) metalloradical catalysis under mild conditions without any loss of stereochemical integrity, enabling a mild and stereochemically pure access to seven-membered rings, fused ring systems and spirocycles.

A deconstruction–reconstruction strategy for pyrimidine diversification

解构-重构策略助力嘧啶多样化

▲ 作者：Benjamin J. H. Uhlenbruck, Celena M. Josephitis, Louis de Lescure, Robert S. Paton & Andrew McNally

▲ 链接：

https://www.nature.com/articles/s41586-024-07474-1

▲ 摘要：

构效关系（SAR）研究是药物和农用化学品开发的基础，但只有少数合成策略适用于小分子候选物中经常遇到的氮杂芳烃。

研究组提出了一种替代方法，将含嘧啶的化合物转化为各种其他氮杂芳烃。将嘧啶转化为相应的N—芳基嘧啶鎓盐，可裂解为三碳亚氨基烯胺构建块，用于各种杂环形成反应。

这种解构—重建序列使初始嘧啶核多样化，并能够获得如唑类的各种杂环。实际上，这种方法实现了在复杂分子上形成杂环，从而生成其他方法难以获得的类似物。研究组预计这种解构—重建策略将扩展到其他杂环类。

▲ Abstract：

Structure–activity relationship (SAR) studies are fundamental to drug and agrochemical development, yet only a few synthetic strategies apply to the nitrogen heteroaromatics frequently encountered in small molecule candidates. Here we present an alternative approach in which we convert pyrimidine-containing compounds into various other nitrogen heteroaromatics. Transforming pyrimidines into their corresponding N-arylpyrimidinium salts enables cleavage into a three-carbon iminoenamine building block, used for various heterocycle-forming reactions. This deconstruction–reconstruction sequence diversifies the initial pyrimidine core and enables access to various heterocycles, such as azoles. In effect, this approach allows heterocycle formation on complex molecules, resulting in analogues that would be challenging to obtain by other methods. We anticipate that this deconstruction–reconstruction strategy will extend to other heterocycle classes.

地球科学Earth Science

2023 summer warmth unparalleled over the past 2,000 years

2023年夏季为两千年来最热

▲ 作者：Jan Esper, Max Torbenson & Ulf Büntgen

▲ 链接：

https://www.nature.com/articles/s41586-024-07512-y

▲ 摘要：

包括异常温暖的北半球夏季在内，2023年被报道为有记录以来最热的一年。然而，将最近的人为变暖与过去的自然变率相关联颇具挑战性，因为19世纪以来的稀少气象记录往往高估了温度。

研究组将观测和重建的6~8月地表气温结合起来，表明2023年是过去2000年来北半球温带最热的夏季，比自然气候变率的95%置信区间高出0.5℃以上。2023年6~8月升温与公元536年重建最冷夏季的对比显示，前人类世至2023年的最大温差为3.93℃。

尽管2023年与温室气体引起的变暖趋势一致，且正在进行的厄尔尼诺事件加剧了这一趋势，但该极端事件强调了实施国际碳减排协议的紧迫性。

▲ Abstract：

Including an exceptionally warm Northern Hemisphere summer, 2023 has been reported as the hottest year on record. However, contextualizing recent anthropogenic warming against past natural variability is challenging because the sparse meteorological records from the nineteenth century tend to overestimate temperatures. Here we combine observed and reconstructed June–August surface air temperatures to show that 2023 was the warmest Northern Hemisphere extra-tropical summer over the past 2,000 years exceeding the 95% confidence range of natural climate variability by more than 0.5 °C. Comparison of the 2023 June–August warming against the coldest reconstructed summer in CE 536 shows a maximum range of pre-Anthropocene-to-2023 temperatures of 3.93?°C. Although 2023 is consistent with a greenhouse-gases-induced warming trend that is amplified by an unfolding El Ni?o event, this extreme emphasizes the urgency to implement international agreements for carbon emission reduction.

Global variability in atmospheric new particle formation mechanisms

大气新粒子形成机制的全球变率

▲ 作者：Bin Zhao, Neil M. Donahue, Kai Zhang, Lizhuo Mao, Manish Shrivastava, Po-Lun Ma, et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07547-1

▲ 摘要：

气溶胶污染研究和气候变化评估的一个关键挑战是了解大气气溶胶颗粒最初如何形成。虽然新粒子形成（NPF）机制已在特定地点描述过，但在大多数地区，由于大气模型模拟关键NPF过程的能力有限，该机制在很大程度上仍不确定。

研究组综合了分子水平的实验，在一个完全耦合的全球气候模型中建立了11类NPF机制和前驱体气体复杂化学转化的综合表征。综合模拟和观测结果表明，主要的NPF机制在全球范围内是不同的，并且随区域和高程而变化。

在大多数气溶胶浓度高或气溶胶辐射强迫大的地区，以前被忽视或代表性不足的涉及有机物、胺、碘氧酸和HNO3的机制可能主导着NPF；这些区域包括海洋和人为污染的大陆边界层，以及热带雨林和亚洲季风区上空的对流层上层。这些代表性不足的机制在其他区域也发挥着显著作用，例如太平洋和大西洋对流层上层。

因此，NPF在对流层下层不同区域以0.5%过饱和度形成云的核中占不同比例（10~80%）。对全球NPF机制的综合模拟有助于改进气溶胶气候效应的估计和源归因。

▲ Abstract：

A key challenge in aerosol pollution studies and climate change assessment is to understand how atmospheric aerosol particles are initially formed. Although new particle formation (NPF) mechanisms have been described at specific sites, in most regions, such mechanisms remain uncertain to a large extent because of the limited ability of atmospheric models to simulate critical NPF processes. Here we synthesize molecular-level experiments to develop comprehensive representations of 11 NPF mechanisms and the complex chemical transformation of precursor gases in a fully coupled global climate model. Combined simulations and observations show that the dominant NPF mechanisms are distinct worldwide and vary with region and altitude. Previously neglected or underrepresented mechanisms involving organics, amines, iodine oxoacids and HNO3 probably dominate NPF in most regions with high concentrations of aerosols or large aerosol radiative forcing; such regions include oceanic and human-polluted continental boundary layers, as well as the upper troposphere over rainforests and Asian monsoon regions. These underrepresented mechanisms also play notable roles in other areas, such as the upper troposphere of the Pacific and Atlantic oceans. Accordingly, NPF accounts for different fractions (10–80%) of the nuclei on which cloud forms at 0.5% supersaturation over various regions in the lower troposphere. The comprehensive simulation of global NPF mechanisms can help improve estimation and source attribution of the climate effects of aerosols.