RSC主编推荐：有机领域精彩文章快览（免费阅读原文）

英国皇家化学会（RSC）是一个拥有175年历史的面向全球化学家的非营利会员制机构，旗下拥有43种期刊，其中很多在化学领域有很高影响力。为了进一步帮助广大读者追踪科技前沿热点，X-MOL团队与英国皇家化学会合作，推出英国皇家化学会期刊主编推荐的精彩文章快览，本期文章属“有机领域”，英文点评来自英国皇家化学会期刊的主编。如果大家对我们的解读有更多的补充和点评，欢迎在文末写评论发表您的高见！

Organic Chemistry Frontiers (IF: 4.693)

1. The effect of a highly twisted C=C double bond on the electronic structures of 9,9'-bifluorenylidene derivatives in the ground and excited states

Org. Chem. Front., 2017, 4, 650-657

DOI: 10.1039/C7QO00125H, Research Article

Methyl-substituted 9,9'-bifluorenylidene (9,9'-BF) derivatives in which two planar fluorene units are connected through a C=C double bond were synthesized. The C=C double bond is twisted owing to the steric crowding between the fluorene units, and by introducing substituents at 1,1'-positions (inner space of 9,9'-BF) it becomes more twisted. Indeed, single crystal X-ray structural analysis and theoretical calculation reveal that the dihedral angle between two fluorene π-planes of a 1,1'-dimethyl-substituted 9,9'-BF is 56°, which is clearly larger than those of pristine 9,9'-BF (42°) and 1-methyl-substituted 9,9'-BF (50°). The twisted conformation of 1,1'-dimethyl-substituted 9,9'-BF facilitates the cis–trans isomerization process which was quantitatively assessed by variable-temperature NMR measurements. The 9,9'-BF derivatives with different numbers of methyl groups also exhibit remarkable changes in optoelectronic properties, primarily because of the change in the twisting angle of the central C=C double bond. Theoretical calculation further indicates that the electronic structures of methyl-substituted 9,9'-BF derivatives in the excited states are considerably different from those of pristine 9,9'-BF.

来自日本的科学家合成了以C=C双键连接两个平面芴单元的甲基取代的9,9'-二亚芴基（9,9'-BF）衍生物。由于芴单元之间的空间拥挤，C=C双键发生了扭曲，而在1,1'位置（9,9'-BF的内部空间）引入取代基后，C=C双键变得更加扭曲。通过X射线单晶结构分析和理论计算表明，1,1'-二甲基取代的9,9'-BF的两个芴π面之间的二面角为56°，明显大于原始的9,9'-BF（42°）和1-甲基取代的9,9'-BF（50°）。1,1'-二甲基取代的9,9'-BF的扭曲构象有助于顺式-反式异构化过程，并可通过变温NMR测量进行定量分析。具有不同甲基数的9,9'-BF衍生物在光电性能方面也呈现出显著的变化，主要是由于中心C=C双键扭转角度发生改变。理论计算进一步表明，激发态的甲基取代的9,9'-BF衍生物的电子结构与原始9,9'-BF的电子结构有很大不同。

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2. Synthesis of a figure-eight azahelicene dimer with high emission and CPL properties

Org. Chem. Front., 2017, 4, 664-667

DOI: 10.1039/C6QO00629A, Research Article

Circular polarized luminescence (CPL) is useful for advanced optical devices. However, it is difficult to achieve strong emission and high CPL properties at the same time. A bisbutadiyne bridged azahelicene dimer with a figure-eight shape was synthesized through the Glaser–Hay homo-coupling reaction with diethynyl-azahelicene. The desired compound exhibited both high fluorescence quantum yield and the g value. The enhancement of both the CPL properties and emission efficiency is due to the rigid conformation of the dimer. These findings are promising to establish the design concept of small organic molecules with excellent CPL features.

圆偏振发光（CPL）可以应用于高级光学器件的开发。然而，要同时实现强发射和高CPL性能却十分困难。来自日本的研究者通过使用二乙炔基-氮杂螺烯的Glaser–Hay偶联反应合成了“8”字形的双丁二炔基桥连的氮杂螺烯二聚体。目标化合物同时表现出高荧光量子产率和g值，而且由于二聚体的刚性构象，CPL性能和发射效率都得到了加强。这些发现有助于设计构建具有卓越CPL性能的有机小分子。

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3. A cross-coupling-annulation cascade from peri-dibromonaphthalimide to pseudo-rylene bisimides

Org. Chem. Front., 2016, 3, 1435-1442

DOI: 10.1039/C6QO00421K, Research Article

A synthetic method was reported to annulate naphthalimide moieties at different positions of a pyrenecore by a cascade reaction involving palladium-mediated Suzuki–Miyaura cross-coupling and direct C–H arylation. This reaction affords a new class of rylene bisimides termed as pseudo-rylene bisimides. The Pd-mediated reactions of peri-dibromonaphthalimide and pyrene boronic acid esters lead exclusively to six-membered ring annulation by a cascade C–C bond formation, for which a mechanistic rationale is proposed. Depending on the molecular geometry of the new pseudo-rylene bisimides, their optical properties resemble those of zethrene or terrylene bisimides, or polycyclic aromatic hydrocarbons like coronenes. The structural integrity of this new type of pseudo-rylene bisimides was confirmed by single crystal X-ray analysis.

本文报道了一种新的合成方法，通过钯参与的Suzuki-Miyaura交叉偶联及直接C-H键芳基化的串联反应，可以在芘的不同位置构建环状萘酰亚胺结构。该反应能生成一类被称为拟苝双酰亚胺的新的苝双酰亚胺结构。这项工作通过钯参与的邻二溴萘酰亚胺和芘硼酸酯之间C-C键形成的串联过程高效得到六元环产物，并提出了该反应的机理依据。受几何构型的影响，拟苝双酰亚胺分子的光学性质类似于zethrene或三萘嵌二苯双酰亚胺，或诸如晕苯的多环芳香烃。单晶X射线分析证实了这种新型拟苝双酰亚胺的完整分子结构。

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Chemical Science (IF: 9.144)

1. Probe for simultaneous membrane and nucleus labeling in living cells and in vivo bioimaging using a two-photon absorption water-soluble Zn(II) terpyridine complex with a reduced π-conjugation system

Chem. Sci., 2017, 8, 142-149

DOI: 10.1039/C6SC02342H

Scientists from Hefei, Nanjing and Sweden report several TPA active zinc-terpyridine complexes, which can be used as imaging probes in living cells and zebrafish. These complexes are shown to penetrate into the central nervous system through the blood-brain barrier.

来自安徽大学、南京大学以及瑞典的科学家报道了几种TPA活性锌-三联吡啶络合物用作活细胞和斑马鱼的成像探针，这些络合物可通过血脑屏障渗入中枢神经系统。

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2. Aminofluorination: transition-metal-free N-F bond insertion into diazocarbonyl compounds

Chem. Sci., 2016, 7, 1786-1790

DOI: 10.1039/c5sc04237b

Researchers in the Fujian province have achieved geminal aminofluorination of diazocarbonyl compounds for the first time. The reaction is transition-metal-free and occurs under mild conditions. Kinetic studies and DFT calculations provide an insight into the potential mechanism.

来自中科院福建物构所的研究人员首次实现了重氮羰基化合物的偕-胺氟化。该反应无过渡金属的参与，在温和条件下进行。通过动力学研究和DFT计算，深入了解该反应可能的机理。

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