Silicon semiconductor technology has driven the profusion of information technology into every aspect of modern life. An obvious example of this is the emergence of portable electronic devices, such as cellular phones (mobile phones), personal digital assistants, palmtop computers, etc., that are rapidly becoming essential. These share a common Achilles heel, namely, battery life. The most obvious way to attack this problem is through replacement of the power hungry back-lit liquid-crystal displays (LCDs) that reside in all lightweight devices. It is this impetus that has brought organic light-emitting devices (OLEDs) to the forefront of modern materials science. The ability to mass produce thin, efficient, bright displays from organic polymers and small molecules that can supplant modern LCDs depends almost entirely on the ability to create new materials that can undergo efficient electroluminescence at a variety of wavelengths. This has lead to many publications and patents but to date has failed to produce an efficient, cheap, and robust blue-light emitter. It is, of course, not an easy task to find a small molecule that possesses not only a very large bandgap but also stability to the harsh electrochemical environment of OLEDs and a very large quantum yield in the solid state. One class of molecules in particular, fluorenes—especially spirofluorenes—has received much attention because of the outstanding properties in this area, but lengthy syntheses and low-yielding steps, such as boronic acid/ester formations, are less than ideal for singlelayer/host materials. In an effort to redirect some of the explorations, we have investigated a close cousin of fluorenes—fluoranthenes—for applications as blue-light emitters in OLEDs (Scheme 1). In particular, we have studied 7,8,10triphenylfluoranthene (TPF), a highly luminescent solid-state blue-light-emitting small molecule, which can be obtained in two steps from commercial starting materials. After the elucidation of the structure of fluoranthene at the turn of the 20th century, the chemistry of fluoranthenes evolved rapidly. Studies of the interesting photophysical properties followed, but interest in fluoranthenes faded fast. Of particular note is the synthesis of fluoranthene derivatives by a double Knoevenagel condensation between 2-propanone and acenaphthenequinone, which allows functionalization at the carbon 7 and 10 positions. A subsequent Diels–Alder addition allows further functionalization at the 8 and 9 positions. Finally, starting from bromoacenapthenequinone, the carbon 3 position is open to functionalization. With these synthetic tools in hand, we set about finding a fluoranthene derivative that would not crystallize and would remain highly blue-luminescent in the solid state. The most obvious candidate was a perphenylated derivative, which, due to steric hindrance, would keep the phenyl rings out of plane, thus presenting a ball-like surface to resist crystallization and reduce facial contacts that can lead to excimer quenching and bathochromic shifts in emission. To our surprise, only the 7,8,10-triphenyl derivative (2, Scheme 2) exhibited strong luminescence; the 7,8,9,10-tetraphenyl derivative is essentially non-fluorescent (in the solid state), and the 3,7,8,9-tetraphenyl derivative suffers from a large bathochromic shift in the solid state. The introduction of other functionality (e.g., esters, carboxylic acids, and halides) led to green/yellow emission and/or solubility problems. As with the other derivatives, 7,8,10-triphenylfluoranthene was synthesized via the Knoevenagel/Diels–Alder method (Scheme 2) from acenapthenequinone, diphenylacetone, and phenylacetylene, using only ethanol (EtOH) and (optionally) xylenes for solvents; all are inexpensive and readily available. Purification is uncompliC O M M U N IC A IO N S

中文翻译：

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具有坚固荧光团的高效蓝光电致发光器件：7,8,10-三苯基荧蒽

硅半导体技术推动信息技术大量涌入现代生活的方方面面。一个明显的例子是便携式电子设备的出现，例如蜂窝电话（移动电话）、个人数字助理、掌上电脑等，它们正在迅速变得必不可少。这些都有一个共同的致命弱点，即电池寿命。解决这个问题的最明显方法是更换所有轻量级设备中耗电的背光液晶显示器 (LCD)。正是这种推动力将有机发光器件 (OLED) 带到了现代材料科学的前沿。量产薄、高效、可以取代现代液晶显示器的有机聚合物和小分子的明亮显示器几乎完全取决于创造能够在各种波长下进行有效电致发光的新材料的能力。这导致了许多出版物和专利，但迄今为止未能生产出高效、廉价且坚固的蓝光发射器。当然，要找到一种小分子不仅具有非常大的带隙，而且对 OLED 的恶劣电化学环境具有稳定性，并且在固态下具有非常大的量子产率，这当然不是一件容易的事。特别是一类分子芴——尤其是螺芴——因其在该领域的突出特性而备受关注，但合成过程冗长且产率低，例如硼酸/酯的形成，不是理想的单层/主体材料。为了重新引导一些探索，我们研究了芴的近亲——荧蒽——在 OLED 中用作蓝光发射器（方案 1）。特别是，我们研究了 7,8,10 三苯基荧蒽 (TPF)，这是一种高发光固态蓝光发射小分子，可以从商业起始材料分两步获得。20世纪初，荧蒽的结构被阐明后，荧蒽的化学发展迅速。随后对有趣的光物理性质进行了研究，但对荧蒽的兴趣迅速消退。特别值得注意的是通过 2-丙酮和苊醌之间的双重 Knoevenagel 缩合合成荧蒽衍生物，这允许在碳 7 和 10 位进行功能化。随后的 Diels-Alder 添加允许在 8 位和 9 位进一步功能化。最后，从溴代萘醌开始，碳 3 位对官能化开放。有了这些合成工具，我们着手寻找一种不会结晶并在固态下保持高度蓝光发光的荧蒽衍生物。最明显的候选物是全苯基衍生物，由于空间位阻，它会使苯环保持在平面外，从而呈现出球状表面以抵抗结晶并减少可导致准分子猝灭和发射红移的面部接触. 令我们惊讶的是，只有 7,8,10-三苯基衍生物（2，方案 2）表现出强发光；7,8,9, 10-四苯基衍生物基本上是无荧光的（在固态下），而3,7,8,9-四苯基衍生物在固态下会发生大的红移。其他官能团（例如，酯、羧酸和卤化物）的引入导致绿色/黄色发射和/或溶解性问题。与其他衍生物一样，7,8,10-三苯基荧蒽通过 Knoevenagel/Diels-Alder 方法（方案 2）由苊醌、二苯丙酮和苯乙炔合成，仅使用乙醇 (EtOH) 和（可选）二甲苯作为溶剂；所有这些都是便宜且容易获得的。纯化不复杂 OMMUN IC A IO NS 例如，酯、羧酸和卤化物）导致绿色/黄色发射和/或溶解度问题。与其他衍生物一样，7,8,10-三苯基荧蒽通过 Knoevenagel/Diels-Alder 方法（方案 2）由苊醌、二苯丙酮和苯乙炔合成，仅使用乙醇 (EtOH) 和（可选）二甲苯作为溶剂；所有这些都是便宜且容易获得的。纯化不复杂 OMMUN IC A IO NS 例如，酯、羧酸和卤化物）导致绿色/黄色发射和/或溶解度问题。与其他衍生物一样，7,8,10-三苯基荧蒽通过 Knoevenagel/Diels-Alder 方法（方案 2）由苊醌、二苯丙酮和苯乙炔合成，仅使用乙醇 (EtOH) 和（可选）二甲苯作为溶剂；所有这些都是便宜且容易获得的。纯化不复杂 OMMUN IC A IO NS