Division of Organic Chemistry, Group of Functional Materials Synthesis, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Łódź, Poland.
Faculty of Mathematics and Natural Sciences, Institute of Chemistry, Health and Food Sciences, Department of Materials & Structural Chemistry, Jan Długosz University in Częstochowa, Armii Krajowej 13/15, 42-201, Częstochowa, Poland.
Chemistry. 2019 Nov 7;25(62):14148-14161. doi: 10.1002/chem.201903027. Epub 2019 Oct 14.
The highly substituted mono-aryl/alkylthio-(hetero)acenes prepared in this study have been found to be thermally more stable (T =331-354 °C) than the known di-aryl/alkylthio-substituted acenes by an average of 25 °C. They are also much more photostable at 254 and 365 nm (in both argon and air) than the parent anthracene and other reported anthracenes. The most photostable aryl/alkylthio-anthracenes at 254 nm were found to be 60-70 (in air) and 130 (in argon) times more stable in solution than the unsubstituted anthracene, and much more stable than known EDG/EWG-substituted anthracenes (EDG=electron-donating group, EWG=electron-withdrawing group) with an extended aromatic core. Furthermore, the acenes showed significantly higher photostability at 365 nm in both air and argon. The anthracenes were obtained by the novel thio-Friedel-Crafts/Bradsher cyclization reaction of hitherto unknown o-(1,3-dithian-2-yl)arylmethyl thioethers. The developed approach provides a general access to mono-aryl/alkylthio-substituted (hetero)acene frameworks containing at least three fused (hetero)aromatic rings. The characteristic feature of this approach, which leads to highly substituted acenes, is that the substituents, unlike in other methods, may be introduced at an early stage of the synthesis. DFT and TD-DFT calculations confirmed the stabilizing role of the aryl/alkylthio substituent in the mono-aryl/alkylthio-substituted anthracenes, which are the most stable anthracenes prepared to date. Their high photostability is mainly due to the quenching of singlet oxygen by the acene and the quenching of the acene S state by molecular oxygen.
本研究制备的高取代单芳基/烷基硫-(杂)薁类化合物比已知的二芳基/烷基硫取代薁类化合物热稳定性更高（T=331-354°C），平均高出 25°C。与母体蒽和其他报道的蒽相比，它们在 254 和 365nm 下（在氩气和空气中）也具有更高的光稳定性。在 254nm 下，最稳定的芳基/烷基硫-蒽类化合物在空气中的稳定性比未取代的蒽高 60-70 倍（在空气中），在氩气中高 130 倍（在氩气中），比具有扩展芳环的已知 EDG/EWG 取代蒽类化合物稳定得多（EDG=供电子基团，EWG=吸电子基团）。此外，在空气和氩气中，薁类化合物在 365nm 下的光稳定性也显著提高。蒽类化合物是通过 hitherto unknown o-(1,3-dithian-2-yl)arylmethyl thioethers 的新型硫-Friedel-Crafts/Bradsher 环化反应得到的。所开发的方法提供了一种通用的方法，可以获得至少包含三个稠合（杂）芳环的单芳基/烷基硫取代（杂）薁类化合物。该方法的特点是，与其他方法不同，取代基可以在合成的早期阶段引入。DFT 和 TD-DFT 计算证实了芳基/烷基硫取代基在单芳基/烷基硫取代蒽类化合物中的稳定作用，这些蒽类化合物是迄今为止制备的最稳定的蒽类化合物。它们具有高的光稳定性主要是由于蒽类化合物猝灭单线态氧和分子氧猝灭蒽类化合物 S 态。
