2018年度修士修了生の加藤裕貴君（Yuki Kato）と笹部久宏准教授の 3-ピリジルカルバゾール誘導体群の室温リン光挙動に関する「Room-Temperature Phosphorescence from a Series of 3-Pyridylcarbazole Derivatives」と題する論文が Wiley の Chemistry A European Journal (IF: 5.2) に受理されました！加藤、おめでとうございます！本研究は、山形大学 片桐研究室、理化学研究所 夫研究室との共同研究です。
Title: Room-Temperature Phosphorescence from a Series of 3-Pyridylcarbazole Derivatives
By Hisahiro Sasabe*, Yuki Kato, Yuichiro Watanabe, Tatsuya Ohsawa, Naoya Aizawa, Wataru Fujiwara, Yong-Jin Pu, Hiroshi Katagiri, Junji Kido*, Chem. Eur. J. 2019, accepted.
Abstract: Exploration of pure metal-free organic molecules that exhibit strong room-temperature phosphorescence (RTP) is an emerging research topic. In this regard, unveiling the design principles for an efficient RTP molecule is an essential but challenging task. A small molecule is an ideal platform to precisely understand the fundamental role of each functional component because the parent molecule can be easily derivatized. Here, the RTP behaviors of a series of 3-pyridylcarbazole derivatives are presented. Experimental studies in combination with theoretical calculations reveal the crucial role of the n orbital on the central pyridine ring in the dramatic enhancement of the intersystem crossing between the charge-transfer-excited singlet state and the locally excited triplet states. Single crystal X-ray crystallographic studies apparently indicate that both the pyridine ring and fluorine atom contribute to the enhancement of the RTP because of the restricted motion owing to weak CH–N and H–F hydrogen-bonding interactions. The single crystal of the fluorine-substituted derivative shows an ultra-long phosphorescent lifetime of 1.1 s and a phosphorescence quantum yield of 1.2%, while the bromine-substituted derivative exhibits phosphorescent lifetime of 0.15 s with a PLQY of 7.9%. We believe that this work provides a fundamental and universal guideline for the generation of pure organic molecules exhibiting strong RTP.
