Synthesis of metalla-dual-azulenes with fluoride ion recognition properties

• Published in: Nature communications Vol. 14; no. 1; pp. 5583 - 10
• Main Authors: Liu, Hai-Cheng, Ruan, Kaidong, Ma, Kexin, Fei, Jiawei, Lin, Yu-Mei, Xia, Haiping
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 11.09.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/131; 140/58; 639/638/263/406/910; 639/638/403/933; 639/638/911/406/910; Azulene; Chemical reactions; Fluorides; Humanities and Social Sciences; Metals; multidisciplinary; Organic chemistry; Photoelectricity; Recognition; Science; Science (multidisciplinary); Transition metals
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-41250-5

Azulene-based conjugated systems are of great interests due to their unusual structures and photophysical properties. Incorporation of a transition metal into azulene skeleton presents an intriguing opportunity to combine the d π - p π and p π - p π conjugated properties. No such metallaazulene skeleton however has been reported to date. Here, we describe our development of an efficient [5 + 2] annulation reaction to rapid construction of a unique metal-containing [5-5-7] scaffold, termed metalla-dual-azulene (MDA), which includes a metallaazulene and a metal-free organic azulene intertwined by sharing the tropylium motif. The two azulene motifs in MDA exhibit distinct reactivities. The azulene motif readily undergoes nucleophilic addition, leading to N-, O- and S-substituted cycloheptanetrienyl species. Demetalation of the metallaazulene moiety occurs when it reacts with n Bu 4 NF, which enables highly selective recognition of fluoride anion and a noticeable color change. The practical [5 + 2] annulation methodology, facile functional-group modification, high and selective fluoride detection make this new π-conjugated polycyclic system very suitable for potential applications in photoelectric and sensing materials. Azulene-based conjugated systems are of great interests due to their unusual structures and photophysical properties but incorporation of a transition metal into azulene skeleton presents remains elusive. Here, the authors describe an efficient [5 + 2] annulation reaction for the rapid construction of a metalla-dual-azulene.