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

Hai-Cheng Liu; Kaidong Ruan; Kexin Ma; Jiawei Fei; Yu-Mei Lin; Haiping Xia

doi:10.1038/s41467-023-41250-5

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

Nat Commun. 2023 Sep 11;14(1):5583. doi: 10.1038/s41467-023-41250-5.

Authors

Hai-Cheng Liu^#¹, Kaidong Ruan^#¹, Kexin Ma¹, Jiawei Fei¹, Yu-Mei Lin², Haiping Xia^{3

4}

Affiliations

¹ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, Fujian, China.
² State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, Fujian, China. linyum@xmu.edu.cn.
³ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, Fujian, China. hpxia@xmu.edu.cn.
⁴ Department of Chemistry, Shenzhen Grubbs Institute, Southern University of Science and Technology, 518055, Shenzhen, China. hpxia@xmu.edu.cn.

^# Contributed equally.

Abstract

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 ⁿBu₄NF, 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.