Extended Quinolizinium-Fused Corannulene Derivatives: Synthesis and Properties

Lin Huang; Qing Wang; Peng Fu; Yuzhu Sun; Jun Xu; Duncan L Browne; Jianhui Huang

doi:10.1021/jacsau.4c00105

Extended Quinolizinium-Fused Corannulene Derivatives: Synthesis and Properties

JACS Au. 2024 Mar 27;4(4):1623-1631. doi: 10.1021/jacsau.4c00105. eCollection 2024 Apr 22.

Authors

Lin Huang^{1

2

3}, Qing Wang^{1

4}, Peng Fu^{1

2

3}, Yuzhu Sun^{1

2

3}, Jun Xu¹, Duncan L Browne⁵, Jianhui Huang^{1

2

3}

Affiliations

¹ School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P. R. China.
² Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, P. R. China.
³ Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P. R. China.
⁴ National Institute of Biological Sciences, Beijing, No. 7 Science Park Road, Zhongguancun Life Science Park, Beijing 102206, China.
⁵ Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University College London (UCL), 29-39 Brunswick Square, Bloomsbury, London WC1N 1AX, U.K.

Abstract

Reported here is the design and synthesis of a novel class of extended quinolizinium-fused corannulene derivatives with curved geometry. These intriguing molecules were synthesized through a rationally designed synthetic strategy, utilizing double Skraup-Doebner-Von Miller quinoline synthesis and a rhodium-catalyzed C-H activation/annulation (CHAA) as the key steps. Single-crystal X-ray analysis revealed a bowl depth of 1.28-1.50 Å and a unique "windmill-like" shape packing of 12a(2PF₆^-) due to the curvature and incorporation of two aminium ions. All of the newly reported curved salts exhibit green to orange fluorescence with enhanced quantum yields (Φ_f = 9-13%) and improved dispersibility compared to the pristine corannulene (Φ_f = 1%). The reduced optical energy gap and lower energy frontier orbital found by doping extended corannulene systems with nitrogen cations was investigated by UV-vis, fluorescence, and theoretical calculations. Electrochemical measurements reveal a greater electron-accepting behavior compared with that of their pyridine analogues. The successful synthesis, isolation, and evaluation of these curved salts provide a fresh perspective and opportunity for the design of cationic nitrogen-doped curved aromatic hydrocarbon-based materials.