Controlling the Emissive, Chiroptical, and Electrochemical Properties of Double [7] Helicenes through Embedded Aromatic Rings. Issue 58 (17th August 2022)

• Record Type: Journal Article
• Authors: Hong, Juan; Xiao, Xuxian; Liu, Haoliang; Dmitrieva, Evgenia; Popov, Alexey A.; Yu, Zidong; Li, Ming‐De; Ohto, Tatsuhiko; Liu, Jun; Narita, Akimitsu; Liu, Pengcai; Tada, Hirokazu; Cao, Xiao‐Yu; Wang, Xiao‐Ye; Zou, Yingping; Müllen, Klaus; Hu, Yunbin
• Is Part Of: Chemistry. Volume 28:Issue 58(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-17
• Subjects: chiroptical properties -- helicenes -- photophysics -- radical cation -- triazole; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202202243
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We present here the synthesis and in‐depth physicochemical characterization of a double hetero[7]helicene fused with four triazole rings at both helical ends. The comparison of this triazole‐fused double helicene with the previously reported all‐carbon and thiadiazole‐fused analogs revealed the huge impact of the embedded aromatic rings on the photophysical features. The small structural variation of the terminal rings from thiadiazole to triazole caused a dramatic change of the photoluminescence quantum yields (PLQYs) from <1 % to 96 %, while the replacement of the terminal benzene rings with triazole rings induced a tenfold enhancement of the circularly polarized luminescence dissymmetry factor. These observations were well corroborated with transient absorption analysis and/or theoretic calculations. In addition, the triazole‐fused double helicene exhibited ambipolar redox behavior, enabling the generation of radical cation and anion species by electrochemical and chemical methods and showing its potential for spin‐related applications. Abstract : Controlling the photophysics of double helicenes is facilely achieved by variation of the terminal aromatic rings. Compared to the thiadiazole‐fused and all‐carbon analogs, triazole‐fused double helicene shows significantly enhanced emission with near‐unity quantum yield, and high circularly polarized luminescence brightness of up to 30.1 M −1 cm −1, as well as excellent ambipolar redox behavior.