Synfacts 2017; 13(06): 0589
DOI: 10.1055/s-0036-1590291
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart · New York

Fluorescent, CPL-Active Aza[7]helicenes in Two Steps

Timothy M. Swager
Kosuke Yoshinaga
Otani T. * Tsuyuki A. Iwachi T. Someya S. Tateno K. Kawai H. Saito T. Kanyiva KS. Shibata T. * Waseda University, Tokyo, National Institute of Technology Anan College, Tokushima and Tokyo University of Science, Japan
Facile Two-Step Synthesis of 1,10-Phenanthroline-Derived Polyaza[7]helicenes with High Fluorescence and CPL Efficiency.

Angew. Chem. Int. Ed. 2017;
56: 3906-3910
Further Information

Publication History

Publication Date:
16 May 2017 (online)



Helicenes are molecules comprised of ortho-fused aromatic rings. They have potential applications in circularly polarized luminescence (CPL) emitting materials because some helicenes show high CPL activities. However, the fluorescence quantum yields of helicenes are generally low because the inherent curved π-systems promote rapid intersystem crossing from the singlet to the triplet states. Herein, Shibata and co-workers report a series of aza[7]helicenes that possess both high fluorescence and CPL activity, which make these molecules an appealing CPL-emitting material.



The authors report a facile two-step synthesis of aza[7]helicenes. The quantum yield of 1a (0.39) was comparable to the highest value among reported [7]helicenes (0.40). The addition of acid enhanced the quantum yield of 1a to 0.80. Although the value of the luminescence dissymmetry ratio g lum of 1a decreases slightly upon addition of acid (0.009 at 473 nm to 0.008 at 514 nm), this molecule remains an attractive CPL-emitting material. Single-crystal X-ray analysis and DFT calculations on 1a were also conducted.