Magnetic Circularly Polarized Luminescence in the Photoexcited States of Racemic [n]Helicenes (n=3–5,7) in Tetrahydrofuran and Dimethyl Sulfoxide Solutions

This paper reports the first magnetic circularly polarized luminescence (MCPL) characteristics of racemic helicenes, including four unsubstituted [n]helicenes (n=3,4,5,7) and two [4]helicene derivatives bearing methoxy substituents, in tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO) solutions. The value of |gMCPL| was calculated to be of the order of 10−3 T−1 within 350–430 nm under the north‐up (N‐up) and south‐up (S‐up) Faraday geometries in an external magnetic field of 1.6 T. The [n]‐dependent MCPL signs were altered by the N‐up and S‐up geometries. Racemic [n]helicenes at the photoexcited state under 1.6 T reveals circular polarization in the order of 0.1 % T−1 at the room temperature. The magnetic circularly polarized luminescence sign can be inverted by choosing Faraday geometry and [n]‐number with/without methoxy groups.