Sign dependence of MCPL spectra on type and position of substituent groups of pyrene and phenanthrene derivatives

Diamagnetic achiral pyrene and phenanthrene derivatives substituted with electron-donating hydroxyl/methoxy groups and electron-withdrawing carboxylic acid groups exhibited clear magnetic circularly polarised luminescence (MCPL) spectra at 360-460 nm in dilute solvents upon the application of N-up and S-up Faraday geometries under an external magnetic field of 1.6 T. Their MCPL signs were also susceptible upon application of the same Faraday geometry. Achiral pyrene and phenanthrene derivatives with electron-donating hydroxyl/methoxy and electron-withdrawing carboxylic acid groups exhibited magnetic circularly polarised luminescence at 360-410 nm in dilute solution under N-up and S-up Faraday geometries at 1.6 T.