Sign inversion of magnetic circularly polarized luminescence in Iridium(iii) complexes bearing achiral ligands.

Optically inactive, paramagnetic Ir(iii)(ppy) and Ir(iii)(ppy)(acac) (ppy: 2-phenylpyridinate and acac: acetylacetonate) showed nearly mirror-symmetric magnetic circularly polarised luminescence (MCPL) spectra in dilute dichloromethane and dimethyl sulfoxide under N-up and S-up geometries in a 1.6-T magnetic field. However, the MCPL signs of Ir(iii)(ppy) and Ir(iii)(ppy)(acac) under the same N-up (or S-up) Faraday geometry were opposite to each other when one ppy was replaced with an acac.