Aromatic polyarenes sign inversion in magnetic circularly polarized luminescence through quantum modelling

The prerequisites for measuring magnetic circularly polarized luminescence from diamagnetic organic molecules are quite stringent and very few examples are disseminated in literature. In this context, a closely-lying and non-parallel polarized level relative to the emitting one, facilitates polycyclic aromatic hydrocarbons to exhibit MCPL spectra with peculiar properties. The lack of computational investigation in MCPL granted us the opportunity to grasp new findings by means an ad hoc theoretical modelling. A meticolous computational sequence proclaimed the TD-DFT/PBE/DZP as the best ab initio algorithm to capture the MCPL spectral profile of pyrene and phenanthrene derivatives. Adapting the Michl scheme for the emissive pathway, we democratized how the electron withdrawing/donating groups and their position on the aromatic system establish the MCPL band sign. Our in silico paradigm can prospectively cover a wide range of UV–visible π-fused luminophores, assisting chemists in a rational and diagostic design of carbon-based tunable MCPL materials.