Over the past decades, increasing attention has been devoted to circularly polarized luminescence (CPL) up to becoming one of the most powerful and reliable spectroscopic tool for the analysis of a great variety of chemical systems. Resulting from the influence that chirality has over luminescent properties, the course of this technique is nowadays leaded by inorganic CPL emitters. However, it is known that pure organic samples with CPL activity may provide additional advantages (i.e. processability, lightness, transparency, etc.) and represent a hugely desirable option in several hot applications where toxicity factors are crucial (i.e., bioimaging). As a result, great efforts are currently being made for the development of these promising organic-based alternatives.
In this work, the study of CPL activity in organic free radicals emitters has been addressed for the first time, encouraged by the enhanced performance proved for magnetically active compounds in optics and optoelectronics. To this end, two triphenylmethyl (trityl) radical-based chlorinated derivatives, with propeller chirality, were considered, achieving an efficient chiral emission after the resolution of the racemic compounds.
Consequently, the pioneering approach here developed aims at laying the foundations for a new trend in optoelectronics and spintronics, where chiral, magnetic and luminescent properties can be used interchangeably in a single device. Thus, taking full advantage of the versatile nature of organic compounds will place us a step further in the miniaturization race of multifunctional nanomaterials.
Organic Free Radicals as Circularly Polarized Luminescence Emitters
Paula Mayorga-Burrezo, Vicente G. Jiménez, Davide Blasi, Imma Ratera, Araceli G. Campaña, Jaume Veciana
Angew. Chem. Int. Ed. 58, 16282 –16288, 2019
Figure: Molecular structures of optically and magnetically active enantiomers of one studied organic free radical