Circularly polarized luminescence of molecular systems

Chiral emissive species can present the ability to emit left- and right-circularly polarized light with different intensities, giving rise to a circularly polarized luminescence (CPL). The interest in the design of new systems stems mainly from the application of CPL emitters in various scientific and technological fields, ranging from the fabrication of circularly polarized organic light emitting diodes (CP-OLEDs) to the development of analytical probes for the detection of small chiral molecules and biosubstrates. This first part of this work is focused on the investigation of new chiral Ln(III) complexes able to emit circularly polarized luminescence in the visible and near infrared (NIR) range of the electromagnetic spectrum. We present both homoleptic and heteroleptic complexes of a series of lanthanide ions bearing either chiral bis(oxazolinyl)pyridine ligands or diaminociclohexane (DACH) based ligands. In this context, we investigate one of the complexes as a CPL-based sensing tool for lactate in aqueous solution. In addition, we also discuss the design of enantiopure Eu(III) and Sm(III) cryptates and investigate their CPL activity. The second part concerns the study of the CPL activity of chiral organic molecules. In particular, we investigate enantiopure dimeric helicenes and present the first example of circularly polarized electrochemiluminescence (CP-ECL) of a purely organic compound, achieved using a fluorophore-appended macrocycle.