CPL of complex molecular systems: achievements, failures, precautions and perspectives

Circularly polarized luminescence (CPL) is a relatively old technique, which has been revamped by recent success.1-3 Its recent widespread use has been made possible due to three facts: novel design of experimental apparatuses, computational advances and availability of luminescent systems, which are interesting for imaging and material science. The most studied complex luminescent systems encompass organometallic complexes and polymers, the latter ones being conjugated or presenting delocalized electron systems. We report CPL of transition metal complexes (Ir, Pt and U): and of molecular systems entrapping metals. The interpretation and use of CPL data is mainly qualitative, sometimes due to the fact that one is observing phosphorence effects, which still await quantitative evaluation by DFT calculations4. However the information gathered from the CPL spectra is interesting and complementary to the information from CD. CPL of polymers will also be presented in this note, with special regards to two types of polymers, namely polythiophene-based polymers (PT) and specially treated polystyrene polymers (PS) treated with chiral guests5. Among the first systems one notices that inherently chiral PT systems (either in the form of open closed oligomers)6 exhibit larger CPL than linear PT systems with chiral pendant groups.7