Circularly Polarized Luminescence of Some [2]Paracyclo[2](5,8)quinoliphane Derivatives with Planar and Central Chirality

With the aim of finding and characterizing new simple organic molecules (SOM) generating circularly polarized luminescence (CPL), we test here nine [2]paracyclo[2](5,8)-quinoliphane derivatives, whose circular dichroism (CD) spectra were previously measured at short wavelengths in a study encompassing also OR and VCD (CD in the IR). Completion of the CD spectra is carried out with attention paid to weaker and longer wavelength features. The observed signs of the CPL spectra are compared to the signs of the CD band at the longest wavelength and are found coincident except in two cases. The magnitudes of dissymmetry ratios g in luminescence are of the order 10(-3), like the corresponding vertical bar g vertical bar values for the absorption case. TD-DFT calculations for the two simplest cases provide details on the molecular orbitals involved in the transitions responsible for the observed signals of these molecules. The calculations allow us to provide also a first explanation of the two observed behaviors of the vertical bar g(lum)vertical bar/vertical bar g(abs)vertical bar ratios.

Automated summary

Testing nine [2]paracyclo[2](5,8)-quinoliphane derivatives to find new simple organic molecules generating circularly polarized luminescence (CPL), the study observes asymmetry ratios g of the order 10^(-3) in luminescence, similar to the absorption case. TD-DFT calculations provide insight into the molecular orbitals responsible for transitions in the observed signals of these molecules, explaining the behaviors of the |g(lum)|/|g(abs)| ratios.