Chiroptical properties of the ground and excited states of two thia-bridged triarylamine heterohelicenes

[Display omitted] •Chiroptical Spectra performed on Thia-bridged Triarylamino Heterohelicenes (TBTA-HELI).•TBTA-HELI are configurationally more stable than plain helicenes of the same size.•TBTA-HELI exhibit larger CPL than plain helicenes.•Excited states of TBTA-HELI are dissymmetric, while ground states are symmetric. Two thia-heterohelicenes of different length, namely a hetero [4]-helicene (1), and a hetero [6]-helicene (2) are studied by electronic circular dichroism (ECD), circularly polarized luminescence (CPL), vibrational circular dichroism (VCD) and optical rotation (OR). It is found that the ECD and VCD spectra are characteristically different from the corresponding spectra of the parent helicene molecules, indicative of the presence of hetero atoms. CPL spectra are discussed on the basis of DFT calculation results. The sign of the OR is different for the two thiaheterohelicenes and is correctly predicted by DFT calculations.