Simple organic molecules (SOM) based on bis(haloBODIPY) are shown to enable circularly polarized luminescence (CPL), giving rise to a new structural design for technologically valuable CPL-SOMs. The established design comprises together synthetic accessibility, labile helicity, possibility of reversing the handedness of the circularly polarized emission, and reactive functional groups, making it unique and attractive as advantageous platform for the development of smart CPL-SOMs.

This article aims to show the identity of “circularly polarized luminescent active simple organic molecules” as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented.

Several models, theoretical levels and computational methods, all based on the canonical variational transition state approximation, have been used to predict both the experimental activation energies (ΔE_exp^≠) and the experimental activation free energies (ΔG_exp^≠) for the hydrolysis of aryldiazonium ions. It is demonstrated that the computation of activation energies (ΔE^≠), instead of activation free energies (ΔG^≠), agrees better with the corresponding experimental data, showing that the employed computational methods do not afford reliable entropic contributions to the free energy barriers in the case of the studied reaction. However, the most fitted computations of ΔE^≠ were not able to clearly differentiate between the mechanisms proposed for this interesting reaction (S_N1, S_N2 and water cluster). In contrast, the use of the Marcus theory (hyperbolic-cosine equation) instead of the canonical variational transition state theory leads to excellent agreement between the in-water-computed activation energies (ΔE_wM^≠) and the corresponding ΔE_exp^≠ values for the S_N2 mechanism, but far beyond the limit of error for the S_N1 process. The validity of the Marcus theory for the studied S_N1 and S_N2 reactions is ensured by the fact that both reactions can be described as SET processes. On the other hand, apparently compelling evidence against the S_N2 mechanism, such as ¹³C KIEs and experimental observation of N₂ scrambling, are also discussed and alternative explanations are proposed.