Carbohelicenes generally incorporate a helical, distorted, conjugated, polyaromatic system with ortho-fused benzenoid rings, which is a fundamental molecular characteristic of this class of compounds. They have been described as "molecules in distress" due to their distortion. The generation of a chiral helicity in helicenes was observed because of a severe intramolecular steric strain. Helicity is a molecular necessity in the higher series of carbohelicenes, when at some point, a helical pitch occurs when a second coil is formed. The most interesting properties resulting from such molecular distortion are the very high chiroptical and circular dichroism values. For instance, the resolution of some helicene racemates by "hand picking" of a few homochiral single enantiomeric crystals allowed for a measurement of their optical rotation. Due to that intrinsic chirality spanned over a large polyaromatic template, preliminary results clearly established the efficiency of carbohelicenes to induce asymmetry and chirality in organic synthesis and in supramolecular chemistry. Additionally, they have some potential uses in several fields: materials science, nanoscience, chemical biology and supramolecular chemistry. It has encouraged many attempts to develop new asymmetric syntheses of carbohelicenes, as well as some chiral separations of enantiomers and diastereoisomers. This review is thus dedicated to carbohelicene chirality. It gathered a substantial collection of data, and a comprehensive review on the preparations of enantioenriched helicenes, either from an asymmetric synthesis or from a chiral separation. Utilizations of non-racemic helicenes and their applications will be treated in the following review (Part 3), and will not be the subject of this manuscript.

A molecule consisting of a hexathio-benzene core and peripheral tolyl substituents exhibits outstanding phosphorescence properties in some environments favoring rigidity, in the solid state and in a solid matrix at 77 K, while no luminescence is recorded in solution at room temperature. This peculiar behavior is attributed to the restriction of bond rotation and conformational mobility of the tolylthio substituents, which slows down the non-radiative deactivation processes of the phosphorescent excited state. The solid material (powder) shows a very high phosphorescence quantum yield (80%), which, to the best of our knowledge, is the highest reported value for organic molecules. The photophysical investigation was accompanied by a detailed computational study disclosing the role of CH–π interactions. This molecule has been exploited toward luminescent organic nanocrystals and light-emitting diodes with a fully solution processable technology

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