Acenes are linear molecules comprised of benzene rings. These rings are known for their resonance: a state in which their electrons are delocalized. Unlike other molecules, in which the electrons are associated with specific atoms and therefore restricted in space, the delocalized electrons are free to move throughout the molecule. The delocalization of electrons leads to the electrical semiconductivity of the molecule. Semiconductors are materials that conduct only under specific conditions. These materials (e.g. Silicon) are widely used in the electronics industry. Acenes can be either planar (2D) or twisted (3D). It is known that twisting affects the electronic and optical properties, however, measuring this effect is difficult as changing planarity results in a new molecular structure with modified properties.
In a new paper by Anjan Bedi from Ori Gidron’s lab, two types of acenes were connected by ‘molecular bridges’ of different lengths. Each bridge locked the molecule in a different twisting angle. This way, it was possible to monitor the effect of twisting on the electronic and optical properties. For example, as the twisting angle increased, the color changed and fluorescence dramatically decreased. In addition, the chirality of the molecule alternated.
Locking the molecular structures allowed the isolation of two mirror imaged molecules, called enantiomers. Each enantiomer rotates polarized light in opposite direction. The normalized value of rotation is called the anisotropy factor. These enantiomers exhibited high anisotropy factor and thermal stability. Molecules with high anisotropy factor are considered promising materials for the field of quantum computing and may also serve as sensors for biological entities.