Solvent and Temperature Effects on Dynamics and Chiroptical Properties of Propeller Chirality and Toroidal Interaction of Hexaarylbenzenes
Tomoyo Kosaka, Satono Iwai, Yoshihisa Inoue, Toshiyuki Moriuchi, Tadashi Mori
The Journal of Physical Chemistry A
Because of the unique interaction of radial aromatic blades, propeller-shaped hexaarylbenzenes (HABs) attract much research interest and find various practical applications. By introducing a small point-chiral group at the tip of aromatic blade(s), HAB becomes propeller-chiral to exhibit strong Cotton effects. Due to the dynamic nature of propeller chirality, the chiroptical properties of HAB critically responded to minute changes in environment. Using a series of chiral HABs with one to six (R)-1-methylpropyloxy substituent(s) introduced at the blade tip, we elucidated how the smallest chiral auxiliary at the HAB periphery progressively and cooperatively boost the overall chiroptical properties, and also how subtle changes in temperature and solvent structure affect the propeller dynamics and thus the chiroptical responses. The unique features of propeller-chiral HABs further enabled us to switch on/off their circularly polarized luminescence.
Circular dichroism, Stereochemistry, Chemical stability, Thermal stability, Thermodynamics, Materials