A Molecule like Three-bladed Gear

Triptycene (1) is a three-bladed molecule synthesized by P. D. Bartlett et al. in 1942. The structure of 1 is rigid, 120° orienting, and three-pronged, so it was named after "the triptych of antiquity".^1,2)
1 has been investigated as a part of molecular machines because of its unique structure. For example, a molecular bevel gear which has a cyclopropenium ring with three triptycenes is synthesized by using of 9-bromotriptycene (2).³⁾
Furthermore, it has been reported that the synthesis of the 9-triptycylselenol kinetically stabilized by a sterically-crowded triptycene component, followed by the reaction of 9-triptycylselenol with a palladium complex resulted in the production of the five-membered selenapalladacycle.^4,5)