Dihydropyrazine-embedded macrocycles behave like supersized cycloalkanes

Researchers in China have synthesised a series of molecules that resemble supersized versions of cyclobutane, cyclopentane and cyclohexane.

Cycloalkanes adopt puckered conformations to help relieve the strain caused when sp³-hybridised carbon atoms are forced into a ring and deviate from the ideal tetrahedral geometry. While these geometric quirks make cycloalkanes intriguing, studying the dynamics of their conformations has long posed experimental challenges.

The polygonal macrocycles created by Zhaohui Wang and co-workers at the East China University of Science and Technology may offer a new way to unpick the conformational dynamics of cyclobutene, cyclopentane and cyclohexane. Their molecules feature four, five or six dipyrene-fused dihydropyrazine corners, which introduce flexibility and allow the rings to adopt low-energy conformations similar to those of classic cycloalkanes.