Synthesis, crystal structure, Hirshfeld surface analysis and DFT study of the 1,1'-(buta-1,3-diyne-1,4-di-yl)bis-(cyclo-hexan-1-ol).

The title compound, C 16 H 22 O 2 , was synthesized in order to obtain its guest-free form because 'wheel-and-axle'-shaped mol-ecules tend to crystallize from solutions as solvates or host-guest mol-ecules. It crystallizes in the monoclinic space group P 2/ c with two crystallographically non-equivalent mol-ecules, one situated on an inversion center and the other on a twofold axis. The rod-like 1,3-diyne fragments have the usual linear geometry. In the crystal, O-H ⋯ O bonds form eight-membered rings of the R 4 4 (8) type, linking mol-ecules into layers. The Hirshfeld surface analysis indicates that the largest con-tributions are from inter-molecular H⋯H ( ca 71%) and H⋯C/C⋯H ( ca 19%) contacts. The energies of the frontier mol-ecular orbitals were determined by DFT calculations at the B3LYP/def2-TZVP level of theory.