Effects of Ring Strain on Molecular Dynamics of Sterically Hindered 4,7‐Phenanthroline Unit

The Povarov reaction is a well‐known multicomponent reaction for the synthesis of quinoline derivatives from anilines, arylaldehydes, and dienophiles such as electron‐rich alkenes and alkynes. In this study, a sterically hindered 1,10‐diphenyl‐4,7‐phenanthroline derivative is synthesized via the Povarov reaction and incorporated into a cyclic conjugated structure to evaluate the effects of ring strain on the molecular dynamics of the 4,7‐phenanthroline moieties. The phenanthroline derivative is converted into a cyclic trimer, [3]McPhen , via a gold (Au) macrocyclic complex. The rate of rotation of the phenyl groups in [3]McPhen is found to be faster than that in the model compound without ring strain. Density functional theory calculations suggest that the ring strain of [3]McPhen causes a favorable orientation of the phenyl groups for rotation. This research offers valuable insights into the influence of ring strain on the dynamics of the molecular components.