Cold Snapshot of a Molecular Rotary Motor Captured by High-Resolution Rotational Spectroscopy

Angew Chem Int Ed Engl. 2017 Sep 4;56(37):11209-11212. doi: 10.1002/anie.201704221. Epub 2017 Jun 20.


We present the first high-resolution rotational spectrum of an artificial molecular rotary motor. By combining chirped-pulse Fourier transform microwave spectroscopy and supersonic expansions, we captured the vibronic ground-state conformation of a second-generation motor based on chiral, overcrowded alkenes. The rotational constants were accurately determined by fitting more than 200 rotational transitions in the 2-4 GHz frequency range. Evidence for dissociation products allowed for the unambiguous identification and characterization of the isolated motor components. Experiment and complementary quantum-chemical calculations provide accurate geometrical parameters for the C27 H20 molecular motor, the largest molecule investigated by high-resolution microwave spectroscopy to date.

Keywords: high-resolution spectroscopy; large molecules; microwave spectroscopy; molecular motors; structure elucidation.

Publication types

  • Research Support, Non-U.S. Gov't