A Computational Investigation of a Molecular Switch

We have developed and implemented a computational experiment that explores the behavior of a [2]catenane as a molecular switch. The experiment introduces mechanically interlocked molecules and discusses their potential as artificial molecular machines. The relaxation rate and lifetime, as well as the ratio of the ground state and the metastable state configurations, are calculated in the gas phase as well as solvents of varying polarity using semiempirical quantum chemical calculations. The π–π donor–acceptor interactions between the two macrocycles comprising the catenane are probed via Hartree–Fock calculations of the frontier molecular orbitals. It is shown that NMR calculations may be employed to aid in the identification of various chemical species. The graphical user interface of the open-source molecular editor Avogadro was employed to visualize the crystal structure of the catenane, followed by quantum chemical calculations using the WebMO graphical interface.