Molecular Shuttles. A Computational Study (MM and MD) on the Translational Isomerism in Some [2]Rotaxanes

Abstract

The translational isomerism experimentally observed in some [2]rotaxanes has been studied and modeled by means of molecular mechanics and molecular dynamics calculations using Allinger's MM3 force field and MM3*, the implemented version of MM3 for MacroModel. A reasonable agreement between the computed and experimental values for translational barriers has been obtained. Translational barriers are due to nonbonded interactions and can be tuned by introducing alkyl groups in the polyether chain.

Computational Studies on Two Supramolecular Structures: Cyclodextrins and Rotaxanes

“…The development of computational approaches for studying these interesting systems will certainly open new directions of interest and research. We were able to show recently that the AMBER* force field reproduces short C-H···O contacts in [2]rotaxanes [84]. Besides, we reported also a new six-site solvent model for acetonitrile [85] (the major solvent used in the rotaxane chemistry) based on the AMBER scheme.…”

Structural, energetic, and dynamical properties of rotaxanes constituted of α-cyclodextrins and an azobenzene chain

“…We however noted the work of Jaime and collaborators who investigated the effect of implicit acetonitrile solvent [40] and explicit water and acetonitrile solvent [41,42] on a rotaxane structure composed by cyclobis-(paraquat-p-phenylene) macrocycle complexed to polymeric chain containing aromatic units. The force field MM3 was used for the investigation with GB/SA implicit solvation and AMBER was selected for explicit solvation studies.…”

DFT and local MP2 study of switching process in a pH controllable molecular “shuttle”

“…Using the anthracene stopper, it is possible to monitor the switching process by means of an electrochemical and photophysical techniques due to its absorption, luminescence, and redox properties. The switching process in molecular “shuttles” has been a subject of a number molecular mechanic studies 3–6. However, to the best of our knowledge, there is only one quantum mechanic (semiempirical) study 7 of a pH‐switchable 2 rotaxane‐based molecular “shuttle” with two 3,5‐(di‐ter‐butyl)phenyl stoppers, which is related to the size of the system involved in quantum mechanical treatment.…”