Modeling of a Rotaxane-based Molecular Device

Abstract

ABSTRACTA computational procedure is presented for investigating photo-induced switchable rotaxanes and demonstrated for a known system. This procedure starts with the generation of more than 104 chemically reasonable rotaxane conformations based on an empirical intramolecular potential energy function. Single-point energy calculations at the semi-empirical (AM1) level are carried out for each structure in the singlet (ground), triplet, and anionic doublet states. The structural features are assigned and then correlated with energy for each state. What emerges is a profile of the structure-energy relationship that captures the salient features of the system that endow it with device-like character. Full geometry optimization of a subset of co-conformations (∼1%) demonstrates that the procedure based on single-point calculations is sufficient to obtain a profile of the relationship of structural features to energy that is consistent with experiments, at greatly reduced computational cost.