Theoretical study on the gas and solution phase enthalpies, free energies, and equilibrium constants for the isomerization of 1.1paracyclophane derivatives as potential molecular switches

摘要

Theoretical studies were conducted on the predicted gas and solution phase thermodynamic properties for isomerization of various [1.1]paracyclophane derivatives to their corresponding transannular[4+4] adducts at representative levels of density functional and composite method theory. Calculations suggest the [1.1]paracyclophane to transannular[4+4] adduct isomerizations are not likely amenable to thermodynamic solvent tuning for the methylene, ether, and thioether bridged derivatives using a broad range of nonpolar and polar aprotic and polar protic implicit solvation models, but may be receptive towards solvent tuning for the amine bridged analogs. Varying the nature of the cyclophanic bridging atoms and the electron withdrawing/releasing character of photochemically/thermally stable substituents on the [pi]-systems is predicted to facilitate substantial variation of the isomerization equilibria to a much greater degree than changing the solvent environment.