Fig. 2: Summary of the mechanochemical model of the measured isomerization kinetics.
a, b E-SS(OMe)2 with compressive force acting on its methoxy C atoms reproduces the structures of the stiff stilbene moiety in the macrocycles. In (a) the underlying structural homology is illustrated by the correlation between the ArC-C = C-CAr torsion and the O…O distance in all conformations of the E macrocycles following the same correlation in force-coupled SS(OMe)2. In (b), the C…C and O…O distances in the conformers of the macrocycles are compared with the same distances in E-SS(OMe)2 as a function of the applied force. c Calculated ΔGǂ in the two diastereomeric series of the macrocycles are reproduced accurately using SS(OMe)2 coupled to a compressive potential with compliance of 2 and 0.3 Å/nN respectively. Maximum fE that a compressive potential can apply decreases with increasing compliance, resulting in force-dependent activation free energy of isomerization, ΔGǂ, terminating below 1 nN for compliances >2 Å/nN. d Force exerted on SS(OMe)2 by a compressive potential with a finite compliance decreases as the molecule progresses along the isomerization reaction path, resulting in lower ensemble-average force in the transition state, 〈fts〉, compared to that in the E isomer, 〈fE〉. The plotted data is tabulated in Supplementary Tables 6–8.
