Compound 1 and 2 were simulated in vacuo. This was done to sample the full attainable conformational space without mediation of intercalated apolar solvent molecules (such as CHCl 3 or C 2 H 2 Cl 2 ) experimentally favoring the symmetric forms. For both 1 and 2, simulations were hence conducted on a single macrocyclic molecule at constant temperature using a Nosé thermostat. The HREM simulations for compound 1 and 2 were done using a protocol with scaling of all intramolecular interactions (except for stretching and bending) with s min = 0.1 corresponding to a maximum "temperature" of 3000 K. We used eight or twelve states/replicas depending on the system, with scaling protocol given by s k = s