As a second representative test case, we studied the formamidinium [2]Rotaxane recently reported by Borodin et al. (see Fig. ). This rotaxane consists of an N,N'-disubstituted formamidinium ion and the flexible 24-crown-8 (24C8) ether (Fig. ), and it is part of a seminal work describing the self-assembly of stimuli-responsive [2]rotaxanes, using the dynamic covalent reaction amidinium exchange. This system, referred to hereinafter as 2, allows us to test our methods on a relevant case in which both the axle and the macrocycle are flexible.