Building on the semi-structural analysis above, we returned to the general symmetry properties of mechanically axially chiral molecules (Supplementary section 12.1). Whereas the components of catenane II and rotaxane IV have C1v point group symmetry, more generally mechanical axial stereochemistry will arise in catenanes whose rings have Cnv symmetry and rotaxanes whose axle has C1v symmetry. Such structures will tend to exhibit prochirality any single structural modification that does not lie on a symmetry plane will result in a chiral object (Supplementary section 12.2). As a direct consequence, although mechanically axially chiral molecules can always, in theory, adopt a highly symmetrical co-conformation (e.g. II and IV) that only expresses mechanical axial stereochemistry, if either ring is displaced from this arrangement the resulting structure contains both a mechanically axially chiral stereogenic unit and a co-conformational covalent stereogenic unit (e.g. III and V). These lower symmetry arrangements exist as pairs of co-conformational diastereomers and are an inherent property of mechanically axial chiral molecules (Supplementary section 12.3).