Transient chirality inversion during racemization of a helical cobalt(III) complex

Significance We first observed a transient chirality inversion on a simple unimolecular platform during the racemization of a chiral helical complex [LCo3 A 6 ]3+ , i.e., the helicity changed fromP -rich (right-handed) toM -rich (left-handed), which then racemized to aP /M equimolar mixture in spite of the absence of a reagent that could induce theM helix. This transient chirality inversion was observed only in the forward reaction, whereas the reverse reaction showed a simple monotonic change with an induction time. Consequently, theM helicity appeared only in the forward reaction. These forward and reverse reactions constitute a hysteretic cycle. Compounds showing such unique time responses would be useful for developing time-programmable switchable materials that can control the physical/chemical properties in a time-dependent manner.