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

SignificanceWe first observed a transient chirality inversion on a simple unimolecular platform during the racemization of a chiral helical complex [LCo], i.e., the helicity changed from -rich (right-handed) to -rich (left-handed), which then racemized to a / equimolar mixture in spite of the absence of a reagent that could induce the 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, the 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.