Transient Induction of Chirality from an Activated Carboxylic Acid to a Zinc Complex

Enantiomerically pure activated carboxylic acids (ACAs), (R)- and (S)-2-cyano-2-phenylpropanoic acids, are exploited to program the induction of chirality onto a zinc metal complex over time. NMR analysis shows that binding of the enantiopure ACA conjugate base to the Zn²⁺ center breaks the symmetry of the complex and induces the formation of a single diastereoisomeric metal complex. Such a diastereoisomer is present only as long as the ACA is found in solution, and the ACA loading determines the time interval in which it persists in solution. At the end of the dissipative ACA cycle, no diastereoisomeric/enantiomeric excess is present anymore in the mixture. For the first time, a coordination process involving an ACA, more precisely its conjugate base, instead of an acid-base reaction, is exploited to drive a dissipative system.