Chiral memory via chiral amplification and selective depolymerization of porphyrin aggregates

J Am Chem Soc. 2010 Dec 1;132(47):16753-5. doi: 10.1021/ja1077602. Epub 2010 Nov 5.

Abstract

Chiral memory at the supramolecular level is obtained via a new approach using chiral Zn porphrins and achiral Cu porphyrins. In a "sergeant-and-soldiers" experiment, the Zn "sergeant" transfers its own chirality to Cu "soldiers" and, after chiral amplification, the "sergeant" is removed from the coaggregates by axial ligation with a Lewis base. After this extraction, the preferred helicity observed for the aggregates containing achiral Cu porphyrins reveals a chiral memory effect that is stable and can be erased and partially restored upon subsequent heating and cooling.