Stereoisomerization during Molecular Packing

Isomerization is an essential chemical process that often evokes dramatic change of chemical, physical, or biological properties. For a long time, isomerization has been known as a transformation that is induced by certain external energy such as light, heat, or mechanical force. Herein, a new isomerization phenomenon is described, which does not require external energy but simply occurs during molecular packing. The proposed isomerization is demonstrated by a series of symmetric donor-acceptor-donor (D-A-D) molecules, the donor of which may adopt two different stereoisomeric forms. Based on the evidence of the asymmetric isomers in crystals, the occurrence of isomerization during molecular packing is proved. Moreover, the unique asymmetric geometry in the solid state favors the restriction of intramolecular motion, resulting in highly efficient organic solids with quantum yields approaching unity.

Automated summary

The article describes a new isomerization phenomenon that occurs during molecular packing without the need for external energy. Evidence of asymmetric isomers in crystals proves the occurrence of isomerization during molecular packing, leading to highly efficient organic solids with a unique asymmetric geometry that restricts intramolecular motion.