Structures and Properties of Axially Chiral (2E,4E,6Z,8Z)-Nona-2,4,6,8-Tetraenoate Derivatives Highly Substituted by Aryl Groups.

Unprecedented (2E,4E,6Z,8Z)-nona-2,4,6,8-tetraenoate derivatives highly substituted by aryl groups have been synthesized by the reaction of rhodium complexes having aryl-substituted hexa-1,3,5-trienyl ligands with acrylates. These compounds have potential axial chirality, and their enantiomers are isolable by the chiral HPLC technique. Although the racemization barrier of isolated enantiomers was not high, it was found that a cyclic dimer synthesized by head-to-tail transesterification of a modified analog has quite a stable axial chirality even at a high temperature. From a structural analogy with tetraphenylethene, those compounds are emissive in the solid state, and the chiral cyclic dimer exhibits solid-state circularly polarized luminescence (CPL) activity.