Stereodefined tetraarylethylenes: Synthesis and applications

Luminescent materials with efficient aggregate-state emissions are of growing interest due to their widespread applications in chemo-/biosensing and optoelectronic devices. Aggregation-induced emission (AIE) opens a new avenue for the applications of aggregate-state luminescent materials. Among the AIE luminogens (AIEgens), tetraarylethylenes (TAEs) are typical AIEgens with a simple molecule scaffold and could be utilized as a framework for further elaboration, enabling structure-property-function relationship studies and multi-functional applications. Since the existing approaches for the preparation of tetraarylethenes (TAEs) typically produce stereoisomeric mixtures, stereoselective synthesis of tetraarylethenes with desired geometry is a great challenge. In this review, we systematically compile the synthetic methodologies for the construction of TAEs in excellent regio- and stereoselectivities. The virtues and limitations of each methodology are discussed in detail as well. Meanwhile, the applications and the differences of properties between TAEs stereoisomers are introduced.