Synthesis of Chiral Spiro <i>π</i>-Conjugated Compounds and Their Optical Properties

Spiro π-conjugated compounds, consisting of two orthogonally arranged π-conjugated frameworks, exhibit unique optical and electronic properties, along with high solubility and thermal stability. Owing to these features, they have been extensively studied as fundamental scaffolds for functional organic materials. Depending on the substitution pattern, spiro π-conjugated compounds can also be chiral, and various chiral spiro π-conjugated compounds have been synthesized to date. However, studies focusing on their chirality remain rather limited. Recently, our group has developed a series of chiral spiro π-conjugated compounds, in which heteroles and/or donor-acceptor structures are incorporated to tune the optical properties. This article describes the synthesis of these chiral spiro π-conjugated compounds and the elucidation of their optical properties, including circularly polarized luminescence (CPL) characteristics. These systematic studies provide new insights into the structure-property relationships of chiral spiro π-conjugated compounds.