Circularly Polarized Luminescence from Chiral Spiro Molecules: Synthesis and Optical Properties of 10,10′-Spirobi(indeno[1,2‑b][1]benzothiophene) Derivatives

Chiral spiro polycyclic aromatic compounds with thiophene and/or thiophene S,S-dioxide units were synthesized as a new family of circularly polarized luminescence (CPL) materials. Oxidation of the thiophene unit to its S,S-dioxide provided significant changes in photophysical properties such as much higher fluorescence quantum yield and positive solvatochromism in photoluminescence spectra. Density functional theory calculations qualitatively demonstrated the observed absorption properties. The prepared chiral spiro compounds exhibit intense CPL signals with a relatively large dissymmetry factor for small organic molecules.