Circularly Polarized Luminescence of [6]Helicenes through Excited- State Intramolecular Proton Transfer

Abstract

We present the concept of combining circularly polarized luminescence (CPL) and excited-state intramolecular proton transfer (ESIPT) features into a single molecule as a strategy to generate high-performance ESIPT-based CPL materials. For this purpose, a [6]helicene bearing two ESIPT structural units was synthesized using a double Suzuki-Miyaura reaction and a double C(sp(2))-H hydroxylation approach. The photophysical properties of the doubly hydroxylated [6]helicene were studied in parallel with a non-hydroxylated [6]helicene control compound, revealing that the presence of a chiral [6]helicene unit results in a strong CPL response and the presence of the ESIPT units in a considerable red shift. The red-shifted emission along with the outstanding g(lum) (approximate to 10(-2)) and a large Stokes shift makes the doubly hydroxylated [6]helicene a promising candidate for use in optoelectronics.