Fruitful interplay between theory and experiment in the design of circularly polarized luminescent materials

Abstract

Preliminary computations of NBN-benzo[f,g]tetracene/BINOL tethered structures (R)-/(S)-1 and (R)-/(S)-2 that suggest high oscillator strengths f and dissymmetry factors for CPL g_lum incited us to synthesize these compounds. The optical transitions within these structures have strong charge-transfer character from the benzotetracene-localized HOMOs to the LUMOs located at the BINOL. Large Stokes shifts of around 3500 cm⁻¹ are observed alongside quantum yields of 53–64%. The absorption and luminescence dissymmetry factors from ECD and CPL spectra were measured as g_abs = ±0.7 × 10⁻³ (1) and ±1.0 × 10⁻³ (2), and g_lum = ±0.5–0.6 × 10⁻³ (1) and ±1.6 × 10⁻³ (2), resulting in a CPL brightness (B_CPL) of 12.7–15.1 M⁻¹ cm⁻¹. This work shows that computational screening of chiroptical properties prior to synthesis is useful for identification of suitable materials.