Construction and Phosphorescence Behavior of S/Se-Heteroaromatics/Phenanthrene-Fused Hetero[9]helicenes

Three S/Se-hetero[9]helicenes were synthesized by an assembly strategy of two building blocks, phenanthrene and ternary fused S/Se-heteroaromatic ring, and characterized by single-crystal X-ray diffraction analysis. Their phosphorescence emission gave a long-lived lifetime at the millisecond level. In addition, the high configurational stability of enantiomer (+)-[9]BH-1a was observed without change under both the conditions of 300 °C in the solid state for 18 h and 200 °C in solution of 1,2-dichlorobenzene for 10 h.