Synthesis, structure, and electronic properties of a double hetero[4]helicene composed of two phenoselenazines

[Display omitted] We synthesized a novel double N,Se-hetero[4]helicene consisting of two phenoselenazines (1b) and discussed the impacts of chalcogen atoms on electronic and structural properties by comparing with a previously reported double N,S-hetero[4]helicene consisting of two phenothiazine (1a). The replacement of sulfur atoms of 1a with selenium atoms drastically increased the racemization barrier from 112.8 kJ mol−1 (1a) to 145.7 kJ mol−1 (1b) by maintaining its high electron donor property.