Sulfur‐Doped Quintuple [9]Helicene with Azacorannulene as Core. Issue 33 (4th July 2022) - Wu, Yin‐Fu
Abstract: Herein, a hetero(S, N)‐quintuple [9]helicene (SNQ9H ) molecule with an azacorannulene core was synthesized, currently representing the highest hetero‐helicene reported in the field of multiple [ n ]helicenes. X‐ray crystallography indicated that SNQ9H includes not only a propeller‐shaped conformer SNQ9H‐1, but also an unforeseen quasi‐propeller‐shaped conformer SNQ9H‐2 . Different conformers were observed for the first time in multiple [ n ≥9]helicenes, likely owing to the doping of heteroatomic sulfurs in the helical skeletons. Remarkably, the ratio of SNQ9H‐1 to SNQ9H‐2 can be regulated in situ by the reaction temperature. Experimental studies on the photophysical and redox properties of SNQ9H and theoretical calculations clearly demonstrated that the electronic structures of SNQ9H depend on their molecular conformations. The strategy of introducing heteroatomic sulfurs into the helical skeleton may be useful in constructing various conformers of higher multiple [ n ]helicenes in the future. Abstract : Two conformers of a novel quintuple [9]helicene with an azabuckybowl as the core were obtained by the deliberate introduction of sulfur heteroatoms into the helical skeleton. The structure–property relationship of different conformers was investigated through detailed experiment and theoretical calculations. The success of the sulfur‐doped strategy implies the potential of realizing higher multiple [ n ]helicenes with various conformers.