Chemistry Letters, Vol.42, No.7, 706-708, 2013
Oxidative Conversion of Tetraaryldihydrodibenzothiepins into Elemental Sulfur and Stable Cationic Dyes Accompanied by Dual UV-vis and CD Spectral Changes
Upon oxidation of the title heterocycles with dimethylamino groups, elemental sulfur is extruded to form dicationic dyes, which regenerate the heterocycles by the reaction with Na2S. The electrolysis of the heterocycles induces a drastic change in UV-vis spectrum exhibiting several isosbestic points. The bay-region substituents enhance configurational stability, so the optically pure heterocycle can be obtained in terms of helicity of one-handedness, and its chromism is accompanied by a large chiroptical response as detected by CD spectroscopy.