Tether-directed regioselective synthesis of new cis-2ʹ azafullerene bisadducts

Embarking into unexplored realms beyond the C1 equatorial-face and C1 trans-4' regioisomers, this study delves into the synthesis of cis-2ʹ C59N bisadducts. The synthesis involves a two-step process. Firstly, a Mannich-type reaction between bisazafullerene (C59N)2 and a tether yields a monoadduct. Further Bingel-Hirsch cyclopropanation results in the formation of the desired cis-2ʹ C59N bisadducts. Comprehensive spectroscopic techniques, including polarimetry and X-ray crystallography, confirm the absolute configuration (f,sclockwise or f,santiclockwise) of the enantiomerically pure cis-2ʹ C59N bisadducts. Circular dichroism measurements revealed the extremely high chiroptical activity of these inherently chiral bisadducts. Evaluation of their optoelectronic properties through Vis-NIR absorption, PL emission, and cyclic voltammetry techniques reveals distinctive bandgap and NIR emission, ranging from 1.31 to 1.81 eV and 700 to 1108 nm, respectively, showcasing promising potential for applications in energy conversion.