Fig. 2

Optical features of ^Th4 COT _Saddle and ^Th6 CDH _Screw . a, b, Schematic structures of the enantiomers of ^Th4 COT _Saddle (a) and ^Th6 CDH _Screw (b). c, d, Electronic absorption spectra of ^Th4 COT _Saddle (c) and ^Th6 CDH _Screw (d) in methylcyclohexane at 25 °C. Orange- and green-colored vertical lines correspond to the wavelengths of λ = 365 and 420 nm, which were utilized for direct and sensitized photoexcitation of the molecules, respectively. e, f, Circular dichroism (CD) spectra of ^Th4 COT _Saddle (e) and ^Th6 CDH _Screw (f) in methylcyclohexane at 25 and –20 °C, respectively. Blue- and red-colored traces represent the spectra of compounds obtained as the first and second fractions of the chiral HPLC, respectively