A GENERAL RULE FOR CIRCULAR-DICHROISM INDUCED BY A CHIRAL MACROCYCLE

A general rule for induced circular dichroism (ICD) of a chromophore located inside or outside the cavity of a chiral macrocycle is derived from the Kirkwood-Tinoco equation. When a chromophore moves from the inside of the cavity to the outside, the sign of ICD tends to be reversed. Outside the cavity, the absolute value of ICD is larger on the narrower-rim side of a macrocycle than on the wider-rim side. Furthermore, ideally a parallel-polarized electronic transition along the axis of the cavity should give 2 times larger ICD with opposite sign as compared with ICD caused by a perpendicular-polarized one.