Control of π-electron rotation in chiral aromatic molecules by nonhelical laser pulses

Turning on the ring current: π Electrons in a chiral aromatic molecule, such as dichloro(3,6)pyrazinophanes (see scheme), can be rotated along the aromatic ring by linearly polarized laser pulses. Selective generation of an (approximate) angular momentum eigenstate consisting of optically allowed, quasi-degenerate π-electronic excited states is responsible for the rotation. The direction of the photoinduced ring current is controllable in each enantiomer. (Figure Presented).