ABSTRACT
The photoisomerization of alkenes is one of the most well investigated fundamental photoreactions. In particular, the geometrical photoisomerization around the C¼C double bond has attracted much attention from theoretical, mechanistic, and synthetic points of view. In the late 1960s and early 1970s Nobel laureate G. Wald demonstrated that the photochemical Z-E isomerization of rhodopsin is an essential process in vision [1-5]. Rhodopsin contains an 11-(Z )-retinal chromophore 1Z tethered to an opsin protein through a Schiff base linkage. This chromophore readily isomerizes to the (E )-isomer with light stimulus at wavelengths around 500 nm, which is followed by sequential structural changes, eventually leading to its release form the protein. The photoisomerization takes place in about 200 fs and in a quantum yield of up to 0.67 (Sch. 1) [6-10].
