Toward long-distance mechanical communication: Studies on a ternary complex interconnected by a bridging rotary module

A heterotropic ternary complex was obtained from a photochromic dithienylethene derivative bearing pyridyl groups (1), a chiral tetrasubstituted ferrocene as a scissoring component bearing two pyridyl and free-base porphyrin groups (3*), and a biaryl derivative as an intermediately bridging component bearing four zinc porphyrin handles (2). The three components are connected together via bidentate coordination bonds and mechanically interconnected. Exposure of the ternary complex to UV or visible light allowed for the isomerization of 1. This configurational change gave rise to an angular motion of 2, resulting in a scissoring motion of 3*. In the absence of 2, the isomerization of 1 does not lead to any defined motions of 3*. Thus, the heterotropic ternary complex may be regarded as a prototype of "molecular reacher" for remote manipulation of molecular events.