Development of supramolecular machines allowing for mechanical communication between molecules

Ferrocene, a double-decker organometallic compound that generates an angular motion, can be used as a unique rotary module for molecular machines. Actually, we have developed novel molecular machines that consist of photochromic and l, l', 3, 3'-tetrasubstituted ferrocene units. Since l, l', 3, 3'-tetrasubstituted ferrocene derivatives are chiral, their conformational changes are able to be monitored by circular dichroism spectroscopy. As photochromic units, we adopted azobenzene and diarylethene derivatives, which undergo elongation/contraction motions in response to UV/visible light. Thus, the motions of the photochromic units accompanied by the photoisomerization processes can be transferred to the ferrocene unit to generate an angular motion, by taking advantage of interlocking a ferrocene-based rotary module with a photochromic unit through both covalent and non-covalent bond. This design strategy, which mimics real artificial machines in our daily life, would allow for not only design of gigantic molecular machines and but also remote control of molecular events.