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Construction of nanoscale molecular presses displaying electrochemically and photochemically induced contrary linear motion of two plates

Final Activity Report Summary - NANO-PRESSES (Construction of nanoscale molecular presses displaying electrochemically and photochemically induced contrary linear motion of two plates.)

The objective of this project was the construction of advanced molecular architectures that assemble themselves when the individual components are mixed together. These components consist of two flat 'plates' and two linear rigid 'rails'. The emphasis of the project has been on the extremely complex synthesis of the plates. These have the form of a 'figure of eight', but the central point is replaced by a porphyrin unit. A porphyrin is a flat, highly coloured compound that has a rigid cavity that can act as a host for metal ions. We have appended two macrocycles to the porphyrin, where each macrocycle contains a phenanthroline unit. The function of the phenanthroline unit is to coordinate to metal ions, which can in turn coordinate to other molecules, and allow us to build up complex architectures taking advantage of the coordination characteristics of the metal ions.

This project has had several major synthetic achievements in the field of porphyrin chemistry on the way to its final goal. Firstly, synthetic routes were established to create porphyrins appended with first one and then two macrocycles using previously unexplored starting materials. Furthermore, the routes required creating mono or bis macrocycles appended to a porphyrin were different, requiring a change of tactics between the two. The most important scientific achievement of the project was the use of coordination chemistry to self-assemble a multiply-threaded species. Each plate has two macrocycles containing a site that will bind to a metal. These sites are opposite one another ie at north and south of the porphyrin. Therefore, if we have a rigid rail that also contains two binding sites that are next to each other we should be able to thread the rails through the macrocycles in such a way that a molecule with a rectangular shape is formed. Of course, this is not the only possible product that could be formed and it is remarkable that this quadruply interlocked species is formed as the major product of the reaction.