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Multi-Chromophore Systems for Light Induced Processes and Light Triggered Devices

Final Report Summary - ERG-LIGHT (Multi-Chromophore Systems for Light Induced Processes and Light Triggered Devices)

Supramolecular boxes, made of metallacycles of metallo-porphyrins axially connected by chromophores such as porphyrins, perylene-bisimide's (PDI) and corroles.

We have developed the facile and efficient preparation of supramolecular multi-porphyrin assemblies with a sandwichlike geometry. They are made by two metallacycles of zinc-porphyrins, [t,c,c-RuCl2(CO)2(Zn•4'c-DPyP)]2 connected through two linear linkers L, axially bound to the zinc ions inside the porphyrins, and can be formulated as {[t,c,c-RuCl2(CO)2(Zn•4'c-DPyP)]2}2{µ-L}2. Typically, also the L linkers are photoactive molecules. In particular, in collaboration with group of Prof. F. Würthner (Würzburg, Germany), we have prepared and structurally characterized supramolecular sandwiches in which L = perylene-bisimide dyes (PDI). The modular nature of these systems makes their construction particularly flexible and amenable of future developments. In fact, both the nature of the axial ligands L and that of the porphyrin metallacycle 1 can be varied. We have exploited this great potential for preparing a new series of assemblies, in which the cavity is more defined, and therefore potentially capable of including appropriate guest molecules. For this purpose we have used axial ligands L with three pyridyl appended groups. Two of such ligands are able to assemble three molecular metallacycles of zinc-porphyrins 1, leading to the formation of box-shaped assemblies, that can be formulated as {[t,c,c-RuCl2(CO)2(Zn•4'c-DPyP)]2}3{µ-L}2.

All the assemblies obtained have been completely characterized both in solution and in the solid state. The use of the synchrotron radiation at X-ray diffraction beamline of ELETTRA, Trieste (Italy) has been crucial to obtain the solid state structure of the above assemblies. Four other projects have been developed. They are partly completed and partly undergoing: introduction of linear linkers L possessing spin-cross over properties in order to obtain supramolecular assemblies for magnetic memories applications, in collaborations with the group of Dr. S. Bonnet, University of Leiden, The Netherlands and with Prof. A. Cornia, University of Modena, Italy; employment of another metallacycle consisting

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