Ruthenium-mediated assemblies

Abstract The metal-driven construction of multi-porphyrin assemblies, which exploits the formation of coordination bonds between exocyclic donor site(s) on the porphyrins and metal centers, has recently allowed the design and preparation of sophisticated supra-molecular architectures whose complexity and function begin to approach the properties of naturally occurring systems. Within this framework, meso-pyridyl/phenyl porphyrins (PyPs), or strictly related chromophores, can provide geometrically well-defined connections to as many as four metal centers by coordination of the pyridyl peripheral groups. Several discrete assemblies of various nuclearities, in which the pyridylporphyrins are connected through external coordination compounds, have been constructed in recent years. In this review, we summarize recent work in this field from our and other laboratories. The photophysical properties of some ruthenium-mediated assemblies of porphyrins prepared by our group are also described. 

As anticipated already, metalation of the ruthenium-mediated multiporphyrin adducts described above introduces new sites for further axial coordination and basically makes them suitable for being used as building blocks in the hierarchical assembly of higher order adducts. 

Acknowledgements Most of the X-ray structures of ruthenium-mediated assemblies of porphyrins mentioned or showed in this contribution were solved by Prof. Ennio Zan-grando (Dipartimento di Scienze Chimiche, Universita di Trieste), who also very kindly provided the new drawings. Part of the work summarized here was financially supported by the donors of the Petroleum Research Fund, administered by the ACS, (grant ACS PRF 38892-AC3) and by MIUR (PRIN 2003 no. 2003035553 and F1RB-RBNE019H9K projects). 

This review chapter seeks to highfight the advances in the utilization of ruthenium-mediated ROMP to produce BCs for the assembly of bulk periodic nanostructures, while encouraging future research into the use of this polymerization methodology for the production of new materials, which is limited only by one s imagination. 

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