Metal-mediated multi-porphyrin discrete assemblies and their photoinduced properties

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.