Construction of Multiporphyrin Arrays Using Ruthenium and Rhodium Coordination to Phosphines

The synthesis of linear multiporphyrin arrays with mono- and bisphosphine-substituted porphyrins as ligand donors
and ruthenium(II) or rhodium(III) porphyrins as ligand acceptors is described. With appropriate amounts of the
building blocks mixed, linear dimeric and trimeric arrays have been synthesized and analyzed by 1H NMR and 31P
NMR spectroscopy. The Ru/Rh acceptor porphyrins can be located either at the periphery or in the center of the
array. Likewise, the monophosphine porphyrins can be positioned at the periphery, thus allowing a high degree of
freedom in the overall composition of the arrays. This way, both donor and acceptor porphyrins can act as chain
extenders or terminators. One of the trimeric complexes with two nickel and one ruthenium porphyrin has also
been analyzed by X-ray crystallography. Attempts have also been made to synthesize higher order arrays by
mixing appropriate amounts of the porphyrins; however, from the NMR data it cannot be concluded if monodisperse
five, seven, or nine porphyrin arrays are present or if the solutions are composed of a statistical mixture of smaller
and larger arrays.