Synthesis and properties of diads based on tetra-aryl porphyrins and ruthenium bis-terpyridine-type complexes

Four diads consisting of a free-base or zinc aryl-porphyrin associated with two ruthenium(II) bis(terdentate) complexes (non-cyclometallated Ru ( N 6) or cylometallated Ru ( N 5 C )) have been synthesized. The strong electron-withdrawing properties of the Ru ( N 6) as compared to the Ru ( N 5 C ) complex have been illustrated by their electrochemical and spectroscopic properties. Emission spectra of the diads and the reference compounds have shown that very efficient fluorescence quenching occurs, probably by energy transfer processes from the porphyrin to the 3 MLCT excited state of the ruthenium unit.