Synthesis, characterization, and preliminary intramolecular energy transfer studies of rigid, emissive, rhenium-linked porphyrin dimers

The reaction of pyridyl functionalized porphyrins with Re(CO)(5)Cl in THF results in the formation of porphyrin dimers which, despite incorporation of rhenium into the assemblies, remain fluorescent. The rigid compounds provide an efficient geometry and/or orbital pathway for singlet energy transfer, rendering these compounds suitable, in principle, for the study of both through-bond and through-space energy transfer. Derivatives containing both metallated and freebase porphyrins connected via the metal corners display efficient porphyrin-porphyrin energy transfer. The photophysical properties of the assemblies have been studied by both steady-state and time-resolved fluorescence techniques, yielding approximate rates and efficiencies for porphyrin-porphyrin energy transfer.