Synthesis of dithiaporphyrin based singlet-singlet energy transfer systems

Abstract

The synthesis of the first alkynyl core-modified porphyrin building block, 5,10,15,20-tetrakis(4-ethynylphenyl)-21,23-dithiaporphyrin (N₂S₂ core), is reported. The building block was used to construct donor-appended dithiaporphyrin systems under mild palladium-coupling conditions. The porphyrin building block appended to four boron–dipyrrin units, (BDPY)₄S₂TPP, did not show any energy transfer from the BDPY unit to the central dithiaporphyrin core. However, the pentaporphyrin containing a central dithiaporphyrin sub-unit and four peripheral normal porphyrin sub-units (N₄ core) showed efficient energy transfer from the peripheral N₄ porphyrins to the central N₂S₂ porphyrin.