A porphyrin array in the antenna pigments of natural light-harvesting complexes, including chlorophyll, which absorbs photons from light and then enables an energy transfer relay of photon-excited excitons to a reaction centre, is of great importance for light harvesting in nature. Herein, a 2-dimensional porphyrin covalent array with J-J, J-H and H-H aggregated stacking configurations of transition dipoles was synthesised and verified experimentally using X-ray diffraction and photophysical measurements combined with first-principles calculations of the structures. The ordered array of light-sensitizing porphyrins with J-J and J-H configurations serves as a funnel to transport excitons via both Forster and Dexter energy transfer mechanisms, thereby enabling the rapid and long-range transfer of excitons to the exciton-accepting reaction centre upon panchromatic photon absorptions. This enhanced transfer boosts the collection of photons to the reaction centre by approximately 20-fold, far exceeding the absorbed light energy in the single porphyrin unit. Additionally, the covalent bonds between porphyrins, resulting in the formation of channels for excitons, exhibited chemical stability even in a strongly acidic solution, in addition to thermal stability up to a high temperature in air.

Energy transfer relay upon panchromatic light absorption by two-dimensional porphyrin covalent arrays

251st National Meeting (2016)

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