Switchable Interporphyrin Interaction in an Anthraquinone-Bridged Porphyrin Dimer

摘要

The synthesis of porphyrin dimer and monomer with an anthraquinone or diacetoxyanthracene unit has been achieved. The electronic absorption spectra show that the anthracene-bridged porphyrin dimer 2 has strong electronic coupling between the two porphyrin units as evidenced by significant band broadening whereas the anthraquinone-bridged dimer 1 does not show electronic communication. Porphyrin dimer 2 shows two overlapping 1-e~- oxidation processes at E_(1/2)(ox1) = +0.94 and E_(1/2)(ox2) = +1.01 V, corresponding to the first electron abstraction from the two porphyrin units and porphyrin 1 shows a two 2-e~-waves at +1.01, indicating no electronic coupling between the two porphyrin units. The anthraquinone-bridged system can be reversibly switched from cross conjugated (switch off) to linear conjugated (switch on) via two-electron reduction/oxidation reactions. This feature holds promise for the anthraquinone-based wires to be used as redox-controlled switches in molecular electronic devices.