Switchable Interporphyrin Interaction in an Anthraquinone‐Bridged Porphyrin Dimer

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 1-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.