Switchable Interporphyrin Interaction in an Anthraquinone-Bridged Porphyrin Dimer

• Published in: Journal of the Chinese Chemical Society (Taipei) 2013-07, Vol.60 (7), p.986-990
• Main Authors: Mai, Chi-Lun, Huang, Yi-Lin, Chiu, Chien-Lan, Lin, Hsin-Yu, Lin, You-Shiang, Yeh, Chen-Yu
• Format: Article
• Language: English
• Subjects: Anthraquinone; Electronic coupling; Molecular switch; Porphyrins
• ISSN: 0009-4536; 2192-6549
• DOI: 10.1002/jccs.201300149

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 E1/2(ox1) = +0.94 and E1/2(ox2) = +1.01 V, corresponding to the first electron ion 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. The anthracene bridge mediates the electronic communication between the two porphyrin units in the dimer while the anthraquinone bridge interrupts the communicaiton. This system can be exploited in the application of molecular switches.