Porphyrins and Other Chromophores with Antioxidant Substituents

Oxoporphyrinogens^1,2 are a class of porphyrinoid generally containing a tetrapyrrole macrocycle with oxo or oxocyclohexadienylidene groups substituted at their periphery. They are unique in that their physical structures are coupled to their electronic structures depending on the electrochemical state of the molecule. Variations in electronic conjugation over the core tetrapyrrole and substituents affect electronic absorptive properties. Using these features we have developed oxoporphyrinogens as molecular switching elements and for sensing applications involving chemical species including water and chiral compounds.^3,4 Tetrapyrroles with two or four conjugating substituents as well as corroles have been prepared and investigated for their properties depending on tautomerism,⁵ guest binding by hydrogen bonding and structural changes due to photoredox processes. The syntheses and mechanisms of action of the switching and sensing properties will be presented and discussed. Oxoporphyrinogens were developed from a porphyrin substituted with antioxidant 2,6-di-t-butylphenol groups. We have also investigated the synthesis and properties of other similarly substituted chromophores and will discuss some of the relevant properties.^6,7

References

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