Highly conjugated donor–acceptor dyad based on tetrathiafulvalene covalently attached to porphyrin unit

A novel and highly conjugated donor–acceptor dyad consisting of tetrathiafulvalene unit covalently attached to a porphyrin unit has been synthesized and characterized. As compared to tetraphenylporphyrin, the fluorescence intensity and lifetime of the dyad was decreased owing to photoinduced electron transfer between the tetrathiafulvalene and porphyrin units in the excited state. The fluorescence intensity of the dyad was recovered dramatically upon the addition of Fe(ClO4)3·6H2O to a solution of the dyad, and the fluorescence intensity grows with an increasing amount of Fe(ClO4)3·6H2O. More importantly, the fluorescence intensity of the dyad can be reversibly modulated by the sequential electrochemical oxidation and reduction of the tetrathiafulvalene unit, thus a new redox fluorescence switch based on this dyad has been constructed.

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► A novel donor–acceptor dyad has been synthesized and characterized.
► The fluorescence quenching behavior of the dyad has been investigated.
► The fluorescence intensity of the dyad can be reversibly modulated.
► A new redox fluorescence switch based on dyad 1 has been constructed.