Redox‐ and Protonation‐Induced Fluorescence Switch in a New Triphenylamine with Six Stable Active or Non‐Active Forms

The synthesis, photophysical and electrochemical properties as well as theoretical calculation studies of a newly designed triphenylamine derivative are described. This original compound displays one neutral form, three oxidized forms, and two protonated forms with distinct photophysical characteristics. The interplay of the emission with the protonation or the redox state (electrofluorochromism) has been explored and an on–off–on–off fluorescence switching was observed in the case of oxidation and an on–on–off fluorescence switching in the case of protonation.     

How molecular electrochemistry may shine light by designing electrofluorochromic compounds

Luminescence and electrochemistry have been intimately associated for a long time in the framework of electrochemiluminescence, where the electrochemical signal triggers light emission through a redox reaction. More recently another aspect of this coupling has been developed in electrofluorochromism, where electrochemistry is used to monitor photoluminescence processes. This review aims to highlight some molecular structures allowing emission properties to be tuned electrochemically through either redox-active luminophores or dyads in which a redox moiety can (de)activate the luminescence of a nearby unit. The working principle and main applications are also briefly discussed.     

On the Mechanism of Au-Catalyzed Enynamide-yne Dehydro-Diels-Alder Reactions: An Experimental and Computational Study

Gold-catalyzed dehydro-Diels-Alder reactions of ynamide derivatives allow efficient access to a variety of N-containing aromatic heterocycles. A dual gold catalysis mechanism was postulated for transformations involving the formation of C−C bonds by reaction between a terminal alkyne and an enynamide fragment. In this article, complete experimental and computational investigations into the mechanism of such a transformation are reported. Support for a dual gold catalysis was found and it was shown that the concerted or stepwise nature of the cyclization event depends on the substitution of the ynamide moiety. The reaction was found to proceed in three stages: 1) formation of a σ,π-digold complex from the terminal alkyne, 2) cyclization to produce a gem-diaurated aryl complex, and 3) catalyst transfer to free the product and regenerate the σ,π-digold complex.