Expanding the Chemical Space of Tetracyanobuta‐1,3‐diene (TCBD) through a Cyano‐Diels‐Alder Reaction: Synthesis, Structure, and Physicochemical Properties of an Anthryl‐fused‐TCBD Derivative

Abstract

Tetracyanobuta-1,3-diene (TCBD) is a powerful and versatile electron-acceptor moiety widely used for the preparation of electroactive conjugates. While many reports addressing its electron-accepting capability have appeared in the literature, significantly scarcer are those dealing with its chemical modification, a relevant topic which allows to broaden the chemical space of this interesting functional unit. Here, we report on the first example of a high-yielding cyano-Diels-Alder (CDA) reaction between TCBD (i.e., where a nitrile group acts as a dienophile) and an anthryl moiety (i.e., acting as a diene). The resulting anthryl-fused−TCBD derivative, which structure was unambiguously identified by X-ray diffraction, shows high thermal stability, remarkable electron-accepting capability, and interesting electronic ground- and excited-state features, as characterized by a thorough theoretical, electrochemical and photophysical investigation. Moreover, a detailed kinetic analysis of the intramolecular CDA reaction transforming the anthryl−TCBD-based reactant into the anthryl-fused−TCBD product was carried out at different temperatures.