Bandrowski’s Base Revisited: Toward a Unprecedented Class of Quinonediimines or New Two-Way Chromophoric Molecular Switches

Temperature-controlled reactivity places Bandrowski's base 3 at the crossroads of a new versatile strategy for the preparation of two different categories of chromophores. We describe the access to a new class of quinonediimines (8) with an extended pi-conjugation owing to the presence of imine functions. Under slightly different conditions, Bandrowski's base appears to be the precursor of choice in the preparation of a novel pH- and light-dependent binary molecular switch. This molecule (11) is constituted of a benzobis(imidazole) core that can be reversibly protonated and a diarylethene unit which can be reversibly converted into its closed form upon irradiation. Triggered by two independent variables, 11 provides four distinct optical states for molecular number processing.