Oxygen‐Doped PAH Electrochromes: Difurano, Dipyrano, and Furano‐Pyrano Containing Naphthalene‐Cored Molecules

Abstract In this work, we report the synthesis of O‐doped naphthalene‐based electrochromes. Exploiting the CuO‐mediated Pummerer oxidative cycloetherification reaction, a series of 1,4‐ and 1,5‐disubstituted naphthalene‐cored dipyrano, difurano, and furano‐pyrano polycyclic aromatic hydrocarbons (PAHs) have been prepared. Steady‐state UV‐Vis absorption and emission investigations showed that the spectroscopic profile strongly depends on the O‐doping topology, with the dipyrano and the difurano derivatives demonstrating the most red‐shifted and blue‐shifted electronic transition, respectively. Computational investigations revealed that the cycloetherification reaction raises the HOMO energy level (while the LUMO remains largely unaffected), with the dipyrano derivatives displaying the highest values. Spectroelectrochemical measurements showed that, depending on the O‐topology and the type of O‐ring, different electrochromic responses could be obtained with colour transitions featuring high contrasts involving yellow, pink, orange or blue colours.