Novel Bisthienylethene Containing Ferrocenyl-Substituted Naphthalimide: A Photo- and Redox Multi-Addressable Molecular Switch

A new photochromic bisthienylethene system (BTE?NAFc) is reported in which the ferrocene unit (Fc) is incorporated into a naphthalimide chromophore as the central ethene bridging unit. The incorporated Fc unit in the photochromic system of BTE?NAFc has several effects on optical properties, such as fluorescence-modulation through photoinduced electron transfer (PET), a decrease in the photochromic cyclization quantum yield, and a selective two-step oxidation process. The ability to drive ring-opening and ring-closing reactions with a secondary redox-modulation provides increased functionality to the photochromic system. Based on these meaningful photo- and redox-modulation properties, five unprecedented multi-addressable states (BTE?NAFc, BTE?NAFc+, c-BTE?NAFc, c-BTE?NAFc+, and BTE+?NAFc+) and gated photochromism are successfully obtained within the unimolecular BTE platform, thus providing deeper insight into photochromic systems as multifunctional outputs.