Controllable fluorescent switch based on ferrocene derivatives with AIE-active tetraphenylethene moiety

Stimuli-responsive supramolecular materials have attracted much attention because of their controllable microstructure and luminescence behavior. In this study, the fluorescent molecule ((1E)-1-((4-(1,2,2-triphenylvinyl)benzylidene)hydrazineylide-ne)ethyl)ferrocene (FcMe-TPE) with aggregation-induced emission (AIE) property and redox activity was synthesized. The morphology as well as fluorescence behavior could be modulated by changing solvent, adding oxidant or applying voltage, and the translation mechanism was explored in detail by means of density functional theory (DFT). Based on the presence of competitive hydrogen bonding, FcMe-TPE assemblies showed different aggregate behaviors and properties under different water contents (fw). As fw increased from 20% to 60%, the morphology of assemblies could be transformed from 2D sheet to elliptical crystal structure, then the precipitation gradually disappeared for the further increase of fw. At the same time, the addition of oxidant as well as the application of voltage could also cause changes in the fluorescence intensity of the assemblies. When the voltage increased from 0 V to 3 V, the fluorescence intensity increased and reached the maximum value at 1 V. Based on this property, the electrofluorochromic (EFC) device with low trigger voltage was made. This work provides a feasible strategy for controllable self-assembly and the fabrication of multiple fluorescence switches, which has potential practical application in the field of advanced anti-counterfeiting, intelligent display and information encryption.