Fluorescent Molecular Switches Containing GFP-Like Chromophores and Dithienylethene

Meta-amino-substituted green fluorescence protein chromophore (GFPc) (m-DMABDIs) are highly emissive in aprotic solvents. However hydrogen bonding interactions between the chromophore and protic solvents could induce a fast nonradiative decay process that quenches the fluorescence. Among the various types of photochromic molecules, dithienylethene (DTE) derivatives are the most promising systems for applications as molecular switches, because they undergo ring-closing and ring-opening reactions when irradiated with UV and visible light repeatedly, with an excellent thermal stability and a high degree of fatigue resistance. This thesis aims to take the advantage of m-DMABDI chromophore and dithienylethene switch to form two fluorescent molecular switches, name DTE-m-D1A1 and DTE’-m-D8A1, that can be operated in both solution and in the aggregates. The on-off fluorescence switches rely on the solvent proticity, and the on-off switch in the aggregate form relies on the ring-closing and ring-opening reactions of the dithienylethene moiety. The results show that DTE-m-D1A1 and DTE’-m-D8A1 perform the expected properties, but the thiophene groups of dithienylethene lower the fluorescence of the chromophore, making the efficiency of AIE not ideal and thus the low on-off fluorescent ratio in the aggregates. A non-thiophene switch might improve the performance. We also systematically investigated the potential quenchers of m-DMABDI to facilitate the future design of related systems.