Effects of Halogenation on Quinoline‐Malononitrile‐based AIEgens: Photophysical Properties Investigation and Wash‐Free Imaging

Abstract

AbstractDeveloping halogen‐functionalized fluorescent dyes with intriguing photophysical properties, including enhanced photostability, is particularly important for bioimaging. In this work, we synthesized two new halogen‐functionalized aggregation‐induced emission (AIE)‐active molecules, DQMF‐OH and DQMCl‐OH, based on the quinoline‐malononitrile chromophore. The halogen effect on the photophysical characteristics was detailedly studied by absorption and fluorescence spectroscopy, density functional theory calculations, and crystal structures. Compared with non‐halogen substituted AIE luminogen (AIEgen) DQM‐OH, the halogen substituted DQMF‐OH and DQMCl‐OH exhibited red‐shifted absorptions and emissions in the solution and solid state. In addition, DQMF‐OH and DQMCl‐OH also possessed enhanced fluorescence toward viscosity changes. These AIEgens served as remarkable imaging tools for cell tracking in a wash‐free manner. Furthermore, DQMF‐OH and DQMCl‐OH showed much more excellent photobleaching resistance than DQM‐OH. Our work sheds new light on developing fluorescent halogenated dyes with enhanced photophysical performances for biological applications.