Janus Luminogens with Bended Intramolecular Charge Transfer: Towards Molecular Transistor and Brain Imaging

The ingenious construction of electron donor-acceptor (D-A) system has been proven to be the major trend for novel advanced-performance optoelectronic materials. However, the related development is undiversified and become stereotyped in recent years, and the explorationsof new architecture with both prominentoptoelectronic property and innovatively coined optoelectronic mechanism are appealing yet significantly challenging tasks. We herein exploit a series of novel Janus luminogens, namely TAOs, with unique charge separation in asimple five-membered mesoionic ring.TAOs having low molecular weight present efficient aggregation-induced red/near-infrared emission with up to 21.5% of fluorescence quantum yield. A new mechanism termed as bended intramolecular charge transfer (BICT) is proposed to understand the fluorescence behavior. It is experimentally demonstrated that TAOs exhibit great potential for the use as molecular transistor, and can be efficiently utilized in brain imaging straightforwardly through intravenous postinjection.