Construction of carbon dots having aggregation-induced emission and intramolecular charge transfer properties

Aggregation-induced emission–fluorescent carbon dots (AIE-CDs) have applications in both academia and industry. In this study, triphenylamine-based CDs (T-CDs) prepared in acetic acid showing both intramolecular charge transfer (ICT) and aggregation-induced emission (AIE) were designed and synthesized. Intriguingly, the T-CDs fluoresced with different colors in solvents of different polarities: for example, in acetic acid, they showed blue fluorescence. In contrast, in the presence of water, aggregation and precipitation occurred because of the hydrophobic nature of the compound. With time, the increasing aggregation resulted in a loss in intramolecular rotational degrees of freedom, resulting in bright red emissions as a result of ICT and AIE. Interestingly, the T-CDs could be used for intracellular imaging and the lysosome-specific targeting of live cells.