Modulating carbon dots from aggregation-caused quenching to aggregation-induced emission and applying them in sensing, imaging and anti-counterfeiting.

Aggregation Induced Emission Carbon Dots (AIE-CDs) address the problem of conventional CDs being quenched in the solid-state. However, there are still challenges in comprehending the luminescence mechanism. This work proposed a strategy for preparing green, yellow, and near-infrared CDs by modifying the functional groups on the precursor from hydroxyl and amino to p-methylenediamine, in which electronic supply capacity determined the redshift. Additionally, The CDs' properties transformed from Aggregation-Caused Quenching (ACQ) to AIE was realized by substituting non-rotatable hydroxyl or amino groups with the rotatable p-methylenediamine on the precursor. The resulting CDs were then applied in multifield. C-CDs was used for ratiometric detection of Al and F in pure water through three methods including fluorometer, test strip and smartphone. R-CDs was used for imaging cell nucleus and zebrafish. NIR-CDs (λ = 676 nm) exhibits dual emission, AIE and phosphorescent characteristics was used for triple anti-counterfeiting and binary information encryption. In summary, our finding presented a strategy for preparing multicolor CDs, proposed a mechanism for the transition of CDs from ACQ to AIE, and explore their multiple applications in anti-counterfeiting, information encapsulation, sensing and imaging.