Catechol as a Co-Polymerization Mediator for Programmable Surface Chemistry Structure Synthesis of Carbon Dots

Red-emissive carbon dots (R-CDs) hold promise for bioimaging and optoelectronics, yet their synthesis under mild, scalable conditions remains challenging. Conventional hydrothermal routes demand high temperature and pressure, while ambient-pressure alternatives rely on strong acids and yield limited quantum yields without programmable surface control. This work reports a catechol-assisted ambient-pressure strategy that achieves hundred-gram-scale preparation of R-CDs by simple heating at ∼90°C. Catechol acts as a co-polymerization mediator, participating in formation of carbon dots while its dual hydrogen-bonding network suppresses functional-group detachment, stabilizes radical intermediates, and lowers the steric barrier for cyclization. This mechanism enables programmable tuning of hydrophilicity/hydrophobicity and emission wavelength by varying the precursor substituents. The hydrophobic carbon dots exhibit a solid-state quantum yield of 45.26% (encapsulated in polyvinylpyrrolidone), the highest reported, and enable white light-emitting diodes (WLED) with a color rendering index (CRI) of 94. The hydrophilic carbon dots (quantum yield 37.86%) are directly applied to deep-tissue in vivo imaging without surface modification. This work provides a versatile molecular engineering platform for sustainable synthesis of functional aromatic carbon nanomaterials.