Polymerization-driven photoluminescence in alkanolamine-based C-dots

Carbonized polymer dots (CPDs), a peculiar type of Carbon dots, show extremely high quantum yields, making them very attractive nanostructures for application in optics and biophotonics. The origin of CPD strong photoluminescence resides in a complicated interplay of several radiative mechanisms. To understand the correlation between CPD processing and properties, we have studied the early stage formation of carbonized polymer dots. In the synthesis, citric acid monohydrate and 2-Amino-2-(hydroxymethyl)propane-1,3-diol have been thermally degraded at 180°C. The use of an oil bath instead of a more traditional hydrothermal reactor has allowed to monitor the CPD properties at different reactions times. Transmission electron microscopy, time-resolved photoluminescence, nuclear magnetic resonance, infrared and Raman spectroscopy have revealed the formation of polymeric species with amide and ester bonds. Quantum chemistry calculations has been employed to investigate the origin of CPD electronic transitions. At short reaction times, amorphous C-dots with 80% quantum yield, have been obtained.