Hydrophobic Carbon Dots from Aliphatic Compounds with One Terminal Functional Group

In the preparation of carbon dots (C dots) through pyrolysis, organic molecules with multiple functional groups are popular, and monosubstituted compounds, such as aliphatic amines, are used only as an auxiliary component. Here, we provide a strategy to transfer aliphatic amines and aliphatic aldehydes to C dots in the absence of any other reagent under mild conditions. In a typical experiment, C dots were facilely obtained by refluxing dodecylamine (C-12-NH2) in chlorobenzene, which shows blue emission with wavelength-dependent characteristics. The C dots are soluble in a variety of organic solvents and can be further processed by either gel permeation chromatography or silica gel column chromatography, which gives highly pure C dots with absolute fluorescence quantum yield over 10%. The C dots are photoluminescent in the solvent-free state and can be used as fluorescent ink. They are also compatible with polymers such as poly(methyl methacrylate) and polydimethylsiloxane. Influence of the type of functional group was checked. Blue-emitting C dots were obtained as well by refluxing dodecanal in chlorobenzene, but using a compound bearing a carboxylic or hydroxy group only showed little success.