Synthesis and Unique Photoluminescence Properties of Nitrogen‐Rich Quantum Dots and Their Applications

Abstract

Nitrogen-rich quantum dots (N-dots) were serendipitously synthesized in methanol or aqueous solution at a reaction temperature as low as 50 °C. These N-dots have a small size (less than 10 nm) and contain a high percentage of the element nitrogen, and are thus a new member of quantum-dot family. These N-dots show unique and distinct photoluminescence properties with an increasing percentage of nitrogen compared to the neighboring carbon dots. The photoluminescence behavior was adjusted from blue to green simply through variation of the reaction temperature. Furthermore, the detailed mechanism of N-dot formation was also proposed with the trapped intermediate. These N-dots have also shown promising applications as fluorescent ink and biocompatible staining in C. elegans.

Surface enhanced Raman scattering on SiO2/Ag nanoparticles aggregate and preparation of nitrogen-doped carbon dots by pyrolysis of Co(2,2′-bipyridine)2(dicyanamide)2

“…[48] The strong peaks at 2924 and 2852 cm ¡1 , respectively, are due to the stretching vibrations of ÀCH 2 groups. [49] The peak at 1653 cm ¡1 can be associated with the amideÀcarbonyl (ÀNHÀCOÀ) stretching vibration. [50] The observed vibration mode of amideÀcarbonyl group suggests that we have obtained the nitrogen-doped CDs.…”

A Photochemical Avenue to Photoluminescent N-Dots and their Upconversion Cell Imaging

“…In our previous work, we prepared N-dots by a thermodynamic method and obtained a muddy solution with the presence of large particles28. However, through this photochemical avenue, we obtained a clear brown solution of N-dots.…”

“…In our previous study, we proposed a mechanism for the thermal preparation of N-dots by trapping a nitrene intermediate with methyl acrylate 28 . In this study also, we tried to use methyl acrylate to trap the photochemically generated active nitrene intermediate.…”

“…The only difference was that the intensity of the peak at 1544 cm −1 (N–H bending vibration) was higher in the thermodynamic method than that in the photochemical method. This is because in the thermodynamic method, the aziridine moieties were attacked by methanol, resulting in the opening of the aziridine rings to form more –NH bonds 28 . In the photochemical method, the N-dots were quickly formed with the dominant unattacked aziridine moieties.…”

Nitrogen-doped carbon dots derived from polyamindoamine dendrimer

“…Among these, nitrogen doping or using nitrogen containing precursors has been proved to be a very effective route for tailoring the properties of CDs, since N atom possesses comparable atomic size and five valence electrons for bonding with carbon atoms 30,31 . Chen et al 32 used 2azidoimidazole as the precursor, via a hydrothermal process at 70 o C overnight, and they prepared nitrogen-rich CDs with QY value as 33%. Yu et al 33 synthesized nitrogen-doped CDs from bee pollens and applied in bioimaging and catalysis.…”