Identifying molecular fluorophore impurities in the synthesis of low-oxygen-content, carbon nanodots derived from pyrene

Nadeesha L. Kothalawala, Sang Won Kim, Namhee Kim, Collan J. Henderson, Minsu Seol, Fuqian Yang, Seung Yeon Kwak, Kyu Young Hwang, Won Joon Son, Hyeon Jin Shin, Hyeonho Choi, Byeong Su Kim, Doo Young Kim

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Carbon dots (C-dots) are a promising class of carbonaceous nanomaterials for bioimaging, catalysis, and optoelectronics. However, their applications are disrupted by recent reports that bright molecular fluorophores are co-produced in the synthesis of C-dots, in particular ones prepared through a bottom-up approach (carbon nanodots (CNDs)), commonly derived from citric acid precursors. The presence of highly emissive molecular fluorophore species obscures the true performance of CNDs and severely challenges the development of CNDs. Here we observe that the issue of molecular fluorophore impurity is still problematic for CNDs which are derived from a different type of precursor, polycylic aromatic hydrocarbons (PAHs). In this study, low-oxygen-content CNDs and small molecular fluorophores are co-produced through hydrothermal condensation of nitropyrene. Extensive and systematic characterization following column chromatographic separation and solvent-induced extraction reveals that molecular fluorophores and CNDs are clearly dissimilar in structure and optical properties. This work highlights that rigorous separation and purification steps need to be taken not only for hydrophilic CNDs but also for low-oxygen-content CNDs.

Original languageEnglish
Pages (from-to)8324-8333
Number of pages10
JournalNew Journal of Chemistry
Issue number17
StatePublished - Apr 1 2022

Bibliographical note

Funding Information:
This work was supported by a Samsung GRO award. NHK and BSK appreciate the support from the National Research Foundation of Korea (NRF-2017M3A7B4052802). NK, FY, and DYK are grateful for the support by the NSF through the grant CMMI-1854554.

Publisher Copyright:
© 2022 The Royal Society of Chemistry

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Materials Chemistry


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