Polyol-Mediated Synthesis of Nitrogen-Containing Carbon-Dots from Tetracyanobenzene with Intense Red Fluorescence

• Published in: Nanomaterials (Basel, Switzerland) Vol. 9; no. 10; p. 1470
• Main Authors: Lehmacher, Roman, Feldmann, Claus
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 16.10.2019; MDPI
• Subjects: 1,2,4,5-tetracyanobenzene; Carbon; carbon dot; Carbon dots; Decomposition; Emission spectra; Excitation; Fluorescence; Liquid phases; Nitrogen; nitrogen containing; Polyethylene glycol; polyol synthesis; red emission; Sensors; Spectrum analysis; Synthesis; Transmission electron microscopy; Wavelength; Germany
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano9101470

Nitrogen-containing C-dots were prepared by heating (160 °C, 1 h) 1,2,4,5-tetracyanobenzene (TCB) in polyethylene glycol 400 (PEG400). The as-prepared monocrystalline C-dots were 2–4 nm in diameter and contained 24.4 wt. % of nitrogen. They showed intense fluorescence under excitation at 400–500 nm as well as under excitation at 600–700 nm. In addition to an excitation-wavelength-depending emission at 400 to 650 nm, the emission spectra exhibited a strong emission peaking at 715 nm, whose position was independent from the wavelength of excitation. For this deep-red emission a remarkable quantum yield of 69% was detected. The synthesis of nitrogen-containing C-dotswas completely performed in the liquid phase. Moreover, the C-dots could be directly dispersed in water. The resulting aqueous suspensions of PEG400-stabilized nitrogen-containing C-dots also showed intense red emission that was visible to the naked eye.