One step synthesis of highly photoluminescent red light-emitting carbon dots from O -phenylenediamine and 2,4-diaminophenol as fluorescent probes for the detection of pH and Cr( vi )

• Published in: Analytical methods 2023-11, Vol.15 (42), p.5607-5619
• Main Authors: Wu, Yan, Zuo, Chengwei, Mou, Yujie, Wang, Hao, Hou, Yongrui, Su, Xiaodong, Jia, Zhenfu, Qiu, Huidong
• Format: Article
• Language: English
• Subjects: Aqueous environments; Carbon; Carbon dots; Chromium; Fluorescence; Fluorescent indicators; Hydrogen bonding; Hydrogen bonds; o-Phenylenediamine; pH effects; Phenylenediamine; Photoluminescence; Probes; Quantum dots; Quenching; Target recognition
• ISSN: 1759-9660; 1759-9679
• DOI: 10.1039/d3ay01323e

In this study, new red light-emitting carbon dots (R-CDs) that can selectively recognize Cr( vi ) were prepared using a strategy that utilizes 2,4-diaminophenol to enhance the fluorescence of O -phenylenediamine based carbon dots. The results showed that 2,4-diaminophenol increased the quantum yield (QY) of the carbon quantum dots (CDs), and that the QY of the CDs increased from their original value of 8.7% to 20.1% (R-CDs). The R-CDs show sensitivity to acidic conditions and maintain good linearity between pH = 1.00–4.00, making them useful as pH probes. Furthermore, the prepared R-CDs possess good solubility in water and are responsive to changes in Cr( vi ) concentrations in aqueous environments. The quenching of the R-CDs fluorescence was linearly correlated with the Cr( vi ) concentration within a range of 0–20 μM, with a lower detection limit of 66 nM. The detection mechanism is attributed to the formation of hydrogen bonds between Cr( vi ) and the R-CDs, resulting in the fluorescence quenching of the R-CDs. The R-CDs can be considered effective multifunctional fluorescent probes for both pH and Cr( vi ) in aqueous environments. This study will provide new R-CD design strategies for probes that selectively identify specific target substances.