Department of Chemistry, National Sun Yat-sen University, No. 70, Lienhai Rd., Kaohsiung 80424, Taiwan, Republic of China.
School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, No. 100, Shiquan 1st Rd., Kaohsiung, 80708, Taiwan, Republic of China.
Anal Methods. 2021 Oct 28;13(41):4949-4954. doi: 10.1039/d1ay01202a.
The phosphorescence of solid-state carbon dots (CDs) has been demonstrated to be susceptible to water molecules. However, solution-based CDs have been rarely exploited for phosphorescence detection of trace amounts of water in organic solvents. Here, we present a straightforward method to embed the CDs into NaCl nanocrystals and show their application for phosphorescence detection of the water content in organic solvents. The phosphorescent CDs inside NaCl nanocrystals were fabricated by hydrothermal treatment of poly(diallyldimethylammonium) (PDDA) polymers and their counter chloride ions (Cl) in the presence of NaOH. Because of the interaction with quaternary ammonium surface groups of PDDA-based CDs (PDDA-CDs), the Cl ions serve as a nucleation site to trigger NaCl nanocrystal formation. Electron microscopy and spectroscopy techniques demonstrate the embedment of PDDA-CDs into NaCl nanocrystals (PDDA-CDs@NaCl). The PDDA-CDs@NaCl exhibited excitation-independent phosphorescence and excitation-dependent fluorescence in ethanol, methanol, dimethyl sulfoxide, and dimethylformamide. In four different organic solvents, the phosphorescence QYs and lasting times of PDDA-CDs@NaCl range from 23 to 35% and 1.2 to 1.5 s, respectively. Once trace amounts of water are present in an organic solvent, the water-induced dissolution of NaCl nanocrystals switches off the phosphorescence of PDDA-CDs@NaCl. It was found that PDDA-CDs@NaCl was capable of detecting as low as 0.25% v/v water in ethanol and 0.125% v/v water in methanol. The above-discussed results provide fundamental insights regarding the embedment of phosphorescent CDs into a solid matrix as a solution-based sensor.
固态碳点（CDs）的磷光已被证明易受水分子影响。然而，基于溶液的 CDs 很少被用于在有机溶剂中痕量水的磷光检测。在这里，我们提出了一种将 CDs 嵌入 NaCl 纳米晶体中的简单方法，并展示了它们在有机溶剂中痕量水含量的磷光检测中的应用。在存在 NaOH 的情况下，通过聚二烯丙基二甲基氯化铵（PDDA）聚合物及其抗衡氯离子（Cl）的水热处理制备了磷光 CDs 嵌入的 NaCl 纳米晶体（PDDA-CDs@NaCl）。由于 PDDA 基 CDs（PDDA-CDs）的季铵表面基团与 Cl 离子的相互作用，Cl 离子作为晶核形成的触发点。电子显微镜和光谱技术证明了 PDDA-CDs 嵌入 NaCl 纳米晶体中（PDDA-CDs@NaCl）。PDDA-CDs@NaCl 在乙醇、甲醇、二甲基亚砜和二甲基甲酰胺中表现出激发独立的磷光和激发依赖的荧光。在四种不同的有机溶剂中，PDDA-CDs@NaCl 的磷光量子产率和持续时间范围分别为 23%至 35%和 1.2 秒至 1.5 秒。一旦有机溶剂中存在痕量水分，水诱导的 NaCl 纳米晶体溶解会关闭 PDDA-CDs@NaCl 的磷光。结果发现，PDDA-CDs@NaCl 能够检测到乙醇中低至 0.25%v/v 的水和甲醇中低至 0.125%v/v 的水。上述结果提供了关于将磷光 CDs 嵌入固体基质作为基于溶液的传感器的基本见解。
