Condition-Triggered Single-to-Double Peak Transition of CPDs for Visual Detection of Water Content in DMSO

Abstract

Herein, we had synthesized blue fluorescent carbonized polymer dots (CPDs) via a facile hydrothermal method using p-aminophenol and ethylenediaminetetraacetic acid. The reduced density gradient (RDG) analysis reveals that the supramolecular interactions between hydrogen-bonded polyamide chains results in the strong blue emission. Whereas the orange emission arises from the hydrogen-bond-induced excited-state intramolecular proton transfer (ESIPT) between the CPDs and water. Density functional theory (DFT) calculation has confirmed that phenolic hydroxyl groups play a key role in fluorescence redshift as the synthesis temperature increases. It is worth noting that the constructed dual emission ratio probe exhibits a good curve relationship at a moisture content of 10%-40% through the fluorescence intensity ratio (I458/I564), with a detection limit of 0.0538% and a correlation coefficient R2 of 0.9971. The fluorescence color of the probe solution changes from blue to orange yellow, indicating its potential for on-site visual detection. It had been successfully applied to detect trace water in various organic solvents, edible oils, and traditional Chinese medicines.