An Interesting Small Molecule Fluorescent Probe for A Narrow Range (12.5∼13) pH and DMSO Detection

Aims: The development of a sensitive and visual analytical method for detecting and monitoring the change of pH has always attracted great interest because it plays a significant role in chemical reactions, environmental monitoring, and biological systems. Methods: In this paper, a simple condensation reaction from readily available substrates 2-hydroxy-1- naphthylaldehyde and malononitrile has been carried out to produce probe L with good aggregationinduced luminescence, and its chemical structure was confirmed by ¹H NMR, ¹³C NMR and ESI-MS. Objective: There is a conjugated system containing two electron-withdrawing cyano groups and an electron- donating hydroxyl group in probe L's molecular structure, exhibiting obvious fluorescence intensity and visible color change through intramolecular charge transfer (ICT) under different pH conditions. Results: Probe L assumes excellent fluorescence intensity in a DMF/H2O (1:9, v:v) mixed solvent system, and exhibits good reversibility in a very narrow range of pH values (pH = 12.5∼13). In addition, probe L can also selectively identify solvent DMSO by the induction of fluorescence quenching. Conclusion: Probe L can be used for the analysis and visual detection to pH change in DMF/H2O system, and it may also be used as the indicator for the detection and monitoring of trace amounts of DMSO.