New benzotriazole-based D–A–D type solvatochromic dyes for water content detection in organic solvents

Two new D-A-D structured organic dyes (LM1 and LM2) based on methoxy substituted triphenylamine (MeO-TPA) as the electron donor, N-aryl benzotriazole as the electron acceptor have been designed and synthesized for water content detection in organic solvents. Both dyes exhibit large stoke shift with solvatochromic properties and display apparent fluorescence quenching upon the addition of different amount of water in organic solvents. Compared to LM1, LM2 with stronger electron-withdrawing acceptor fluorinated benzotriazole possesses red-shifted absorption and fluorescence emission, enhanced intramolecular charge transfer (ICT) properties and stronger hydrogen-bonding interaction, resulting in a lower limit of detection (LOD) for water. The LODs in THF and 1,4-dioxane of LM2 are 0.009 % and 0.024 %, respectively, which indicates its great potential application in detecting water content in organic solvents.