Phenanthridium‐based conjugated probe for selective detection of anionic surfactant

The quaternary ammonium complex of (2‐(methylthio)indeno[1,2,3‐gh]phenanthridin‐1‐yl)(phenyl)methanone (QAC) has been employed as a new and simple fluorescence sensor for detection of the anionic surfactant; sodium dodecyl sulphate (SDS), through fluorescence light‐up. The generation of electrostatic interaction and associated intermolecular arrangement between the probe and anionic surfactant is responsible for the fluorescence enhancement and subsequent selectivity towards the anionic surfactant. Concurrently, the probe was unaltered by the presence of cationic and non‐ionic systems. Utilizing this property, we were able to construct a facile and efficient method for the detection of anionic surfactants, featuring LOD values up to 1.1 μM concentrations in dimethylsulfoxide solvent. The light‐up detection was also confirmed via lifetime studies, with superior increments in average lifetime decay values (0.33–2.7 ns). The practical/real‐time applications of probe QAC as a sensor have also been investigated and successfully demonstrated via its ability to detect anionic surfactants from commercially available home usage products.