Small molecule based water-soluble fluorescence material for highly selective and ultra-sensitive detection of TNT: Design and spectrofluorimetric determination in real samples

A novel water-soluble double-anthracene bridged material consisting of two cyclotriphosphazene cores (5) as a small molecule was designed and systematically synthesized. The developed small molecule was used for ultrasensitive and highly selective spectrofluorimetric determination of TNT in 100 % aqueous media. The characterization of 5 was examined by standard spectroscopic techniques. Fluorescent sensor features of 5 towards TNT were examined by UV-vis absorption, steady-state-, time-resolved-, and 3D-fluorescence measurements. The interaction and fluorescence mechanisms were investigated by DFT. The designed fluorescent sensor demonstrated a "turn-off" response towards TNT and required measurement conditions were evaluated for the determination of TNT in environmental waters. The LOD and LOQ for TNT were found as 0.030 and 0.091 mg.L-1 in the linear response of 0.02-15.00 mg.L-1 (R2 = 0.9964), respectively. This study demonstrated that 5 selectively interacted with TNT via intermolecular pi-pi and CH-pi stacking interactions which led to effective electron transfer resulting in a "turn-off" response. The spectrofluorimetric determination of TNT in environmental waters was performed under optimized conditions and the accuracy was evaluated with HPLC and spike/recovery test. In addition, paper-based test kits were prepared for the detection of TNT, which can be easily used for highly selective, portable, sensitive, and rapid field analysis.