Two Sensitive Fluorescent BOPIM Probes with Tunable TICT Character for Low-Level Water Detection in Organic Solvents

Two novel Boron-fluorine derivatives bearing dimethylamino moieties, BOPIM-1 and BOPIM-2, were proposed as sensitive fluorescent sensors for low-level water quantification in organic solvents. Two BOPIMs exhibit typical phenomenon for an emission from a twisted intra-molecular charge transfer (TICT) state, the emission red shift and intensity weakening with solvent polarity. Introduction of trace amount of water to solvent resulted in fluorescent quenching, accompanied by the red shift of the emission, which was attributed to the formation of TICT excitation of BOPIMs by hydrolysis. A quantification method to detect water content was developed, described by a linear equation lg(I/I(0)) vs. lg φ(w) in the range of φ(w) (volume fraction of water) 0.001~0.01, 0.01~0.1, respectively. The experiment results of determination of water in real 1, 4-dioxane (Diox) samples proved that this method can be used in practical application.