LAUSR

Abstract The fluorescence detection of different electrolytes existing in body fluids represents a modern method for diagnosis of diseases. This work reports the use of a pyrazoline derivative as a new fluorescence chloride sensor based on a dynamic quenching mechanism. Moreover, we show that 1,3-diphenyl-5-{4-[(4-vinylbenzyl)oxy]phenyl}-4,5-dihydropyrazole is capable to detect multiple halides and behave differently depending on the nature of either the halide or the metal counterion. The optical properties of this pyrazoline in the presence of halides of alkaline and several transitional metals have been determined by UV–Vis and FL measurements in solution. Stern-Volmer equation used for fluorescence data analysis revealed interesting particularities depending on the selected quencher. We discovered that the aforementioned pyrazoline is highly sensitive to potassium chloride or iodide, but, is inert to potassium bromide. Quantum mechanical calculations were employed to generate the molecular models of the pyrazoline in ground and excited state, with the view to obtain the HOMO-LUMO energy gap and mapped electrostatic isopotential. Thus, it was possible to explain the sensitivity for chloride and establish the fluorescence quenching mechanism. This pyrazoline derivative may be used to expand the class of fluorescent materials with improved chloride sensitivity and develop multi analysis systems.