A novel pyrazoline-based fluorometric "turn-off" sensing for Hg2+

A new and non-toxic pyrazoline derivative (4-[3-(4-hydroxyphenyl) 5 (2 thienly)-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide, compound 1) was used for metal ion selectivity based on fluorometric detection. The effects of different metal ions such as Li+, Na+, Ag+, Mg2+, Ca2+, Ba2+, Cd2+, Zn2+, Cu2+, Hg2+, Cr2+, Pb2+, Fe2+, Mn2+, Co2+, Fe3+, and Al3+ were investigated in terms of the photo-physical properties of compound 1 (1 mu M). According to the data obtained, the fluorescence intensity of compound 1 has been decreased significantly by Hg2+ ion in a concentration dependent manner and without interfering the presence of any other metal ion at the medium in contrast to the other seventeen metal ions. The binding constant (8.06 x 10(4)M(-1)) of Hg2+ to compound 1, LOD value (14.54 mu M) of Hg2+, possible interaction mechanism between Hg2+ and compound 1 and the possibility of practical uses of compound 1 as selective fluorometric "turn-off" were reported this study. It was determined that the relative standard deviations (RSD) of four measurements were less than 20%. Novel sensor, compound 1 at 1 mu M, showed a linear range in the 20-200 mu M Hg2+ concentration with R = 0.99 value (correlation coefficient). Its response time was less than 1 min. As conclusion, compound 1 seemed as good and selective candidate for fluorometric "turn-off" sensor for Hg2+ detection. (C) 2017 Elsevier B.V. All rights reserved.