Experimental and Theoretical Studies of the Pyrazoline Derivative 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-Pyrazole and its Application for Selective Detection of Cd 2+ ion as Fluorescent Sensor.

A simple fluorescent chemosensor 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4, 5-dihydro-1H-pyrazole (PY) has been synthesized for the detection of Cd 2+ ion.The fluorescent probe PY shows high selectivity for Cd 2+ in the presence of othermetal ions (Co 2+ , Cu 2+ , Hg 2+ , Mn 2+ , Zn 2+ , Fe 3+ , Pb 2+ , Ni 2+ , and Al 3+ ). The fluorescence intensity of the PY has been strongly quenched with increasing concentration of Cd 2+ (0-0.9 μM)via photoinduced electron transfer mechanism. The binding constant of Cd 2+ to PY for the 1:1 complex isfound to be 5.3 × 10 5  M -1 with a detection limit of 0.09 μM. The chemosensor was successfully applied for determination of Cd 2+ in different water samples (tap, river, and bottled water) showing good recovery values in the range of 94.8-101.7% with RSD less than 3%. Density functional theory (DFT) calculations were also performed to investigate electronic and spectral characteristics which are quite agreeable with the experimental value. The results show that the synthesized fluorescent chemosensor shows good selectivity towards Cd 2+ and can be readily applied for the detection of Cd 2+ in real samples including water samples.