Physicochemical and Photophysical investigation of newly synthesized carbazole containing pyrazoline-benzothiazole as fluorescent chemosensor for the detection of Cu2+, Fe3+ & Fe2+ metal ion

Abstract Pyrazoline-benzothiazole derivative 3-(2,5-dimethylthiophen-3-yl)-5-(9-ethyl-9H-carbazol-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)benzo [d]thiazole (TCPT) was synthesized by the reaction of (2 E )-1-(2,5-dimethylthiophen-3-yl)-3-(9-ethyl-9 H -carbazol-3-yl)prop-2-en-1-one with 2-hydrazinyl benzothiazole. The structure of the TCPT was established by the IR, 1 H NMR, 13 C NMR spectroscopic techniques and elemental analysis. Photophysical and physicochemical properties of the TCPT dye was studied by absorption and fluorescence spectroscopy. Different photophysical parameters of the TCPT such as dipole moments stoke shift oscillator strength and fluorescence quantum yields were strongly affected on the polarity of the solvents. An effect of two surfactants CTAB and SDS with TCPT dye was studied and it can be used as probe to determine the critical micelle concentration (CMC) of the CTAB and SDS surfactants. Moreover, TCPT dye can be use as a fluorescence chemosensor for the detection of Cu 2+ , Fe 3+ and Fe 2+ metal ions. According to the obtained data, the fluorescence intensity of the TCPT has been decreased intensity of the fluorescence spectra significantly by the concentration dependent manner. So the TCPT can be used as on to off fluorescence chemosensor for the detection of Fe 3+ metal ion. Quenching behavior was explained by the Benesi-Hilderbrand, Stern-Volmer and Job's-plot mechanism.