Molecular Spectroscopic Studies On The Interactions Between Quantum Dots And Anthraquinone Compound And Copper Ions

In this study, thioglycolic acid capped core/shell CdTe/CdS QDs (TGA-CdTe/CdS QDs) and glutathione capped CdTe QDs (GSH-CdTe QDs) were synthesized in aqueous solution. The shapes of the QDs were chatacterized by transmission electron microscope (TEM). The interactions of QDs and anthraquinone compound and copper ions were studied by fluorescence spectrum, ultraviolet-visible absorption spectrum and so on.According to the experiment results, the interaction of quantum dots and rhein, emodin and chrysophanol were discussed in this paper. A rapid sensitive determination of rhein, emodin and chrysophanol methods were proposed. Besides, by using quantum dots and 9-anthroic acid to established the combination fluorescence probe to detect copper ions in water solution. The main studies are as follows:1. Molecular spectroscopic studies on the interactions of rhein and emodin with thioglycolic acid-capped core/shell CdTe/CdS quantum dots and their analytical applicationsWater-soluble TGA-CdTe/CdS QDs were synthesized. Then the interactions of rhein and emodin with TGA-CdTe/CdS QDs were evaluated by fluorescence and ultraviolet-visible absorption spectroscopy. Experimental results manifested that the high fluorescence intensity of TGA-CdTe/CdS QDs could be effectively quenched in the presence of rhein (or emodin) at 570 nm. Quenching intensity was both in proportional to the concentration of rhein and emodin in a certain range. Under the optimized conditions, the linear ranges of TGA-CdTe/CdS QDs fluorescence intensity versus the concentration of rhein and emodin were 0.09650～60 μg·mL-1 and 0.1175～70 μg·mL-1 with correlation coefficient of 0.9984 and 0.9965. The corresponding detection limits (3σ/K) of rhein and emodin were 0.0289 and 0.0352 μg·mL-1 , respectively. This proposed method had been applied in the determination of rhein and emodin in human urine samples successfully with remarkable advantages such as high sensitivity, short analysis time and easy operation. Based on this, a simple, rapid and high sensitive method to determine rhein (or emodin) was proposed.2. A simple fluorescence quenching method for determination of chrysophanol based on glutathione capped CdTe quantum dotsGlutathione capped CdTe quantum dots (GSH-CdTe QDs) were synthesized. And the interaction of chrysophanol with GSH-CdTe QDs was assessed by fluorescence and ultraviolet-visible (UV-vis) absorption spectroscopy. The high fluorescence intensity of GSH-CdTe QDs could be quenched in the presence of chrysophanol, which may result from the electron transfer process from chrysophanol to excited GSH-CdTe QDs. The fluorescence quenching intensity was in proportional to the concentration of chrysophanol in a certain range. Under the optimized conditions, the linear range of GSH-CdTe QDs fluorescence intensity versus the concentration of chrysophanol was 0.010-20 μg·mL-1 with correlation coefficient of 0.9918. The corresponding detection limits (3σ/K) of chrysophanol was 0.0030 μg·mL-1. This proposed method had been applied in the determination of chrysophanol in synthetic samples.3.9-Anthroic acid modulated glutathione capped CdTe quantum dots for ultrasensitive detection of copper ionA neoteric combination fluorescence probe for highly sensitive and selective detection of copper ion (Cu2+) in aqueous phase which is composed by 9-anthroic acid and glutathione capped CdTe quantum dots (GSH-CdTe QDs) has been developed. Corresponding experiment results manifest that the fluorescence spectrum of this combination probe has two main peaks while the excitation wavelength is 350 nm, which located at 569 nm and 413 nm respectively. In the present of Cu2+, the fluorescence intensities located at 569 nm and 413 nm have been quenched successively, and the quenching extents are directly promotional to the concentration of Cu2+ in a certain range, respectively. Under the optimized condition, the linear range of the fluorescence intensity (peak at 569 nm) versus the concentration of Cu2+ is 0.06595-40.00 μg·mL-1 with correlation of coefficient of 0.9973, meanwhile, the linear range of the fluorescence intensity (peak at 413 nm) versus the concentration of Cu2+ was 40.00～200.0μg·mL-1 with correlation of coefficient of 0.9922. The corresponding detection limits (3σ/K) of Cu2+ is 0.01978 μg·mL-1. This proposed method has been successfully applied to the determination of Cu2+ in synthetic samples with remarkable advantages including high sensitivity, selectivity and a considerable detection scope.