| Noble metal nanoclusters have received much attention due to the quantum size effect to show special optical, electrical, and chemical properties and become one of research hotspots in the field of nanometer materials. Nanoclusters have a wide application prospect in the fields of chemical detection, biological markers, and novel fluorescent probes. Photocatalytic reactions play an important role in degradation and transformation process of organic matters in the environment. Ultraviolet(UV) light not only can catalyze reduction reaction, but also can catalyze oxidation reaction. For example, the mixed solution in the presence of organics was irradiated by UV light, which can produce the free radicals to reduce the silver ions to generate silver nanoclusters(Ag NCs). Therefore, we developed a novel and simple method to synthesis Ag NCs with UV light irradiation, and it was used to detect the inorganic ions. On the other hand, chromotropic acid is decolorized easily under UV light, copper ions can inhibit these decolorization and degradation phenomena. Thus, we establish a chemical sensor to detect the trace copper ion based on the UV illumination chromotropic acid. The main research contents are as follows:(1) A novel water-solution fluorescent Ag NCs have been yielded under Ultra-Violet C(UVC) light irradiation Ag(NH3)2OH solution. In this paper, we use carboxymethyl dextran(CMD) as a reducing and stabilizing agent in aqueous solution. The as-prepared Ag nanoclusters were characterized by TEM, HRTEM, UV-vis absorption spectroscopy and fluorescence spectroscopy. They were used as a fluorescent probe for sensitive and selective detection of halide ions based on the characteristic reaction between halide ions and the silver atoms on the surface of nanoclusters, which result in significant fluorescence intensity quenching. In this study, the sensing system has been applied successfully to detect I- in coexistence with Brunder NH3·H2O solution and detecte the total amount of Br- and I- under BR buffer. We found that different concentrations of iodide ions resulted in different fluorescence quenching of Ag NCs, and signal responses had a good linear relationship in the range of 1.0?10?10 to 1.0?10?7 mol/L. By a series of optimal experiments, it is come true to simultaneous detect Br- and I- in complicated samples. Finally, the CMD-capped Ag NCs would be a promising candidate to apply to detection of halide ions in real sample.(2) We know that Mn2+ can react with NH3·H2O to generate Mn(OH)2, which is not stable and easy to be oxidized to Mn O2. Mn O2 is not only poorly soluble in water, but also is difficult to soluble in alkaline solution. In NH3·H2O medium, the fluorescence of the Ag NCs,which have been yielded under UVC light irradiation Ag(NH3)2OH solution and used CMD as a reducing and stabilizing agent in aqueous solution, will become weakening and even quenching when added different concentration of manganese ions. Thus, this paper proposes a new method which used Ag NCs as a sensor to detect Mn2+ by fluorescent spectrophotometry under NH3·H2O medium. Under the optimum conditions, the sensing system shows many advantages such as good selectivity, high sensitivity and the lowest detection concentration of 1.0?10?10 mol/L.(3) We found that chromotrope 2R(CR) could be degraded easily under UVC light irradiation. We know that azo dye is a very good chelating reagent and CR is a type of azo dye. CR reacted with Cu2+ to form a stable complex(Cu2+-CR), suppressing the CR degradation under UVC irradiation. Thus, this paper developed a new probe to detect Cu2+ based on CR degraded easily under UVC light irradiation. We found that different concentrations of Cu2+ resulted in different degradation degrees of CR and had a good linear relationship in the range of 5.0?10?9 ~1.0?10?6 mol/L. It was used to detecte the content of Cu2+ ions in a real sample(human hair) with acceptable results. |
PDF Full Text Request