Study On Fluorescent Probes For Metal Ions And Development Of Novel Molecules With Aggregation-induced Emission Enhancement Characteristics

This dissertation firstly described the synthesis of a series of rhodamine amide derivatives. The crystal structure of one compound in this series was obtained and served as the direct evidence for the existence of rhodamine spirolactam ring moiety in their molecular structures. Meanwhile, the application of these compounds as fluorescent probes for Cr2O72?, Cu2+ and Fe3+ by the rhodamine spirolactam ring"close-open"switch was also studied. The interaction between these fluorescent probes and metal ions could be divided into two kinds: metal ion-induced reaction and metal ion-induced chelation. In the former case, fluorescent probe underwent chemical reaction with metal ion to yield a product with different fluorescent character, thus produced signal change in the presence of metal ion; in the latter case, fluorescent probe chelated with metal ion to form a complex with different fluorescent property, which induced fluorescence change to the solution upon metal ion binding. Nevertheless, both of them were based on the metal ion-induced spirolactam ring"close-open"switch of rhodamine amide, with their advantages of significant absorption and fluorescence enhancement and optical signal above 500 nm that was resistant to sample background. Using rhodamine B hydrazide, Cr2O72? could be detected in acidic water with 0.3 ppb detection limit; Cu2+ could be quantified in neutral ethanol/water solution with a detection limit of 10 nM by rhodamine 6G salicyl hydrazone; Fe3+ with a concentration higher than 10?5 M level could also be monitored with a rhodamine amide as fluorescent probe in neutral water. All these three analytical protocols could be completed within half an hour, and with good resistance to other metal ions that commonly coexisted in water. Determinations of Cr2O72? and Cu2+ in drinking water and river water samples were also successfully achieved using these methods.In addition, a novel series of compounds with aggregation-induced emission enhancement (AIEE) characteristics were discovered and their spectral properties in different states were studied in this dissertation. The crystal structure of salicylaldehyde azine was obtained as a representative. The advantage of this new series of AIEE compounds was their ease of synthesis and low cost. By monitoring the significant fluorescence enhancement upon the formation of these AIEE compounds, hydrazine concentration in water could be detected using corresponding salicylaldehydes.