| Due to its high sensitivity, nice selectivity, fast analysis with spatial resolutionand non sample-destructing or less cell-damaging, fluorescence probe might be thebest choice for metal ions detection. The last decade has seen a greatly increasinginterest in the development of small-molecule fluorescent probes for heavy andtransition metal ions. Among them, probes with fluorescence enhancement foranalytes have attracted particular attention. As such probes afford “turn-on” responsestoward metal ions which are more suitable for bioimaging applications and practicalsamples than those probes based on fluorescence quenching mechanism. However,many heavy and transition metal ions （e.g., Hg2+, Cu2+） are known as fluorescentquenchers. Therefore, it is still one of the difficult and hot spots to design andsynthesis highly sensitive and selective probes with fluorescence enhancementresponses toward transition metal ions. In this thesis, three novel fluorescence probesfor Hg2+or Cu2+detection with “turn-on” responses were investigated as follows:1. In chapter2, a highly sensitive fluorescence probe based on rhodamine Bderivative for Hg2+detection in DMF-water was developed. The fluorescenceenhancement of the probe is based on a Hg2+induced ring-opening mechanism. Therhodamine B thio-spirocyclic was synthesized by an accidental reaction. Due to a Satom introduced into the molecule as the unique recognition moiety, the probe couldafford a very nice selectivity for Hg2+detection over other common metal ions. It is acolorless, non-fluorescent compound, with the introduction of Hg2+, the probeinstantly exhibits a pink color, acompanied with an orange fluorescence inDMF-water （1:9, v/v） solution. With the experimental conditions optimized, the probeexhibits a dynamic response concentration range for Hg2+from1.0×10-8 to1.0×10-6 M, with a detection limit of2.5×10-9 M. In addition, the performance of the probecan not be interfered during a broad pH value from3.6to11.2.2. In chapter3, a new fluorescent probe of novel rhodanmine thiospirolactamderivative was developed for selective detection of Hg2+in pure aqueous samples. Inthe well designed probe, the thiospirolactam serves as both Hg2+binding unit andpre-electron-defect C centre, a phenoxide anion with very strong nucleophilicity ischosen as the attacking unit, and a benzene ring is introduced on the linker to affordsteric effect, which benefits for a more efficient nucleophilic reaction than previously reported probes, and thus an improved sensitivity towards Hg2+. It exhibits a stableresponse for Hg2+over a concentration range from1.0×10-8 to1.0×10-5M, with adetection limit of4.0×10-9 M. Most importantly, due to the high efficiency of thenucleophilic reaction, it works well in aqueous media with no additional organiccosolvent, which make it possible for the probe to detection of Hg2+in pure aqueoussamples such as natural water samples and biological samples. The response of theprobe to Hg2+is highly selective and pH-insensitive, with a fast response time. Allthese unique features make it particularly favorable for cellular Hg2+imagingapplications. It has been preliminarily used for highly sensitive monitoring of Hg2+level in living cells with satisfying result.3. In chapter4, copper ions can catalytic hydrolysis hydrazide structure to formcarboxylic. We have developed pyrene hydrazine based fluorescent probe fordetection of copper ions in its ethanol-water （1:1, v/v） solution. The pyrene hydrazidestructure can be catalyzed hydrolysis by copper ions, and then formation of pyrenecarboxylic acid structure, resulting in significantly enhanced fluorescence at375nm.With the experimental conditions optimized, the probe exhibits a dynamic responseconcentration range for Cu2+from4.0×10-8 to1.0×10-6 M, with a detection limit of1.4×10-8 M. In addition, the probe shows good selectivity for copper ions. |
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