Design And Synthesis Of Novel Fluorescent Probe Based On Small Organic Molecules

As a novel detection method, the fluorescent probe has been widely used in clinical diagnosis, biotechnology, molecular biology, biochemistry, materials science and environmental chemistry due to its fast development in recent years. It can transform the reaction in molecules into a fluorescent signal. Rhodamine, coumarin, BODIPY and cyanine are the most common fluorescent molecules. These small molecular fluorophores have been widely used of designig probes because of their high quantum yield, good light stability and cell penetrating ability, and low cell toxicity. So building up more kinds of fluorescent probes by small organic molecules is of great significance. In this paper, we synthesized novel fluorescent probes based on Rhodamine, phenanthrene-imidazole and BODIPY to detect Fe3+, Hg2+, Cr3+ and Cys.In the first part, we designed two kinds of reversible fluorescent probes. The synthesis process of the first molecule was combining Rhodamine B and binaphthol with ethylene diamine. After coordination with Fe3+, its fluorescent intensity was increased rapidly. The detection limit was as low as 1.83 × 10-7 mol/L. The second molecule was a combination of Rhodamine B and bipyridine with hydrazine. It could coordinate with Hg2+ leading to Rhodamine B ring opening. Besides, the complex could still react with I- or S2- releasing the probe. Therefore, we realized a multifunctional application of a probe molecule for detection of three kinds of ions. These two kinds of fluorescent probes was successfully applied in cell imaging experiments.In the second part, we used 1-hydroxypyrene-2-carbaldehyde and 3'-formyl-4'-hydroxy-4-carbonitrile as starting materials. It reacted with picolyl chloride, forming a stable distribution site, and continued reacting with phenanthrenequinone. The probe based on 1-hydroxypyrene-2-carbaldehyde was a ‘turn off' type fluorescent probe, and the other one based on 3'-formyl-4'-hydroxy-4-carbonitrile was a ‘turn on' type fluorescent probe. By the calculation, the detection limit of these two kinds of probes is as low as 10-8 mol/L.In the third part, we synthesized the fluorescent probe using BODIPY as fluorophore, and acrylate group as the testing group to detect Cys. This molecule itself had very strong fluorescence, and its fluorescence was quenched after adding Cys. It was successfully applied in A375 cell imaging experiments. At the same time, we used halogenated acetic acid ester as detection group, and compared the differences between chloride, bromide and iodide. We draw a conclusion that chloride is the best monitoring group and realize fast detection of Cys within 600 s.