Design, Synthesis And Application Of Organic Fluorescent Probes

As the smallest anion with high charge density, fluoride ion plays an important role in various health and environmental issues. It was proven to be critical for the protection of dental and the treatment of osteoporosis. However, the excess intake of fluoride can lead to the disorder of nerve and endocrine system, skeletal disease, mottled teeth and nephrolithiasis. Because human body absorbs fluoride ion routinely from water, toothpaste and other fluoride supplements, developing a new method for the quantitative determination of fluoride ion on real life water and toothpaste is of great importance.Hypochlorous acid (HC1O)/hypochlorite (CIO’) widely exists in our daily life and plays a significant role in many physiological processes. In our daily life, HOC1 is used as disinfectant, deodorant and bleaching agent. Biologically, endogenous HOC1 contributes towards the human immune defence system, and kills a wide range of bacteria and pathogens in cells. Meanwhile, abnormal levels of HOC1 may cause inflammatory, atherosclerosis, rheumatoid arthritis, respiratory distress, cardiovascular diseases and even cancer. Therefore, selective and sensitive detection of HOC1 under physiological condition is needed.Fluorescence-based methods have gained great attention because of their high selectivity, high sensitivity, low cost, real-time essay and in vivo imaging studies. Considering the optical characteristics and the structure of the common fluorophores, we designed and synthesized two fluorescent probes for the detection of fluoride ion and HOC1 based on pyrazoline, BODIPY and rhodamine fluorophores. We further explored their optical properties and application on real life samples and in living cells. The content includes the following two parts.1. Design, synthesis, optical characteristics and application of pyrazoline-based fluorescent probe for fluoride ion.Tert-butyldimethylsilyl (TBDMS) is a good protecting group of-OH to form O-Si bond, because F" can easily trigger the cleavage of Si-O bond. Based on the above reaction, we designed and synthesized a novel pyrazoline-based fluorescent probe for the detection of fluoride ion with high selectivity and sensitivity in aqueous media. After the reaction with NaF, desilylation reaction of the probe can be induced to the fluorescence quenching, accompanied with the fluorescence quantum yield changing from 0.734 to 0.088. The fluorescence intensity showed a good linear relationship with the concentration of F- in the range of 1～10 μM with the detection limit of F" 0.74 μM. The probe could be a promising fluorescent probe for quantitative determination of F- in environmental water samples and toothpaste, which would be an excellent candidate for highly selective and sensitive detection of F".2. Design, synthesis, optical characteristics and application of boron dipyrromethene/rhodamine-based ratiometric fluorescent probe for hypochlorous acid.Considering the absorption band of rhodamine fluorophore and emission band of BODIPY fluorophore, we developed a ratiometric fluorescent probe based on boron dipyrromethene (BODIPY) and rhodamine-thiohydrazide fluorescence resonance energy transfer (FRET) platform for the detection of hypochlorous acid (HOC1) accompanied that rhodamine-thiohydrazide performed as the detection group, BODIPY performed as the donor, rhodamine acted as the acceptor. After the reaction with hypochlorous acid, the fluorescence color of the probe changed from green to orange, which showed an efficient energy transfer from BODIPY to rhodamine. The probe can fast detect HOC1 in 15 s with the detection limit of 38 nM. Moreover, the probe can be applied to successfully monitor HOC1 in living RAW 264.7 cells with low toxicity and great light stability.