Design, Synthesis, And Application Of BODIPY–Based Fluorescent Probes For Mercury Ion And Biological Thiols

As opposed to various traditional analytical methods, fluorescent probes as a novel biological detection method, which is focused on by the market and researchers, has the following advangtages: the simplicity, good selectivity, high sensitivity, low cost, and easy application to environmental and biological systems for fluorescent technique. Since Treibs found it, boron-dipyrromethene?BODIPY? fluorescent dyes has been widely used in the labeling reagents, fluorescent switches, chemosensors, and laser dyes, because of their outstanding characteristics, such as high molar absorption coefficients, intense fluorescence quantum yield, valuable photo- and chemo- stability, easy modifications to the structures and exceptional insesititivity to the polarity of solvents as well as to pH. 8-position?meso position? of BODIPY has been demonstrated to be most sensitive position for fluorescent probes, which has been finely tuned for the emission maxima and fluorescence quantum yield by the electronic nature of the substituent. Based on the past research of our group and the literature investigation, we are interested in the modification of 8-position with O-, N-, S- symmetrically and unsymmetrically to change the photo physical properties of BODIPY and study the application in the probe.In the second chapter,we synthesized three probes based on meso-Cl, and emphasizly discussed the differences in steric hindrance upon addition of the methyl moiety effected the solvent effect, reaction activity and the stability of the probe. When BDP2 encountered with Cys/Hcy, firstly, thiol attack eight carbon and hydrogen chloride molecule was to leave leave, generating dynamic controlled product. And then amino cyclized to the eight carbon to give a thermodynamic control product with the release of the blue fluorescence. Due to GSH molecular skeleton was larger and amino is far away from sulfydryl group, the product of the reaction of probe with GSH also stays in thiol phase and release the green fluorescence. At the same time, ratiometric fluorescent probe may also increase the dynamic range of fluorescence measurement, and can also provide more accurate results. In addition, the probe was also carried out for detecting cysteine in human plasma, which reflected the potential application in biological sample analysis.Next, utilizing BODIPY as fluorophore and a nitroazo group as functional group, we designed and synthesized a highly selective turn-on fluorescent chemosensor for Cys/Hcy and GSH. The probe made use of dual emission channels for sensitive discrimination of Cys/Hcy and GSH, and could distinguish monitor Cys/Hcy and GSH.Last but not least, utilizing BODIPY as fluorophore and thiourea as functional group, we designed and synthesized a highly selective turn-on fluorescent chemosensor for Hg²⁺. Reacting 8-chloro-BODIPY in DMF with N-aminoethyl-N'-phenyl thiourea prepared from ethylene diamine and phenyl isothiocyanate afforded the desired probe. The probe displayed selective response to Hg2+, and the likely sensing mechanism was proposed as Hg2+ promoted cyclization and subsequent hydrolysis. Additionally, experiments with living Human Hepatoma SMMC-7721 cells to visualize intracellular Hg2+ in biological systems were carried out with the probe.