Design And Synthesis Of Novel F^-and H₂S Fluorescent Probes And Their Bioimaging

Fluorescence sensing is particularly appealing because of its simplicity, highsensitivity and excellent selectivity. Furthermore, fluorescence sensing is potentiallyapplicable for bioimaging in living cells with high temporal and spatial resolution.With the development of fluorescent spectroscopy and fluorescent imagingtechnology, fluorescent probe has played a significant role in a variety of fields, suchas biotechnology, environmental science, material science and biological medicine,and thus, the research on fluorescent probe has been widely developed. Recently,researchers have become interested in the development of two-photon dyes andtwo-photon fluorescent probes. Two-photon microscope (TPM) provides an attractivetechnique to study biomolecules in living cells and tissues. TPM, where fluorescenceis triggered by two-photon excitation, shows a variety of advantages. It can facilitatethree-dimensional imaging of living tissues, reduce photodamage to biosamples,increase tissue penetration, lower background fluorescence, which contribute to thecapability of imaging in deep tissues and animals. However, it is still a big challengeto find fluorescent probes with favorable properties and significantly large two-photonaction cross-section.In the second chapter of this thesis, we design and synthesize a novel probe todetect fluoride based on the excellent photophysical properties of phenanthreneimidazole and the mechanism of the formation of hydrogen bond between N-H bondand fluoride. The results of spectral research demonstrate that probe1response is afast-responding and highly selective system towards fluoride anions.In the third chapter, we design and synthesize a fluorescence “turn-on” probeCC-H2S to detect hydrogen sulfite on the basis of excellent properties of coumarin,such as larger stokes shift, the highly stable and tunable photophysical properties. Wereport the nucleophilic substitution of hydrogen sulfite with fluorescent probeCC-H2S, leading to dose-dependent “turn-on” fluorescence. The research onfluorescent and absorption spectra of the probe indicates that the fluorescent probeCC-H2S is expected to detect hydrogen sulfite in living systems.There are a number of merits about two-photon absorption where the excitationwavelength of two-photon absorption（TPA） is in the NIR region (600~900nm),such as lower photodamage and phototoxicity, deeper penetration, less excitationbackscattering effects and interference caused by background fluorescence. Therefore, in the fourth chapter, we synthesize a novel two-photon fluorescent probeGCTPOC-H2S to detect hydrogen sulfite based on H2S-induced thiolysis ofdinitrophenyl ether chemistry. The probe elicits significantly large fluorescenceenhancement (up to120-fold) after the addition of H2S to the probe, much larger thanthe previously reported two-photon probes for H2S. Most importantly, we demonstratethat GCTPOC-H2S has the capability of imaging H2S both in living cells and intissues with excellent sensitivity, high selectivity, as well as low cytotoxicity.