The Design And Synthesis Of Near-Infrared Ratiometric SO₃^2- Probe And Two-photon Pd Probe And Research Of Their Spectral Properties And Biological Application

Recently, fluorescence imaging has emerged as one of the most powerful techniques to monitor targets and biological processes in the context of a living system with high temporal and spatial resolution. Thus, fluorescence imaging is invaluable for studies in diverse fields ranging from biology, clinical diagnosis, to drug discovery. Fluorescent probes are essential molecular tools for bioimaging as they exhibit the advantages of high sensitivity and simplicity for implementation. From herein, "analyte-responsive fluorescent probes" are briefed as "fluorescent probes". To date, a large volume of fluorescent probes for a wide variety of targets have been developed. However, most of them have the absorption and emission in the ultraviolet-visible (UV/Vis) light range, which renders them difficult to be employed for sensing and imaging targets of interest in living animals, as the absorption and autofluorescence of biomolecules in the UV/Vis region are high. By contrast, probes with absorption peak and emission peak in near infrared region (650-900 nm) and two-photon microscope (TPM) can solve this problem very well. NIR fluorescent probes are favorable for in vivo bioimaging because of minimum photo-damage to biological samples, deep tissue penetration, and minimum interference from background auto-fluorescence by biomolecules in the living systems. For two-photon excitation fluorescence (TPEF) microscopy, the fluorescence is triggered by spatially confined two-photon excitation, bears several advantages over the conventional one-photon fluorescence microscopy, including three-dimensional imaging of living tissues, reduced photodamage to biosamples, increased tissue penetration, and negligible background fluorescence. However, small-molecule NIR fluorescent probes and two-photon fluorescent probes are very challenging to be constructed and Thus, innovative strategies for development of NIR and two-photon fluorescent sensors are actively sought after.In Chapter I, we have syntheized a new class of NIR fluorescent dyes, which are both absorption and emission in the NIR region while retaining an optically tunable hydroxyl group. This unique feature can be exploited for development of NIR fluorescent sensors for living animal imaging applications. And, a innovative NIR fluorescent sensors for Sulfite was constructed.In Chapter II, We have rationally constructed the first two-photon fluorescence Pd(?) probe, based on a GCTPOC fluorescent dye and deprotection of aryl propargyl ethers by palladium. The probe GCTPOC-Pd displayed a 100-fold enhancement turn-on to palladium with high sensitivity and selectivity. Additionally, the novel GCTPOC-Pd probe is the first suitable for fluorescence imaging of Pd in living tissues.