Design, Synthesis And Application Of Several ESIPT-Based Copper Ions Fluorescent Probes

The fluorescent probes have been considered as ideal tools that can monitor and image trace amounts of metal ions in live cells or environment due to its high sensitivity and sensitivity, operational simplicity, and real-time and nondestructive imaging properties. Excited-state intramolecular proton transfer(ESIPT) is a special excited light physical process,and the organic molecules based on ESIPT process were favourable fluorescence probe or photochromic materials due to have the large Stokes shift, optical bistable and phototropy. In this thesis, we focus on constructing a serial of novel copper ions fluorescent probes using imidazole-based phenanthrenequinone derivatives(HPI), benzothiazole derivatives(HBT), and the combination by two derivative as fluorophores. The concrete contents are as follows:(1) Two novel ESIPT-style fluorescent probes, Pi-A and Pi-E, were designed and synthesized using imidazole-based phenanthrenequinone derivatives(HPI). The favorable features of the proposed probes including excellent water solubility, wide pH range, high selectivity and sensitivity to Cu2+. Interestingly, the difference in the linker of the probe molecules led to radical change in the fluorescent response of the probes to Cu2+. Pi-A showed fluorescence turn-off while Pi-E showed fluorescence turn-on when react with Cu2+ respectively in the same condition. The Cu2+ recognition mechanisms of the probes were investigated by Job’s plot analyses, NMR and ESI-MS spectroscopy experiments. Moreover, our experiments also showed that the probes are of excellent cell permeability and are capable of fluorescent imaging Cu2+ within living cells.(2) We have synthesized four ESIPT-type fluorescent organic compounds based on benzothiazole derivatives(HBT), namely controled HBT, BM, probe BT and product BA, and studied their spectra properies and responding mechanism to Cu2+. Upon addition of Cu2+, the complexation heteroatomic N and hydroxyl group with Cu2+, so the ESIPT process was inhibited which led to a fluorescence quenching of probe BT. According to Job’s plot, the stoichiometry in the reaction of probe BT with Cu2+ was 1:1. Moreover, probe BT exhibited quick response, high selectivity and sensitivity to Cu2+ detection.(3) We have inroduced a new strategy to construct a unique class of ESIPT-based copper ions fluorescent probe, probe CK, combined imidazole-based phenanthrenequinone derivatives(HPI) with benzothiazole derivatives(HBT). There are a series of research about spectra properies and water solubility of probe CK, and sensitivity to Cu2+ detection. Addition of Cu2+ to probe CK can inhibit the ESIPT process and induce obvious fluorescence quenching. Probe CK have many advantages including low detection limit and short response time, high sensitivity and selectivity to Cu2+.