Syntheses And Applications Of Several Fluorescent Probes

Molecular probe is a tool that can transfer the molecular recognition events into the optical signals. Because of its high sensitivity, specific selectivity, simple operation, low cost, free from outside influence of electromagnetic fields, distant luminous and other advantages,fluorescent probe is widely used in pharmaceutical, chemical, biological sciences and other fields. In this thesis, fluorescent probes for cysteine/homocysteine, hydrazine and nitroreductase(NTR) are synthesized respectively. As follows:(1)A new probe of 4-(1-(4- methoxyphenyl)-4,5- diphenyl-1H- imidazole-2-) benzaldehyde(MPI-CHO) was designed and synthesized. The probe was characterized by using Mass Spectrometry(MS) and Nuclear Magnetic Resonance(NMR). Upon the addition of cysteine and homocysteine, the emission spectrum of the fluorescent probe exhibited a large emission wavelength shift(about 102 nm) and a ratio of fluorescence. The probe can be used to quantitatively and distinctively detect Cys/HCys according to different response time and fluorescence intensity.(2)A novel ratiometric fluorescent probe, 2-(benzo[d]thiazol-2-yl)phenyl-4-oxopentanoate(HBT-RCO) for hydrazine was rationally developed based on the excited state intramolecular proton transfer process(ESIPT). The probe was characterized by using Mass Spectrometry(MS) and Nuclear Magnetic Resonance(NMR). Moreimportant, the emission spectrum showed a ratio response toward hydrazine. Significant red shift(98 nm) was observed with the emission peak in the presence of hydrazine and the emission ratio value(I483/I385)enhanced to approximately 14 times. Using the synthesized probe, the detection of hydrazine can be realized.(3) Based on the specificity catalysis reduction mechanism of nitroreductase which can reduce aromatic nitro compounds, a novel turn-on fluorescence probe(TPN-NO2) was designed and synthesized.This probe is based on the principle of Intramolecular Charge Transfer(ICT). First, the probe was weakly fluorescence intensity. While adding nitroreductase aromatic nitro compounds were reduced to a hydroxylamine, the molecular structure of the probe was changed.Because of the electronic push–pull system changed the fluorescence intensity was enhanced within the process of "ICT-on". The probe exhibited good selectivity and very high sensitivity toward nitroreductase with a detection limit of 0.2 ng/mL, what is more, it can be applied to naked-eye colorimetric detection.