Synthesis, Structure Characterization,Optical Properties And Application Of Fluorescent Probes Based On Pyrazoline

Zinc ion plays an indispensable role in many biological processes, such as neurotransmission, catalytic functions of proteins, gene expression, pathology, cell apoptosis, metallo enzyme function. Copper ion, as an essential trace element, also plays a critical role in regulating various biological processes such as acting as a catalytic cofactor for a variety of metalloenzymes including superoxide dismutase, cytochrome c oxidase, and tyrosinase. In addition, excess amount of Cu may do harm to liver or kidney damage, while deficiency of copper could be causative in coronary heart disease. Therefore, the quantification and qualification of zinc or copper is of great importance in the biological or environmental systems. Fluorescence probes are powerful tools to monitor metal ions owing to their simplicity and high response speed, and have attracted considerable interest to apply in biological system with high selectivity and sensitivity.Pyrazoline derivatives are important organic compounds which contain nitrogen5-membered heterorcyclic. And these compounds have been reported to possess a wide range of biological activities, such as antimicrobial, antinociceptive, anticancer. Recently, fluorescent probes based pyrazoline derivatives have attracted much attention because of their excellent photophysical property, including blue fluorescence property, the high fluorescence quantum yield, good stability, membrane permeability, and low toxicity.Since the important application of pyrazoline derivatives in the fields of medicine and metal ion probes, we designed and synthesized three pyrazoline fluorescent probes for Zn (Ⅱ) and Cu (Ⅱ). We pay attention on the study of optical property and applied to detect Zn2+in cells. The main contents are summarized as follow:1. Synthesis, characteristics and application of1-(3-(5-chloro-2-hydroxyphenyl)-5-phenyl-4,5-dihydro-lH-pyrazol-l-yl)ethanone as probe for Zn2+.To gain the target product, we firstly synthesized chalcone by using1-(5-chloro-2-hydroxyphenyl)ethanone and benzaldehyde, then, reacted with hydrazine hydrate under reflux in acetic acid. The structure of the compound was determined by IR, NMR, HRMS and X-ray analysis. The optical properties of the probe was investigated, through the study, we found that the probe L can monitor Zn2+ion in aqueous solution with good selectivity and sensitivity. The stoichiometric ratio between the probe L and Zn2+was determined by Job’s plot and found to be1:1. This new probe is cell-permeable and can be successfully used to image intracellular Zn2+in SH-SY5Y cells.2. Synthesis, characteristics and application of1-(3-(1-hydroxynaphthalen-2-yl)-5-phenyl-4,5-dihydro-lH-pyrazol-1-yl)ethanone as probe for Zn2+.A novel fluorescent probe based on naphthalene pyrazoline fluorophore for Zn2+was designed and synthesized. The structure of the probe was characterized by IR,1H NMR,13C NMR, and HRMS spectra. The probe can induce a significant enhancement after Zn2+was added and exhibits high sensitivity and selectivity for response to Zn2+in EtOH/HEPES solution. The excitation wavelength of the probe was410nm which is in the visible light region. The probe showed good reversibility upon addition of EDTA or TPEN. Furthermore, the probe L was successfully applied to monitor Zn2+ions in living HeLa cells.3. Synthesis, characteristics as Cu2+probe of1-(3-(5-chloro-2-hydroxyphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-y1)-2-phenylethanone.We firstly synthesized4-chloro-2-(5-phenyl-4,5-dihydro-1H-pyrazol-3-y1)phenol by using chalcone and hydrazine hydrate under reflux in ethanol, then, reacted with phenylacetyl chloride in acetonitrile to obtain the target product. The structure of probe was determined by IR, NMR, and HRMS. And the fluorescence intensity was sharply decreased when Cu2+was added to EtOH/HEPES solution of probe L with a very fast speed. The binding mode of L-Cu2+was1:1which was confirmed by Job’s plot. Moreover, the detection limit was calculated to be3.53×10-7M. The probe shows good water solubility and can monitor Zn2+with good selectivity and sensitivity.