Preparation And Study Of Fluorescent Probe Towards Mercury And Copper Ions

With the vigorous development of the industrialization process,pollution of heavy metal ions has been a long-lasting threat to the environment and human health.And some important trace metal elements generally play indispensable roles in the regulation of human body.Therefore,it's of great significance to develop a method which can effectively detect metal ions.Based on the distinct properties,fluorescent probe molecules were applied to selectively recognize metal ions in this thesis.Coumarin derivatives and rhodamine B with excellent photophysical properties were selected to connect 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate which contained multiple heteroatom binding sites,thus designing two novel fluorescent probes CBH and RBH,respectively.Firstly,the structures of the probes were characterized by NMR,MS and X-ray single crystal diffraction structure analysis.The recognition properties and processes were studied through a series of spectra analysis subsequently.The probe CBH could selectively recognize mercury ions.In the presence of mercury ions,it showed 4-fold fluorescence increase at 530 nm compared with that of free CBH and the fluorescence intensity at 530 nm showed a good linear relationship against concentrations of mercury ions ranging from 15 to 40 ?M.Meanwhile,absorbance at 470 nm was enhanced upon addition of mercury ions.Other metal ions could not induce these changes and the recognition of mercury ions by CBH could not be disturbed by other common metal ions.The probe and mercury ions were bound in the form of 1: 1 with a binding constant of 3.89×105 M-1.Further analysis demonstrated the high sensitivity of CBH for mercury ions and the mercury ions could be detected linearly at the ppb level.It revealed that the probe CBH can selectively recognize mercury ions with high sensitivity.The probe RBH displayed high selectivity towards copper ions and the recognition of copper ions by the probe RBH could not be disturbed by other coexisting metal ions.After addition of copper ions,the fluorescence emission exhibited an “off-on” response and the fluorescence intensity at 580 nm was enhanced with the rising concentration level of copper ions.It showed a 132-fold fluorescence enhancement ultimately.Simultaneously,it exhibited an emerging absorption peak at 570 nm and the absorbance was enhanced with the increasing concentration of copper ions,along with a color change from colorless to purple.The addition of copper ions resulted in the ring opening of the rhodamine group and the binding constant was 1.36×105 M-1.RBH towards copper ions had high sensitivity and the copper ions could be linearly detected at the nanomolar level.The interaction of RBH with copper ions was very rapid and RBH could effectively determinate copper ions at a certain pH range including physiological pH.The laser confocal imaging of A549 cells suggested that the probe RBH can potentially recognize copper ions in living cells.