The Synthesis And Properties Investigation Of Coumarin And Carbazole Based Probe

Silver ion and mercury ion,as heavy metal ions,are among the most poisonous categories of toxic ions.Repeat silver exposure to human body may cause argyria and urine silver excretion,cardiac enlargement,growth retardation and degenerative changes.And long-term accumulation of insoluble precipitates of Ag+ compounds may damage skin and eyes.The widespread use of mercury and silver also can cause potential hazards to our environment.Therefore,detection of the biologically and environmentally important ions(such as Hg2+,Hg+),has emerged as asignificant goal in the field of chemosensor in recent years.Probe moleculars(via UV-vis absorption or fluorescence changes)can convert the recognition information into a perceived optical sigal.These probe have received considerable attention,due to the high sensitivity,rapid detection and low detection limit.In this thesis,probe moleculars based on coumarin and carbazole as the signaling group for Ag+and Hg2+ were designed and synthesized.The details are listed as following,In chapterl,Structures and the basic mechanisms of chemosensor are mainly described,and research progresses of chemosensors for Hg2+ and Ag+ are briefly reviewed.Then the research subject of this dissertation is proposed.In chapter 2,Probe S1 based on coumarin as the chromphore and dithia-dioxa-monoaza crown ether moiety as the recognition site for Ag+was designed and synthesized.The sensing properties of S1 were investigated by UV-vis.Upon the addition of silver ion to the EtOH-H2O solution(1:1,v/v)containing S1,the blue-shift of the maximum absorption wavelength and the decrease of molar absorption coefficient were observed.However,when the other ions were added,such as Mn2+,Co2+,Ni2+,Cu2+,Al3+,Ca2+,Cd2+,Cr3+,Ba2+,Hg2+,Sr2+,K+,Mg2+,Li+,Fe3+,Pb2+ and Zn2+,the maximum absorption wavelength and molar absorption coefficient did not show obvious change.These results showed that S1 has a good selectively sensing ability for Ag+.In chapter 3,A carbazole-baesed water soluble probe S2 was designed and synthesized.The detection limit of the sensor for Hg2+ is about 1.12×10-8 M.Probe S2 showed high selective detection of Hg2+ in pure water solution by the the mercury-promoted transformation of a dithiane group into an aldehyde functional unit.The mercury-promoted transformation was confirmed by 1H NMR spectra analysis.