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Studies On Synthesis And Properties Of Fluorescent And Colormetric Chemosensors Based On Schiff-base

Posted on:2013-12-11Degree:MasterType:Thesis
Country:ChinaCandidate:P P WangFull Text:PDF
GTID:2298330467953091Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
Three fluorescent and colorimetric chemosensors have been designed and synthesized for selective detection of Hg2+, I-, Cu2+and Al3+. In addition, these chemosensors could be used for detection and monitor the content of these ions, the results are listed as follows.1. A thiourea-based derived schiff base chemosensor,2,5-dimethoxy benzaldehyde thiose micarbazone (1), was synthesized by ball milling for15minutes at20Hz, which is a quantitative reaction. In buffered aqueous solutions, compound1displays a sensitive turn-off fluorescence response to Hg(Ⅱ) and exhibits extreme specificity toward Hg(Ⅱ) even in the presence of20-fold concentrations of other competitive metal ions such as K+、Mg2+、Ca2+、 Zn2、Cu2、Co2+、Ni2+、Fe3、Mn2+、Cd2+、Cr3+and Pb2+. It provides the detection limit of1.85×107mol/L for Hg(Ⅱ). The anion recognition behavior of the mercury complex1-Hg has been studied in aqueous solutions.1-Hg shows high selectivity toward iodide ion over other anions studied such as F-,Cl-,Br-,NO3-, SO42-and AcO-. And the mercury complex1-Hg shows a detection limit of1×10-7mol/L for iodide ion. Of note, compound1can be utilized as a sequential fluorescence probe for Hg2+and I-for many times, which show high stability in aqueous solutions.2. A new rhodamine hydrazone derivatives probe2-(3,6-Bis-diethylamino-8a,10a-di-hydro-3H-xanthen-9-yl)-benzoic acid (2-hydroxy-3-methoxy-benzylidene)-hydrazide(2), which is highly sensitive and selective colorimetric chemosensor for Cu2+ions, have been designed and synthesized. As the coordination bond between2and Cu2+forms, the color of the mixture changes from colorless to red very quickly. Compound2exhibits a high sensitivity and selectivity for Cu2+, comparatively, other metal ions such as K+、Mg2+、Ca2+、 Zn2+、Co2+、Ni2+、Fe3+、Mn2+、Cd2+、Cr3+、Hg2+、Pb2+are not. Moreover, it exhibits a stable response to Cu2+from1.0×10-7to1.0×10-6mol/L, with a detection limit of1.0×10-7M. More importantly,2could be used as a real chemsensor for Cu2+in our daily life, when a test paper soaked with2is made.3. A novel shciff-based sensor,2-Hydroxy-benzoic acid (2,4-dihydroxy-benzylidene)-hydrazide (3), is obtained as a highly sensitive and selective colorimetric turn-on fluorescent chemosensor for Al3+ions. Compound3, which is soluble in water, exhibits a remarkably "turn on" response toward Al3+over other metal ions such as K+、Mg2+、Ca24、Zn2、Cu2+、 Co2+、Ni2+、Fe3+、Mn2+、Cd2+、Cr3+、Hg2+、Pb2+. For3, there is a50-fold fluorescence enhancement when Al3+is added, and it shows a detection limit of1×10-7mol/L for Al3+.
Keywords/Search Tags:Fluorescence, Colorimetric, Chemosensor, Mechanochemistry, Schiff-base
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