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Study On Electrochemical Sensors Based On Chiral Salen Metal Complexes

Posted on:2012-08-02Degree:MasterType:Thesis
Country:ChinaCandidate:B X LiFull Text:PDF
GTID:2131330335456878Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
The study of electrochemical sensors has become a very important topic in analytical chemistry, which has been widely used in food analysis, biomedical detection, environmental monitoring and other fields due to its fast response, good selectivity, simple equipment and operation, low cost and high sensitivity, etc. In this paper, the electrochemical sensors were applied in recognition of chiral mandelic acid and detection for formaldehyde. To design and synthesize chiral Salen and its metal complexes are very vital for the developed electrochemical sensors with good selectivity, chiral Salen-Cu(II), Salen-Co(III) and Salen-Co(II) complexes have been synthesized and the electrochemical sensors were fabricated by using these compounds as recognition elements. Meanwhile, the sensor constitution, performance, selectivity and response mechanism were investigated. The main contents are as following:1. Chiral (R,R)-N,N'-bis(3,5-di-tert-butylsalicylaldehyde)-1,2-diaminocyclohexane copper complex [Salen-Cu(II)] was synthesized by 3,5-di-tert-butylsalicylaldehyde and (1R,2R)-diaminocyclo-hexane, which was prepared as the carrier of enantioseletive PVC membrane electrode (Salen-Cu /PVC). Due to the different stabilities of ligand complexes, which were formed by Salen-Cu(II) compound coordinating with chiral enantiomeric mandelic acid(R-MA or S-MA), the electrode can preferentially respond to R-mandelic acid, exhibiting near Nernstian response of-52.1 mV/dec in the concentration range from 1.0×10-4 to 1.0×10-1mol/L with a detection limit of 6.0×10-5mol/L and the enantioselectivity coefficient logKR,SPot,-2.17.2. Chiral (R,R)-N,N'-bis(3,5-di-tert-butyl salicylaldehyde)-1,2-diaminocyclohexane cobalt complex [Salen-Co(III)] was employed as the chiral selector of PVC membrane electrode, which was synthesized via 3,5-di-tert-butyl salicylaldehyde and (1R,2R)-diaminocyclohexane. Under the optimized conditions, the selective PVC membrane electrode was prepared by uniformly mixing the carrier, plasticizer and PVC powder in a certain percentage (Salen-Co/PVC). Attributed to the different stabilities of ligand complexes that was formed by coordinated bond between Salen-Co(Ⅲ) compound and chiral enantiomeric mandelic acid(R-MA or S-MA), the electrode displayes near Nernstian slope of -55.7 mV/dec in a linear range of 1.0×10-4 to 1.0×10-1 mol/L for R-mandelic acid with a detection limit of 2.0×10-5 mol/L and an enantioselectivity coefficient logKR,SPot,-2.36.3. Chiral (R,R)-N,N'-bis(3,5-di-tert-butyl salicylaldehyde)-1,2-diaminocyclohexane cobalt complex [Salen-Co(II)] has been used as a chemical modifier, which was synthesized via 3,5-di-tert-butyl salicylaldehyde and (1R,2R)-diaminocyclohexane. Salen-Co(II) modified carbon paste electrode (Salen-Co/CPE) have been fabricated by directly mixing of chemical modifiers, paraffin oil and graphite powder in proportion. The devoleped electrode exhibits a good electrocatalytic activity for formaldehyde by chronoamperometry and a linear range from 3.0×10-2 to 1.2×10-1mol/L with the detection limit of 3.33×10-3mol/L were obtained.
Keywords/Search Tags:Modified Carbon Paste Electrode, Selective PVC Membrane Electrode, Chiral Salen Metal Complexes, Chiral Mandelic Acid, Formaldehyde
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