Synthesis And Application Of Porphyrin Based Covalent Organic Frameworks In Electroanalytical Chemistry

Due to some remarkable merits such as good crystallinity,periodic network structure,large specific surface area,high thermal stability,low density and so on,covalent organic frameworks?COFs?,have sidely been applied in multiple fields including gas storage and separation,photoelectric,supercapacitor,fluorescence,catalysis,and drug delivery.However,its application in electroanalytical chemistry has just started.In this thesis,four new COFs were designed and synthesized using the porphyrin derivative,with large?-electron conjugated planar structure,unique photoelectric properties and good thermal stability,as one of structural units and their structures and properties were characterized by scanning electron microscopy?SEM?,infrared spectroscopy?FT-IR?,X-ray photoelectron spectroscopy?XPS?,X-ray powder diffraction?PXRD?,thermogravimetric analysis?TGA?and N₂ adsorption and desorption experiments.Due to the structural characters of the monomers,the resulted COFs showed good conductivity and electrocatalytic activities and using them as the modified materials,the developed electrochemical sensors delivered excellent performances.This thesis mainly consisted of four parts as follows:1.ZnP-COF based on metal zinc porphyrin was designed and synthesized,and a new electrochemical sensor was constructed for determination of catechol?CC?and hydroquinone?HQ?by combining the excellent properties of ZnP-COF and graphene oxide?GO?.The electrochemical behaviors of CC and HQ on ZnP-COF/GO/GCE were investigated by differential differential pulse voltammetry?DPV?and cyclic voltammetry?CV?.The results showed that the ZnP-COF/GO/GCE modified electrode could be used to detect CC and HQ sensitively.Under optimization conditions,the oxidation peak currents of CC and HQ showed good linear relationships with their concentrations in the range of 4¹00?mol/L,100¹40?mol/L and 0.85¹00?mol/L,100¹40?mol/L,respectively.The detection limits were 1.24 and 0.38?mol/L?S/N=3?,respectively.At the same time,ZnP-COF/GO/GCE modified electrode showed excellent stability,reproducibility and anti-interference,and was a promising electrochemical sensor for simultaneous determination of these two analytes in real samples.2.CoP-COF based on metal cobalt porphyrin was designed and synthesized,and a novel electrochemical sensor was constructed by electropolymerization procedure for sensitive recogination of acetaminophen?AC?and p-aminophenol?AP?.The CoP-COF/GO/GCE modified electrode has a significant catalytic properties toward the redox reactions of AC and AP,the detection limits were down to 0.06?mol/L and0.18?mol/L,respectively?S/N=3?.In addition,CoP-COF/GO/GCE had great stability,reproducibility and anti-interference,and could be used for simultaneous determination of AC and AP in urine and tap water samples.3.Acyl chloride-functionalized multiwalled carbon nanotubes?MWCNTs-COCl?and PI-COF 201 which obtained with tetraaminophenyl porphyrin as building units,were selected as modified materials,a novel electrochemical sensor for simultaneous determination of guanine?G?,adenine?A?and acetaminophen?AC?was fabricated.The modified electrode not only had good electrocatalytic activities to the electrode reaction of G,A and AC,could but also distinguish these three target molecules.Under the optimization conditions,the oxidation peak currents and concentrations of A,G and AC showed good linear relationships in the range of 6.0¹00,4.0⁶0 and0.8¹00?mol/L,respectively.The detection limits were 4.23,1.75 and 0.48?mol/L?S/N=3?,respectively.4.A new 2D COF material PI-COF 301 based on tetraaminophenyl porphyrin was synthesized and used for preparing a sensitive electrochemical sensor PI-COF301/MWCNTs-COCl/GCE by a simple drop-casting method.The electrochemical behavior of uric acid?Uc?and dopamine?Da?on the modified electrode were investigated by CV and DPV methods.The results showed that PI-COF 301/MWCNTs-COCl/GCE had good electrocatalytic properties for Uc and Da and could be employed to detect these two analytes.Uc and Da showed good linear relationships between the oxidation peak currents and the concentrations in the concentration range of 0.9⁸8 and 2.8¹46?mol/L,respectively and the detection limits were 0.48 and0.96?mol/L?S/N=3?,respectively.The proposed method was sensitive,rapid and stable and it could be exploited to detect simultaneously Ua and Da in real samples.