Synthesis And Characterization Of Metalloporphyrin Coordination Polymers And Their Electrochemical Sensors

Metal-Organic Frameworks(MOFs)possess large specific surface area,the rich spatial structure,and mutil-functionality.They have become a research hotspot in recent years which attracted scientific researchers' widespread attention.Metalloporphyrinic frameworks(MPFs),constructed from porphyrin or metalloporphyrinic building blocks,is a special MOFs material.It not only has the pore structure and large specific surface area of MOFs,organic ligands and metal ions are easy to achieve functional characteristics,but also it possess chemical properties and unique biological,are emerging as very promising functional materials for luminescence,gas adsorption and catalysis because of their unique properties and the permanent porosities provided by the functional porphyrinic building blocks.Bulk crystals of MOFs comprise porphyrin molecules as building blocks and their highly selective adsorption and catalytic properties have been reported.However,the electrochemical study of metalloporphyrinic frameworks is still rare.In this thesis,we synthesized a new metalloporphyrinic polymer,and prepared a novel bifunctional electrochemical sensor.The main contents are as follows:1.The preparation and characterization of Cu-CoTCPP.The metalloporphyrinic frameworks were prepared by copper salt,cobalt salt and biological molecules CoTCPP.Copper salt and cobalt salt which own the empty d orbital,valence state and unsaturated metal sites.While we have studied the effects of reaction conditions(reaction temperature,solvent,reaction time),the results showed the solvent were DMF and HNO3,then heated at 65? for one week.Cu-CoTCPP was synthesized by solvothermal method and characterized by various techniques,including XRD,IR,UV-vis,elemental analysis,TGA,and TEM.The XRD result indicates that Cu-CoTCPP has the layered structures which similar to CoTCPP-py-Cu(NAFS-1)with the similar plane and different interlayer spacing.According to the results of TGA and the elemental analysis,we conclude the formula is[Cu2(Co-TCPP)(H2O)2]·0.5DMF·5H2O.Electron microscope images show that particles are composed of stacked sheets.The sample well dispersed and no obvious agglomerations were found.2.Cu-CoTCPP/GCE and Cu-CoTCPP/MWCNTs/GCE were used to construct hydrogen peroxide and nitrite electrochemical sensors.Cu-CoTCPP/GCE showed novel bifunctional electrocatalytic ability toward the reduction/oxidation of H2O2 and the oxidation of NaNO2 which might be due to Cu and Co,respectively.-0.25 V(0.85 V)was chosen to obtain good performance for reductive(oxidative)determination of H2O2 the linear range was 7.0×10-5?4.71×10-3 mol/L(5.8×10-5?1.56×10-2 mol/L),the detection limit was 2.5×10-6 mol/L(5.8×10-5 mol/L)and the sensitivity was 28.5 mA mol-1 L cm-2(4.23 mA mol-1 L cm-2).0.85 V was chosen to obtain good performance for oxidative determination of NO2-,the linear range was 3.5×10-5?5.5×10-3 mol/L(R=0.997),the detection limit was 5.0×10-6 mol/L and the sensitivity was 15.32 mA mol-1 L cm-2.With the assistance of multi-walled carbon nanotubes(MWCNTs),Cu-CoTCPP showed improved sensing performance.The good performance for determination of H2O2 was obtained at-0.25 V with a detection limit of 5.0×10-7 mol L-1 and sensitivity of 168 mA mol-1 L cm-2 in linear range of 5.0×10-7?1.8×10-4 mol L-1,meanwhile the good performance for determination of NaNO2 was obtained at 0.85 V with a detection limit of 2.5×10-6 mol L-1 and high sensitivity of 439 mA mol-1 L cm-2 in linear range of 2.5×10-6?1.1×10-3 mol L-1.Cu-CoTCPP/MWCNTs/GCE also showed fast response,and high selectivity,steadiness and reproducibility.The bifunctional electrocatalytic ability and the excellent performance imply that the metalloporphyrinic frameworks are promising candidates for using in electrochemical sensing.3.The nitrite electrochemical sensors based on CoTPyP/CPE.CoTPyP were prepared by cobalt salt and biological molecules TPyP.CoTPyP was synthesized by solvothermal method and characterized by XRD and TEM.The XRD result indicates that the prepared CoTPyP has the same structure with the reported[Co(TPyP)]6·12CH3COOH·12H2O.TEM image shows that the synthesized sample is irregular particles.The width of the sample is 200?500 nm and the length of it is 0.5?2.0 ?m.Then we made CoTPyP carbon paste electrode to study electro-catalytic oxidation of NaNO2.The developed nitrite electrochemical sensor showed a high sensitivity of 743.3 mA mol-1 L cm-2 and a fast response time,which demonstrates that CoTPyP has a great potential in the application of electrochemical sensors.