Optical And Electrochemical Sensing Properties Of Metal-tyrosine Coordination Polymers

Metal-organic coordination polymers?MOCPs?possess the rich spatial structure,large specific surface area,as well as unique optical,electrical,and magnetic properties,so they have become research hotspots in recent years and attracted the scientific researchers widespread attention.Most of MOCPs organic ligands contain aromatic,heterocyclic functional groups and are easy to luminescence under the excitation of ultraviolet and visible light,so most of MOCPs have been found to have photoluminescence properties.However,MOCPs materials in electrochemical aspects have been developed in recent years,still relatively less those on MOCPs' electrochemical sensing.Therefore researches of MOCPs materials in electrochemical sensing areas are relatively new.In this thesis,we synthesized amino acid-containing MOCPs and studied the UV-Vis,fluorescence and electrochemical properties.At the same time it was prepared as a novel non-enzymatic nitrite or hydrogen peroxide electrochemical sensors.The main contents are as follows:1.The optical properties and electrochemical sensing of the[Co_xZn_1-xtyr]_n coordination polymers were studied.Isomorphous substitution coordination polymers[Co_xZn_1-xtyr]_n synthesized under hydrothermal conditions by Metal cobalt,zinc salt which have variable valence and empty d orbitals and L-tyrosine.L-tyrosine owns coordinated diversity,chiral,fluorescent and biocompatibility.The synthesized CPs were characterized by XRD,EDS,UV-Vis DRS,fluorescence and CVs.XRD and EDS shows that we synthesized five different proportions isomorphic substituted coordination polymer[Co_xZn_1-xtyr]_n,while UV-Vis DRS also show different mixed metal[Co_xZn_1-xtyr]_n.Their UV-Vis DRS and fluorescence spectrum changed gradually along with the composition.CVs of modified electrodes[Co_xZn_1-xtyr]_n/GCE,showed that as more and more Zn replaced Co,the current signal decreased greatly and the potential shifts negatively.Much attention was paid to L-tyrCo due to its highest sensitivity and the L-tyrCo modified carbon paste electrode preparation was simple,cheap and renewed in its surface by simple polishing,so we studied to the electro-catalytic properties of L-tyrCo to nitrite by chronoamperometry.The electrochemical sensor has fast response time about 3-5 s.The linear detection range was from 5.0×10-5 to 3.45×10-3 M,with sensitivity of 263.4 mA mol^-1 L cm^-2.And the detection limit was found to be 2.0×10-5 M?S/N=3?.The sensor also showed good antiinterference and reproducibility.Under optimized conditions,rainwater was selected as real samples for analysis using the standard addition technique.The recovery of the spiked samples ranged between 94.6%and 105.0%,showing that the proposed method could be effectively used for the determination of nitrite in real samples.2.The preparation,characterization and properties of the[Cu₂?tyr?₂?bipy?]_n coordination polymer was discussed.We used copper salts which have variable valence and empty d orbitals,tyrosine,organic bridging ligand 4,4'-bipyridine and surfactant polyvinylpyrrolidone by adjusting different temperature,pH and synthesised micro-nano 2D sheet coordination polymers[Cu₂?tyr?₂?bipy?]_n under the conditions of constant temperature evaporation.The optimal synthesis temperature and pH were at 60 ?,about 4 respectively.The synthesized CPs were characterized by XRD,UV-Vis,fluorescence and CVs.XRD shows that we have successfully synthesized the same structure coordination polymers reported in the literature.The UV-visible absorption spectrum,fluorescence and electrochemical properties of the coordination polymers were studied.Electro-catalytic reduction of[Cu₂?tyr?₂?bipy?]_n CPE to H₂O₂ was studied by chronoamperometry.The enzyme-free electrochemical sensor have fast response time about 5 s,wide linear range 1.0 × 10-5 M-7.69 v 10-3 M,high sensitivity up to 85.6 mA moL^-1 L cm^-2,and the low detection limit 1.0 × 10-5 M?S/N=3?.That indicate that we successfully prepared an enzyme-free H₂O₂ electrochemical sensors,and it had a short response time,wide linear range,good stability and was cheap.