Application Of Functional Metal Organic Framework Compounds In Electrochemical Analysis

Metal-organic frameworks (MOFs) are infinite crystalline networks resulting from the bonding of metal ions, which act as coordination centers, with polyfunctional organic molecules. As a result, they are stable nanoporous materials with high mechanical and thermal stability. Applications of MOFs for catalysis, gas storage, and separation are the focus of considerable research. In this paper, metal-organic framework was proposed for analytical purpose, and the main study includes three parts:1、Construction of an electrochemical sensor based on amino-functionalized metal-organic frameworks for differential pulse anodic stripping voltammetric determination of leadHerein, amino-functionalized metal-organic frameworks (NH2-Cu3(BTC)2; BTC= benzene-1,3,5-tricarboxylate) was prepared and used as a novel electrode modifier for the determination of trace levels of lead. NH3-Cu3(BTC)2 shows quite a good capability for the efficient adsorption of lead from aqueous solutions. The parameters affecting the electrochemical process, such as electrolyte solution pH. the amount of NH3-Cu3(BTC)2 suspension, accumulation potential and accumulation time, were investigated in detail. Under the optimal conditions, the electrochemical sensor exhibited a linear response to the concentration of lead in the range of 1.0× 10-8 to 5.0 × 10-7 mol L-1 (R2= 0.9951) with a detection limit of 5.0 × 10-9mol L-1. The relative standard deviation of 11 successive scans was 3.10% for 1.0 × 10-8 mol L-1 lead. The method was validated with certified reference material (stream sediment and milk powder) and the analytical results coincided well with the certified values. Furthermore, the method was successfully applied to the determination of target analytes in tap and lake water samples and good recoveries were obtained from different spiked values.2、Carbon functionalized metal organic frameworks/nafion composite as novel electrode materials for ultrasensitive determination of dopamineCarbon functionalized metal organic frameworks (C/Al-MIL-53-(OH)2) were successfully prepared for the first time by solvothermal technique and characterized by Fourier transform infrared spectroscopy. X-ray diffraction spectrometry, and scanning electron microscopy. This composite was coated with nafion film so as to form nafion/C/Al-MIL-53-(OH)2 modified glassy carbon electrode. The modified electrode was then used as a novel electrocatalyst for dopamine (DA) oxidation in phosphate buffer solution. Due to the synergistic effects of the different materials, including the high conductivity of carbon, large surface area of Al-MIL-53-(OH)2, and the film-forming ability of cation-exchange polymer, the modified electrode exhibited a remarkable enhancement effect on voltammetric response of DA. Under the optimal conditions, the response peak currents had linear relationship with DA concentration in the range from 3.0× 10-8 to 1.0 × 10-5 mol L-1. The limit of detection and quantitation for DA were found to be 0.8× 10-8mol L-1and 2.6 × 10-8mol L-’. respectively. The analytical utilities of the proposed biosensor were achieved by analyzing the content of DA in biological fluids.3、Fabrication of nano-gold particles coated, amino-functionalized metal organic frameworks for the electrocatalytic oxidation and voltammetric determination of bisphenol AA novel biosensor has been constructed by the immobilization of Au-nanoclusters (nano-Au) on amino-functionalized metal-organic frameworks (NH2-MIL-53(Al)) modified glassy carbon electrode (GCE) and employed for the determination of bisphenol A (BPA). The Au/ NH2-MIL-53(Al) material exhibits excellent electrocatalytic activity for the oxidation of BPA by substantially enhancing the current response and decreasing the BPA oxidation overpotential. The composite modified glass carbon electrode (GCE) exhibited good performance for detecting BPA due to the enhanced electron transfer kinetics and large active surface area. Under the optimized conditions and according to the results from differential pulse voltammetry(DPV), the BPA oxidation current is linear in a concentration range of 10-7 mol L-1 to 10-5 mol L-1, and the detection limit was determined to be 4.65 × 10-8 mol L-1. The proposed sensors were successfully employed to determine BPA in real plastic products, and the recoveries were between 96.8 and 107.6%. This strategy might enable more opportunities for the electrochemical determination of BPA in practial applications.