| Compared with other electrode concepts in electrochemistry, the distinguishing feature of a chemically modified electrode (CME) is that a quite thin film (from monomolecular to perhaps a few micrometers in thickness) of a selected substance is bonded to or coated on the electrode surface to endow the electrode with the chemical, electrochemical, optical, electrical and other desirable properties of the film in a rational chemically designed manner. In this paper, a novel CME was designed by using LB technique, the main work and results are summarized as following:1. A glassy carbon electrode modified with Langmuir film of p-tert-butylthiacalix[4]arene (TCA) (including Cu2+) was successfully prepared and its electrochemical properties were studied by using several electrochemical methods. The electrode reaction process was investigated and some kinetic parameters were obtained. At the same time, the coordination number of the complex was also calculated according to the surface coverage of redox active species and the area of per molecule on electrode surface.2. A new type of current sensor, LB film of TCA modified glassy carbon electrode, was advanced and used for determining copper at trace levels by differential pulse stripping voltammetry. Calibration plot was found to be linear in the range of 2×10-8 mol/L to 5×10-6 mol/L with the detection limit of 2×10-9 mol/L. Possible recognition mechanism was also discussed. From the analysis of real samples (river, lake and tap water), it can be concluded that the method is rapid, sensitive in determining of copper and can be used in the analysis of natural water samples.3. A glassy carbon electrode modified with LB film of TCA has been investigated as a disposable sensor for measuring the trace levels of lead and cadmium. The possibility of determining lead and cadmium at trace levels was examined with differential pulse stripping voltammetry in the measurement step. The electrochemical response was characterized with respect to supporting electrolyte, pH of solution, accumulation time, accumulation potential, layers of LB film, and possible interferences. Calibration plots were found to be linear in the range of 2×10-7 mol/L to 5×10-5 mol/L(Cd2+) and 1×10-7 mol/L to 2.5×10-5 mol/L(Pb2+); the detection limits were 2×10-8 mol/L(Cd2+) and 8×10-9 mol/L(Pb2+). Possible recognition mechanism was also discussed.4. 2-amino-1, 3, 4-thiadiazole was synthesized by reaction of aminothiourea with oxalic acid in the presence of hydrochloric acid as catalyst in one step. The purity of the product is higher than 99% (HPLC). Its structure was characterized by IR, 13C NMR and MS. It is testified that the facile synthetic scheme put forward in this work has the characteristics of mild reaction condition, high yield, simple operation and being environmentally-friendly. At the same time, the synthesis and characterization of a Zn2+ complex with 5-ethyl-2-amino-1,3,4-thiadiazole (eatz) are described. The crystal structure of [Zn(eatz)2(OAc)2] was determined by X-ray diffraction. The crystal belongs to the monoclinic system and the structural unit is a distorted tetrahedron. In this complex, eatz acts as a monodentate ligand coordinating through the thtadiazole N atom to Zn2+, and the crystal structure is mainly stabilized by both intra- and intermolecular hydrogen bonds. |
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