| Oscillatory chemical system, which is maintained far-from equilibrium by keeping it open, has complicated dynamics properties, such as orderly structure of time and space, self-organization and so on. At this stage, researches about chemical oscillating system has focused on two aspects:one is searching the new oscillator and probing the mechanism, another is about the application of oscillating chemical system and its computer simulation. Among all oscillating systems, both Belousov-Zhabotinskii type of reaction (with Ce4+, Mn2+, Fe(phen)32+, or Ru(bipy)32+as catalysts) and Briggs-Rauscher type of reaction involving metal ion catalysts (Ce4+, Mn2+) have been extensively studied.This paper reports a new BR oscillator and its mechanisms. We also report the application of BR oscillators on detecting two phenols (eugenol and thymol). The new BR oscillator contains tetraaza-macrocyclic nickel complex as catalyst and tricarboxylate oxaloacetate as substrate. This chemical oscillator is designed for simulation of biological oscillation. Two other BR oscillators are used for quantitative analysis of phenols.First, we introduced the conception and development process of nonlinear chemistry, and discussed the catalyst of oscillator, highlighting macrocyclic metal complexes as catalysts for oscillating system.Second, the catalyst tetraaza-macrocyclic metal complexes-[NiL](ClO4)2was synthesized according to the literature. The ligand L in the complex is5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene. Then, the new oscillator KIO3-HOCOCOCH2COOH-[NiL](ClO4)2-H2SO4-H2O2was studied. This organic substrate is the intermediates of tricarboxylic acid cycle, and acid environment pH value close to pH in living organisms, making such a new oscillation system for simulation of biological systems. We also have searched the ranges of initial concentration and explored the effects of temperature and additives on the oscillatory behavior of the system. Then the the possible reaction mechanism using the FCA model has been proposed.Third, Determination of phenols by using BR oscillating systems.a) Determination of phenols by using [NiL](ClO4)2catalyzed BR oscillator.We demonstrated here that, for the first time, a macrocyclic Ni(II) complex-catalyzed BR oscillating reaction is appropriate matrix in quantitative measurement of lipophilic antioxidant eugenol. Addition of eugenol on such BR oscillating system results in quenching and subsequently regenerating oscillations. The inhibition time obtained shows sectional dependence on the antioxidant eugenol concentration over the range of5×10-7M～2.5×10-5M. An assay of eugenol was thus established. Although the cyclic voltammograms shows that eugenol has the ability to directly react with KIO3(or [NiL]2+), it is more reasonable to believe that eugenol responses to HOO(?) radical. Using the same experimental method for determining thymol, get the analysis of the measuring range of1×10-5M～3×10-4M.b) Determination of phenols by using Mn2+catalyzed BR oscillator.Use the above method to discuss the effect of Eugenol on classic Mn2+catalyzed BR system. Experimental results have shown that addition of eugenol into these BR systems could quench and then successively regenerate the oscillations, accompanying by an inhibitory time that relies on the concentration of the eugenol added. But the [NiL](ClO4)2catalyzed BR oscillator is more suitable for detect eugenol for lower limits of detection. The results also have shown that the mechanism about these two oscillator were different. Eugenol can inhibite not only Mn2+catalyzed BR oscillator but can also promote it after inhibition. |
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