Triazines solution complexes

Analysis of antioxidant activity by performing a FRAP assay was proposed by Benzie and Strain [23]. It involves colorimetric determination of the reaction mixture in which the oxidants contained in the sample reduce Fe ions to Fe. At low pH, Fe(in)-TPTZ (ferric-tripyridltria-zine) complex is reduced to the ferrous (Fe ) form and intense blue colour at 593 nm can be observed. The FRAP reagent is prepared by mixing 2.5 ml of TPTZ (2,4,6-tris (l-pyridyl)-5-triazine) solution (10 mM in 40mM HCl), 25 ml acetate buffer, pH 3.6, and 2.5 ml FeCl3 H20 (20 mM). The colour of Fe(II)(TPTZ)2 which appears in the solution is measured colorimetri-cally after incubation at 37°C. The measurement results are compared to those of a blank sample, which contains deionised water instead of the analysed sample. The duration of the assay differs from one study to another 4 min [23, 24], 10 min [25] to 15 min [26]. The analysis results are converted and expressed with reference to a standard substance, which can be ascorbic acid [26], FeS04 [23, 25], Trolox [27,18]. 

In the triazine and 9EA MIP model systems predictions may be made based on previous studies of closely related solution complexes. Of particular relevance is the work by Welhouse and Bleam [101] on solution complexes of ATR formed by hydrogen bonding with various small molecules and the work by Lancelot on the... 

The H+ and NH forms of homoionic montmorillonite promote the hydrolysis of chloro-s-triazines to the hydroxy analogs (hydroxy-s-triazines) (73). Apparently, the surface acidity of these clays was extremely high, since no degradation was observed in control experiments conducted at pH 3.5 in homogeneous aqueous solution. Russell et al. (73) suggested that the hydroxy-s-triazine products were stabilized in the protonated form at the silicate surface. The IR spectra of these surface complexes agreed with the spectra obtained in 6N HC1, and it was inferred that the pH at the clay surface was 3 to 4 units lower than that measured in suspension. 

Slow diffusion of the triazine and the silver salt solutions afforded monocrystals suitable for X-ray diffraction in the cases of complexes 124,125 and 127. Compounds 124 and 127 have structures that are practically identical and only the latter will be discussed. Figure 3.15 gives a representation of complex 125. 

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