Pyridine-2-sulfonic acid metal complexes

The effect of the polymer backbone on the intrinsic chemical reactivity of metal complexes has been studied in aqueous solution and in Nafion (perfluorocarbon sulfonic acid) film 44). Using a model catalyst-substrate system, the independent kinetic effects of reaction site homogeneity, substrate diffusion into the polymer film, and changes on activation parameters have been addressed. The ligand substitution reaction (6), was chosen for this purpose (Py = pyridine and its derivatives). 

First, 1 2 metal complexes of (mainly mono-) azo dyes, without sulfonic or carboxylic acid groups, and trivalent metals (see Section 3.11). The metals are preferably chromium and cobalt nickel, manganese, iron, or aluminum are of lesser importance. Diazo components are mainly chloro- and nitroaminophenols or amino-phenol sulfonamides coupling components are (3-naphthol, resorcinol, and 1-phe-nyl-3-methyl-5-pyrazolone. Formation of a complex from an azo dye and a metal salt generally takes place in the presence of organic solvents, such as alcohols, pyridine, or formamide. An example is C.I. Solvent Red 8, 12715 [33270-70-1] (1). 

As a first approximation, the reactions of pyridines with electrophiles can be compared with those of trimethylamine and benzene. Thus, pyridine reacts easily at the nitrogen atom with reagents such as proton acids, Lewis acids, metal ions, and reactive halides to form salts, coordination compounds, complexes, and quaternary salts, respectively. Under much more vigorous conditions it reacts at ring carbons to form C-substitution products in nitration, sulfonation, and halogenation reactions. 

Xerogel silica was prepared from tetraethoxysilane in the presence of different porphyrins and a template (e.g. pyridine) in an alcohol/water mixture at between 25 and 120 °C [48]. The following metal-free or Fe complexes of porphyrins were employed 2 with pentafluorophenyl, 2.6-dichlorophenyl-3-sulfonic acid, 4-carboxyphenyl or 4-methylpyridinium instead of -C6H4R. A mixture of 3 mL tetraethoxysilane and 3 mg of the porphyrin was used. It was found that the structure and morphology of the inorganic/organic hybrid materials depended on the kind of porphyrin and the xerogel preparation conditions. Side selection spectra and vibronic analysis were carried out for metal-free 2 (-CeHs, -CeFs... 

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