Abstract
Three cationic porphyries, 5, 10, 15, 20-tetrakis(1-methyl-2-pyridinio)porphine [T(2-MPy)P], 5, 10, 15, 20-tetrakis(1-methyl-3-pyridinio)porphine [T(3-MPy)P] and 5 10, 15, 20-tetrakis(1-methyl-4-pyridinio)porphine [T(4-MPy)P], react rapidly and quantitatively with silver(I) to form yellow complexes in alkaline solutions of pH 9.6-12.0, which are oxidized to the corresponding red silver(II) complexes by dissolved oxygen at room temperature. The silver(II) complexes formed were stable and remained unchanged for at east 2h. The composition of the silver(II) complex was determined to be 1:1 (metal:ligand) by both the continuous variation method and the molar ratio method. Highly sensitive spectrophotometric methods for the determination of the trace amounts of silver have been developed. The apparent molar absorptivities of the silver(II) complexes of T(2-MPy)P, T(3- MPy)P and T(4-MPy)P were 3.00×105, 3.36×105 and 2.30×105lmol-1 cm-1, respectively. Cadmium(II), coba t(II), copper(II), mercury(II), manganese(II), zinc(II), halogenides, thiocyanide and cyanide interfered with the silver determination.
