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Spectrophotometric studies of the reaction between 3-(2-hydroxy-4 and 5-substituted-1-phenylazo)-1,2,4-triazoles andmanganese(II) and its applications formicrodetermination ofmanganese(II) in real samples

Abdalla M.Khedr*, Mohamed Gaber

Manganese(II) reactswith 3-(2-hydroxy-4 and 5-substituted-1-phenylazo)- 1,2,4-triazoles to produce a purple violet chelates in aqueous media containing 40%(v/v)methanol. The article included an extensive study of the optimumconditions that are essential for the spectrophotometric determination of trace amounts of manganese(II) based on its chelates formation with the azodyes under interest. The molecular structures of the formed complexes were found to be 1:1 and 1:2 (Mn2+:HL). The colored dyemanganese complexes showed absorption maxima at 510, 535, 460, 480, 520, and 500 nm. Beer’s law is valid over manganese(II) concentrations up 27.47, 71.42, 54.94, 54.94, 54.94 and 49.44g ofMn(II) per 10ml,withmolar absorptivities of 3.98104, 1.57104, 0.20104, 0.10104, 0.10104 and 0.53104 lmol–1 cm–1 usingHL1-HL6, respectively.Anotable advantage of the investigated method is that the determination of Mn(II) is possible in the presence of many cations and anions. The method has been applied to the determination ofmanganese in pharmaceutical formulations with reliable analytical results. Some solid complexes were prepared and subjected to different spectroscopic and analytical techniques as well as thermal analysis in order to investigate the mode of interaction between the azo compounds and Mn(II) ion.