التقدير الطيفي لايونات العناصر الفلزية (الكوبلت Co(II) والنيكل Ni(II) والنحاس Cu(II) ) باستخدام كاشف ازو شف جديد (DMIPNI)

Spectrophotometric determination of Co(II), Ni(II) and Cu(II) metal ions Using a New Azo - Schiff Reagent (DMIPNI)

Abstract

This study involves synthesis and identification of a new azo reagent , The reagent was synthesized by reacting of P-aminoacetophenone with P-nitroaniline in the first step by diazotization reaction , then reacting with 4,5-diphenylimidazole as a second step to give the reagent 1-(4-(((4,5-dimethyl-1H-imidazol-2-yl)diazenyl)methyl) phenyl) -N-(4-nitrobenzyl)ethan-1-imine(DMIPNI) . The reagent was characterized by using FT-IR spectroscopy and 1H-NMR spectroscopy . Metal complexes with Co(II),Ni(II),Cu(II) were prepared. The ligand and their complexes were characterized by FT-IR spectroscopy and 1H-NMR spectroscopy.The physical data were investigated such as molar electrical conductivity, melting point and magnetic sensitivity. The optimal conditions for the formation of these complexes were studied such as acidic function, reagent concentration , time the stability of the formed complexes , effect the temperature on stability of the complexes , the order in which the concentrations of reaction components are added and that obey Beer- Lambert’s law were determination by calibration curve within the range (0.05-1.00) μg / mL for Cobalt(II) complex and (0.01 – 1.00 ) μg / mL for Nickel(II) and Copper(II) complexes . The sandell sensitivity, molar absorption coefficient and correlation coefficient were determined and they were as follows( 3.7×10-4 μg / cm2, 2.96×10-5μg /cm2 , 7.41×10-5μg /cm2), ( 0.16×106L.mol-1.cm-1, 0.198×107 L.mol-1.cm-1, 0.857×106 L.mol-1.cm-1) , (0.9996,0.9998,0.9995) for Cobalt(II), Nickel(II) and Copper(II) complexes respectively. The equivalence of the constituent complexes was studied by finding the ratio of metallic ion to reagent (M:L) using molar ratio method and continuous variation method , the results indicate that the ratio was (1:2) (metal: reagent) for all complexes. The stability constants were calculated to be ( 12.1359×1010 L / moL) ,( 3.4515×1010 L / moL) and (15.0866×1010 L / moL) for Cobalt(II),Nickel(II) and Copper(II) complexes respectively. In addition to that , thermodynamic function ∆G°,∆H° and ∆S° were calculated for the synthesis complexes at different temperature (288,298,308,318,328,338)K , it was found that the stability constants of complexes decreases with increasing temperatures because it is exothermic reactions and that the reactions of formation of all complexes occur spontaneously. The charge of the dissolved complexes was determined using the electrical conductivity and magnetic sensitivity and the results showed that all of complexes are uncharged, and from it we conclude that the complexes formed are octahedral. Also, the precision, accuracy and sensitivity of the spectral analytical method used were determined using standard solutions of selected ions with standard solutions of reagent from which the standard deviation , relative standard deviation and the relative percentage error whose limits were not exceeding (±5) and percentage recovery for three different concentrations it was concluded that the spectral method used is of good accuracy, precision and sensitivity