ISSN 2321-807X Volume 14 Number1 Journal of Advances in chemistry 6021 | Page September 2017 https://cirworld.com/ Electrochemical andspectrastudies of some sulfa drug azodyes and their metal complexes in aqueous solution E.M. Mabrouk 1 , Kh.A.Al—Omary 2 ,A.S.Al-Omary 2 and E.H. El-Mossalamy 1 1 Chemistry Department, Faculty of Science, Benha University, Benha,13518, Egypt. 2 Chemistry Department, Faculty of Applied Science, Umm Al-Qura University, Makkah Al-Mukarrama, Saudi Arabia. Email of corresponding authors: emmabrouk90@yahoo.com, sbdmina@yahoo.com Abstract The electrochemical behavior of some azo compounds derived from sulfa drugs derivatives in B.R. buffer solutions of different pH containing 20 (v/v) ethanol was investigated at the mercury electrode using different techniques (DC,DPP,CV and Coulometry) to investigate the effect of medium on the electro reduction process and suggestion the electrode reaction mechanism. The obtained results denoted that these compounds were reduced undergo a single irreversible 4- electron polarographic wave in acid and neutral solutions which represent the cleavage of the N=N center to the amine stage, whereas in alkaline solution, two wave are obtained the second is 2-electron irreversible wave corresponding to the reduction ofCHO group to CH2OH. The DPP and CV data showed a single peak in solutions of pH< 8, whereas three peaks are in alkaline solutions. The dissociation constants of the investigated compounds were determined by using spectrophotometric and potentiometric methods. Also the metal – ligand formation constants were determined potentiometrically and found in the order Cu˃ Co˃ Ni ˃Zn. Keywords; Sulfa drug azo; Polarography; Cyclic voltammetry; Potentiometry; Spectrophotometry 1.1. Introduction Sulfa drugs and their derivatives as well as their metal complexes are considered to be very important compounds due to their uses and applications in several and biological purposes. They are extensively used for the treatment of diseases caused by several microorganisms [1]. Also, sulfa drugs containing azo group are of great importance due to their useful as models for biological systems, i.e, antifungal, antibacterial,anticancer and antimalarial [2,3]. On the other hand, azo compounds occupy a good position as analytical reagents [4, 5], their applications aschromophoric and metallochromophoric reagents [6-8], photo-sensitizers [9, 10] and sensors [11-13]. Therefore, the electrochemistry of these compounds was the subject of many electro-chemists. Although polarographic and voltammetric studies of azo compounds are frequently carried out [15-27], little attention was paid to investigate the electrochemical behavior those derived from sulfa drugs. Recently, several studies were carried on the electrochemistry of azo compounds using different techniques[28-30]. The present study aims to investigate the electro-reduction of some sulfa drugs azo compounds at the mercury electrode to elucidate their electrode reaction pathway using several techniques as well as determination of their dissociation constants using spectral and potentiometric methods. The study was extended to calculate the stability constants of complexes of these compounds with some transition metal ions in solution. 2. Experimental 2.1. Preparation of the solid azo compounds All chemicals used in the present investigation were of analytical grade and used without further purification. The solidazo compounds (I-IV) were prepared [31] by gradual addition of an aqueous cold solution of sodium nitrite (0.01 mole) to a concentrated hydrochloride acid solution of sulfamethazine, sulfamerazine and sulfadiazine (0.01) mole with continuous stirring and kept for about 20 min in ice bath.The formed diazonium salt solutions were added gradually with vigorous stirring to cold solutions of salicylaldehyde or phenol(0.01 mole) dissolved in 0.01M NaOH. After dilution, the obtained solid compounds were filtered off and washed with water. The crude materials were recrystallized from ethanol. These azo compounds were characterized by IR and 1 H-NMR spectra. R1=R2=CH3 R3=CHO (I); R1=CH3 R2=H R3=CHO (II); R1=R2=H R3=CHO (III); R1=R2=CH3 R3=H (IV)