title: Potentiometric and thermodynamic studies of 5-(p-aminophenylazo)-8-hydroxyquinoline and its metal complexes.
abstract: Proton-ligand dissociation constant of 5-(p-aminophenylazo)-8-hydroxyquinoline (HL) and metal-ligand stability constants of their complexes with bivalent (Mn2+, Co2+, Ni2+ and Cu2+) metal ions have been determined potentiometrically in 0.1 M KCl and 30% (v/v) dimethyl formamide (DMF)-water mixture. The order of the stability constants of the formed complexes was found to be Mn2+ < Co2+ < Ni2+ < Cu2+. The effect of temperature was studied and the corresponding thermodynamic parameters (delta G, delta H and delta S) were derived and discussed. The dissociation process is nonspontaneous, endothermic and entropically unfavorable. The formation of the metal complexes has been found to be spontaneous, endothermic and entropically favorable.
authors.affiliation: Basic Engineering Science Department, Faculty of Engineering, Menoufiya University, Egypt.
authors.forename: M F
authors.initials: MF
authors.lastname: el-Sherbiny
authors.forename: A A
authors.initials: AA
authors.lastname: al-Sarawy
authors.forename: A A
authors.initials: AA
authors.lastname: el-Bindary
mesh_terms: D000465:Algorithms; D001391:Azo Compounds / Q000737:chemistry*; D006912:Hydroxyquinolines / Q000737:chemistry*; D007202:Indicators and Reagents; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D011199:Potentiometry; D011522:Protons; D013696:Temperature; D013816:Thermodynamics
chemical_list: C468907:5-(p-aminophenylazo)-8-hydroxyquinoline; D001391:Azo Compounds; D006912:Hydroxyquinolines; D007202:Indicators and Reagents; D008024:Ligands; D008670:Metals; D011522:Protons