Potentiometric ion‐pair titrations of metal ions forming complexes with 1,10‐phenanthroline and its derivatives

Abstract

Simple coated-wire electrodes. prepared using an ordinan aluminum wire conductor covered with the plasticized poly(viny1 chloride) membrane. were used in potentiometric titrations of metal ions forming complexes with 1.10-phenanthroline and its derivatives. The method is based on the precipitation of ion pairs formed by metal phenanthroline complexes and tetraphenylborate. Titrations were accompanied with titration cun-es yielding v e n sharp potential breaks, so that ver). reproducible results could be taken even in titrations. of quite diluted solutions (down to 2.5 x 10-mol of the metal ion in the 25 cm3 of the sample titrated). Using the procedure described, the following cations were titratable in forms of their 1,lO-phenanthroline complexes: Zn". CdLi. Mn'-. Fez-, Fe'-, CoL-, Ni", Cu", VO"' , Ga3-. In'-. and TI'-. Some of the metal ion solutions, prepared from the salts of anal!.tical-reagent-gmde purin, can be recommended for use in standardization procedures of the sodium tetraphenylborate titrant. 2,9-Dimethyl-l ,lo-phenanthroline complexes of ZnL+, Cd'+. and Cu+ were also titrable. but the results were significantly erroneous. Metal 4,7-diphenyl-l,l 0-phenanthroline complexes were insoluble in water as well as in water/ethanol mixtures.

Development and characterization of a novel electrochemiluminescent reaction involving cadmium

“…Polarographic studies indicate the existence of aqueous Cd 2+ complexes having the formula Cd(phen) 3 2+ in the presence of 100-fold excess phenanthroline. 18 Using the reported stability constants for the mono-, bis-, and tris-complexes, 19 the analyte solution was computer modeled using Matlab 5.3 (The Mathworks Inc., Natick, MA, USA) on a Silicon Graphics Indigo 2 workstation and this proved that the tris-phenanthroline complex is the most prevalent. The concentration curves produced show an increase in the tris product as the ratio of Cd 2+ to phenanthroline decreases, with a corresponding drop in the concentrations of the mono-and bis-species.…”

“…The competitive process occurring between Cd 2+ , Co 2+ , Ni 2+ and Zn 2+ can be explained by the binding constants (log ß 3 ) of these ions with phenanthroline, 14.92, 19.90, 24.8 and 17.44, respectively. 19 These constants suggest that all three of these metals should mask the presence of Cd 2+ by preferentially binding to the ligand.…”

Iron (III) Ion Sensor Based on the Seedless Grown ZnO Nanorods in 3 Dimensions Using Nickel Foam Substrate

“…The potentiometric sensor was also used in the titration of iron phenanthroline complex against sodium tetraphenylborate solution based on aluminium wire conductor covered with a plasticized PVC membrane [17]. Crown ethers of 18C6 were also employed for the development of lanthanum [18] and sodium [19] selective electrodes due to their ease in complex formation with metal ions.…”

Utilização de um eletrodo de grafite-epóxi recoberto com [Zn(FEN)3][tetratris(4-clorofenil) borato]2 sensível a zinco(II) em meio 1,10-fenantrolina como eletrodo indicador em titulações potenciométricas de precipitação

“…Os complexos metálicos formados com o ligante 1,10-fenantrolina foram utilizados como contra-íon na construção de eletrodos de membrana líquida para determinação de ânions 27 . Vitras e Varmuzova 28 desenvolveram eletrodos íon-seletivos de membrana de PVC, usando 1,10-fenantrolina como complexante para diversos cátions metálicos na formação do par-iônico com tetrafenilborato. Entretanto, esses sensores mostraram baixa seletividade para diversos cátions metálicos que formam complexos parcialmente solúveis com a 1,10-fenantrolina e tempo de vida útil limitado, devido à degradação do par-iônico.…”