Complexation Studies of N, N′-ethylenedi-L-cysteine with Some Metal Ions

• Published in: Journal of solution chemistry 2009-12, Vol.38 (12), p.1504-1519
• Main Authors: Barros, M. Teresa, Martins, João, Pinto, Rui M., Santos, Mónica S., Soares, Helena M. V. M.
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Chelating; Chemistry; Chemistry and Materials Science; Complexation; Condensed Matter Physics; Electrical measurements; Electrodes; Exact sciences and technology; General and physical chemistry; Geochemistry; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Ligands; Oceanography; Physical Chemistry; Searching; Solutions; Stability constants
• ISSN: 0095-9782; 1572-8927
• DOI: 10.1007/s10953-009-9463-7

As part of a search for environmentally friendly metal chelating ligands, the stability constants of N, N′-ethylenedi-L-cysteine (EC) complexes with Ca(II), Cu(II), Mg(II) and Mn(II) were determined by potentiometry with a glass electrode in aqueous solutions containing 0.1 mol⋅L −1 KCl at 25 °C. Final models are proposed. For the Ca(II)–EC system, the overall stability constants are log  10 β CaHL =14.53±0.03, log  10 β CaL =4.79±0.01 and log  10 β CaL2 =8.38±0.04. For the M(II)–EC systems, where M=Cu(II) or Mg(II), the overall stability constants are log 10 β CuHL =31.19±0.02 and log  10 β CuL =27.02±0.06 for Cu(II), and are log  10 β MgHL =14.84±0.02 and log  10 β MgL =6.164±0.008 for Mg(II). For the Mn(II)–EC system, the overall stability constant is log  10 β MnL =10.12±0.01. Metal–chelate speciations simulations showed that EC is an efficient chelating agent for Cd(II), Co(II), Cu(II), Ni(II), Pb(II) and Zn(II) for pH≥7.