Calix[4]Resorcinarene Macrocycles Interactions with Cd 2+ , Hg 2+ , Pb 2+ , and Cu 2+ Cations: A QCM‐I and Langmuir Ultra‐thin Monolayers Study

• Published in: Electroanalysis (New York, N.Y.) N.Y.), 2020-04, Vol.32 (4), p.755-766
• Main Authors: Eddaif, Larbi, Shaban, Abdul, Szendro, István
• Format: Article
• Language: English
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/elan.201900651

Stable ultra‐thin Langmuir monolayers of calix[4]resorcinarene derivatives, namely: C‐dec‐9‐enylcalix[4]resorcinarene‐O‐(R+)‐α‐methylbenzylamine (Ionophore I ), and C‐dec‐9‐enylcalix[4]resorcinarene‐O‐(S‐)‐α‐methylbenzylamine (Ionophore II ), were prepared at the air‐water interface. Their interactions with a series of heavy metals (HM) ions (Cu 2+ , Pb 2+ , Hg 2+ and Cd 2+ ) present in the aqueous subphase were investigated by measuring surface pressure‐area isotherms, at different concentrations. The surface pressure‐area (Π‐A) isotherms were stable and demonstrated the HM amounts influence on the limiting area (A lim ) values, therefore confirming the examined macrocycles capability to host the metallic toxicants. Additionally, a HM concentration dependence was realized and interpreted by a selective tendency of both ionophores towards Cu 2+ and Cd 2+ ions over Pb 2+ and Hg 2+ , especially at high concentrations. The HM ions interactions with the applied calix[4]resorcinarene Langmuir ultra‐thin monolayers were interpreted based on the Gibbs‐Shishkovsky adsorption equation. Moreover, quartz crystal microbalance with impedance measurement (QCM‐I), was applied for the detection of HM ions in solutions. The QCM‐I results showed the effectiveness of the coated QCM‐I crystals in detecting the ions at different concentrations. The detection limit values were in the order of 0.16, 0.3, 0.65, 1.1 ppm (Ionophore I), as well 0.11, 0.45, 0.2, 0.89 (Ionophore II) for the Cu 2+ , Pb 2+ , Hg 2+ and Cd 2+ cations, respectively. Additionally, a selective tendency of both ionophores towards copper ions was shown.