Complexation Behavior of Cu²⁺ in the Presence of Iminodiacetic Acid and Poly(ethyleneimine)

Abstract

Summary: Multicomponent aqueous systems containing Cu2+ as metal ion, iminodiacetic acid (IDAA) as a low‐molecular‐weight chelating molecule, and branched poly(ethyleneimine) (BPEI) as a polychelatogen are analyzed at different pH by UV‐Vis spectroscopy and diafiltration. It was found that at pH 4, saturation of BPEI with Cu2+ takes place at a Cu2+:BPEI ratio of 1:5.7, probably indicating a stoichiometry for the complex of 1:4. At the same conditions the Cu2+‐IDAA complex has a stoichiometry of 1:1. The ability of BPEI to bind the metal ion is higher than that of IDAA in mixtures of both chelating molecules. Lowering the pH between 2 and 3.5, protonation of BPEI allows increasing the amounts of Cu2+‐IDAA complex so that Cu2+ is transferred from the polychelatogen to IDAA. Good correlations are found comparing the results obtained by diafiltration and by UV‐Vis spectroscopy. Moreover, diafiltration results indicate that in the absence of Cu2+, IDAA interacts with BPEI with apparent dissociation constants of 2.88 at pH 2.7 and 0.96 at pH 4. These interactions may be responsible for the appearance of an apparent dissociation constant of 3.60 for the interactions between BPEI and the Cu2+‐IDAA complex at pH 4.

Cu2+-Loaded Polydopamine Nanoparticles for Magnetic Resonance Imaging-Guided pH- and Near-Infrared-Light-Stimulated Thermochemotherapy

“…By fixing the concentration of DA, the as-prepared CuPDA NPs exhibit the highest absorbance at 808 nm with a DA-to-Cu 2+ feed ratio of 1:1.25. According to our previous study, the increased absorption in the UV–vis–NIR region is attributed to formation of Cu 2+ complexes . For CuPDA NPs, the Cu 2+ interacts with PDA through coordinative interaction, because PDA possesses a large number of amino, hydroxyl, and carboxyl groups .…”

“…According to our previous study, the increased absorption in the UV−vis−NIR region is attributed to formation of Cu 2+ complexes. 38 For CuPDA NPs, the Cu 2+ interacts with PDA through coordinative interaction, because PDA possesses a large number of amino, hydroxyl, and carboxyl groups. 39 At lower Cu 2+ ratio, the tetracoordinated structure is dominant, which leads to stronger NIR absorption than other the less coordinated structure.…”

Role of Halide Ions for Controlling Morphology of Copper Nanocrystals in Aqueous Solution

“…CuCl 2 and CuBr 2 were reduced rapidly to CuCl and CuBr, respectively, because of the weak reducibility of ascorbic acid and the low solubility of CuCl and CuBr, and they were precipitated quickly. In the present reaction, however, BPEI first makes a BPEI−Cu ion complex due to the strong binding capacity of the amine functional group in BPEI, thereby preventing the formation of CuCl and CuBr during the reaction ( Figure S2 d in supporting information) . In addition, Cu particles with a larger size were observed when a large amount of BEPI was used ( Figure S3 , a and b in supporting information).…”

Mercury and lead sorption properties of poly(ethyleneimine) coated onto silica gel

“…Poly(ethyleneimine) is well known for its metal chelation potentialities [6][7][8][9][10][11]. On the other hand, silica gel offers good enough stability to solvents and pressure to be used in column systems, wide scales of porous volume, specific area, available sizes, and availability for immobilizing organic molecules [12].…”