Chelating properties of EDTA-type ligands containing six-membered backbone ring toward copper ion: Structure, EPR and TD-DFT evaluation

Abstract

The P-APC ligands (EDTA-like aminopolycarboxylate ligands comprising 1,3-propanediamine backbone) H 4 pdta, H 4 pd3ap, H 4 pddadp and H 4 pdtp (H 4 pdta = 1,3-propanediamine-N,N,N 0 ,N 0 -tetraacetatic acid; H 4 pd3ap = 1,3-propanediamine-N,N,N 0 -triacetic-N 0 -3-propionic acid; H 4 pddadp = 1,3-propanediamine-N,N 0 -diacetatic-N,N 0 -di-3-propionic acid; H 4 pdtp = 1,3-propanediaminetetra-3-propionic acid) were investigated. The chelating ligands coordinate to copper(II) via five or six donor atoms affording distorted trigonal-bipyramid and octahedral structures that were verified by X-ray analysis for Ba[Cu(pd3ap)]Á 6H 2 O (1) and trans(O 6 )-Ba[Cu(pddadp)]Á8H 2 O (2) complexes respectively. The impact of counter-ions on the P-APC complexes is shown in detail together with the analysis of another strain parameters. EPR spectral results confirm the penta-coordination of 1 and hexa-coordination of 2 in aqueous solution, even if several Cu(II) species with different protonation degree exist as a function of pH, and indicate that a hexa-coordinated structure is favored when the two axial COO À donors close five-membered chelate rings. We also present here the results of molecular mechanics (LFMM) calculations based on our previously-developed force field along with results of DFT (Density Functional Theory). On the basis of extensive DFT and TD-DFT calculations the B1LYP/6-311++G(d,p) level has been seen as an accurate theory for calculating and predicting the UV-Vis spectra in case of copper-P-APC compounds.

Synthesis of nanosized MFI zeolites using Cu-containing complexes

“…S4. The coordination compound itself is sufficiently flexible, as shown earlier, [34] and this allows to fit in the available channel intersection. The calculated binding energy with respect to isolated Na 2 [Cu-EDTA] coordination compound and empty zeolite model is large (-317 kJ/mol).…”

Mediating Anion-Cation Interactions to Improve Aqueous Flow Battery Electrolytes

“…The vibration at 1626 cm −1 which is assigned to antisymmetrical carboxyl stretching of CrPDTA, [45][46][47][48] is redshifted by 11 cm −1 with increasing urea concentration, strongly indicating that CrPDTA H-bonds with urea (Figure 3c). Similar carboxyl-urea interactions have previously been studied in the area of supramolecular chemistry and have been exploited for neutral anion receptors.…”

“…A smaller 13 C NMR upshift with KCrPDTA is observed and KCrPDTA concentration dependent IR redshifts of ca. 2 cm −1 for the vibration at 1361 cm −1 , assigned to symmetrical carboxyl stretching modes of the CrPDTA anion, [45][46][47][48] indicate weaker CO bonds, i.e., interaction of anion carboxyl groups with a positive charge (Figure S4c). For the same vibration, a urea concentration dependent redshift of comparable 2 cm −1 is observed at a constant salt concentration of 500 mм KCrPDTA (Figure S4d).…”

Copper Sorption and Transport in an Acidic Brown Soil

“…Numerous studies have demonstrated that Cu mobility is mainly controlled by sorption to soil organic matter (SOM), where carboxylic and hydroxylic (or amine) groups form very stable five-to sixmembered ring chelates with Cu 2+ [11,18,21,27,35]. Cu can also adsorb to Fe-, Mn-or Al-(hydro)oxides, and clay minerals, forming inner-sphere complexes and/or surface precipitates [7,8,14,46].…”