Assessing the formation of weak sodium complexes with negatively charged ligands
| Autor: | Enrico Prenesti, Pier Giuseppe Daniele, Pieremanuele Canepa, Silvia Berto, Enrico Chiavazza |
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| Rok vydání: | 2016 |
| Předmět: |
sodium complexes
020209 energy Sodium Inorganic chemistry Binding energy General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 010402 general chemistry DFT 01 natural sciences Ion Metal Ab initio quantum chemistry methods 0202 electrical engineering electronic engineering information engineering Physical and Theoretical Chemistry sodium complexes poly-carboxylic acid stability constants potentiometry DFT Ligand 0104 chemical sciences stability constants chemistry potentiometry Stability constants of complexes Ionic strength visual_art visual_art.visual_art_medium Physical chemistry poly-carboxylic acid |
| Zdroj: | Physical Chemistry Chemical Physics. 18:13118-13125 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/c6cp00192k |
| Popis: | The stability of sodium complexes with poly-carboxylic and polyamino-carboxylic acids is investigated with ion-selective electrode-Na(+) potentiometry, working at strictly constant ionic strength. It is observed that the formation constants of the Na(+) complexes with monoligand stoichiometry (ML) increase with the number of charges on the ligand. For example, in poly-carboxylic acids this dependency is linear and is well captured by an experimental equation. A different behaviour is observed for the poly-amino carboxylic acids, which show higher complexation capabilities reaching a plateau of the binding energy past a specific ligand size. The experimental results are discussed qualitatively using ab initio calculations based on DFT B3LYP, and the principal electronic characteristics of the ligands under investigation are identified. As a result of the flexibility imparted by the long chains of polyamino-carboxylic ligands, both experimental and theoretical models demonstrate that nitrogen atoms in proximity of Na(+) ions can participate in the metal coordination, thus providing further stabilization for the complexes. Moreover, by increasing the ligand size the stabilization gained in terms of ΔG reached a plateau for EDTA, in agreement with experimental observations. |
| Databáze: | OpenAIRE |
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