Loading...

The advantage of spectrophotometric measurement for size-selective complexing of Cu(II) with O2N2-azacrown ligands

Ghanbari, B ; Sharif University of Technology | 2015

882 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/j.saa.2014.12.034
  3. Publisher: Elsevier , 2015
  4. Abstract:
  5. A comparative investigation of the interaction of Cu(II) with a series of 15- to 19-membered mixed-donor dibenzo-substituted macrocyclic ligands, each incorporating an O2N2-donor set, has been carried out using UV-Visible studies in methanol. Although a ring size effect has been reported for a related series of Ni(II) complexes, no such metal ion discrimination has been reported for Cu(II) in terms of its binding constants with 14- to 17-membered macrocycles. Employing Job's method of continuous variation established 1:1 stoichiometry for the interaction between Cu(II) and 1-5. From UV-Visible studies applying the Benesi-Hildebrand equation, the binding constants (K) of Cu(II) with 1-5 were determined to be Cu(II)/1 = 3330 (±321) dm3 mol-1, Cu(II)/2 = 33,700 (±71) dm3 mol-1, Cu(II)/3 = 7260 (±151) dm3 mol-1, Cu(II)/4 = 57,000 (±257) dm3 mol-1 and Cu(II)/5 = 13,900 (±398) dm3 mol-1 in methanol at 25 °C, respectively. The calculated binding constants showed a saw-tooth pattern in which 4 (18-membered ring) gives the highest K value for these complexes. The thermodynamic parameters (ΔG, ΔH, and TΔS) of the respective complexes have also been determined
  6. Keywords:
  7. Ligands ; Metal ions ; Methanol ; Azacrowns ; Benesi-Hildebrand ; Benesi-Hildebrand equation ; Binding constant ; Macro-cyclic ligands ; Size-selective ; Spectrophotometric measurements ; Thermodynamic parameter ; Copper compounds ; copper ; Heterocyclic compound ; Chemistry ; Kinetics ; Procedures ; ultraviolet spectrophotometry ; Aza Compounds ; Ligands ; Nitrogen ; Oxygen ; Spectrophotometry ; Spectrophotometry, Ultraviolet ; Thermodynamics
  8. Source: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 139 , March , 2015 , Pages 286-289 ; 13861425 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S1386142514018058