10.5281/zenodo.5846040
https://zenodo.org/records/5846040
oai:zenodo.org:5846040
G. N. Mukherjee
G. N. Mukherjee
P. K. Chakraborty
P. K. Chakraborty
Metal complexes of some peptide derivatives. Part-XIV. Complex formation of copper(II) with N-benzenesulfonamides of some dipeptides
Zenodo
2002
Combined potentiometric
spectrophotometric
equatorial disposition
2002-02-28
eng
10.5281/zenodo.5846039
Creative Commons Attribution 4.0 International
Department of Chemistry, University of Calcutta, University College of Science,
92 Acharya Prafulla Chandra Road, Kolkata-700 009, India
E-mail: gurunath@cucc.ernet.in Fax: 91-033-3519755/2413222
Bengal Chemical and Pharmaceutical Works, Kolkata-700 009, India
Manuscript received 11 August 2000, revised 13 July 2001, accepted 14 July 2001
Combined potentiometric and spectrophotometric investigation on the complex formation equilibria of Cull with N-benzenesulfonyl derivatives of some dipeptides, viz. glycylglycine, glycyl-dl-α-alanine, glycyl-dl-methionine, glycyl-β-alanine, β-alanylglycine (AH2) in aqueous solution provides evidence of complexes of the types : Cu(AH)+, Cu(H-1AH), Cu(H-1 Ai, Cu(H-1 A)(OH)2- , Cu(AH)2, Cu(H_1AH)(AH)-, Cu(H-1 AH)\(_2^2\)-, Cu(H-1A)(H-1AH)3 and Cu(H_1A)\(_2^4\)- .Deprotonation constants (pKHCOOH and pKHSO2NH) of the ligands and formation constants of the complexes at 25 ± 10 in aqueous solution, I = 0.2 M (NaNO3), are correlated with the modes of coordination of the amide and sulfonamide groups, size of the chelate rings, and metal-ligand and ligand-ligand it-interactions. Deprotonation constants of coordinated H2O molecules in the square-planar, or distorted octahedral Cu(H-1A)(H20)- complexes indicate their equatorial disposition. The tendency of the ternary hydroxo complexes, Cu(H_1A)(OH)2- to transform into to Cu(H_1A)\(_2^4\)- with precipitation of Cu(OH)2 at pH >9 is found to be in the inverse order of stability constants of these complexes.