389070-77-3Relevant academic research and scientific papers
Metal complexes of some peptide derivatives. Part-XIV. Complex formation of copper(II) with N-benzenesulfonamides of some dipeptides
Mukherjee,Chakraborty
, p. 137 - 141 (2007/10/03)
Combined potentiometric and spectrophotometric investigation on the complex formation equilibria of CuII with N-benzenesulfonyl derivatives of some dipeptides, viz. glycylglycine, glycyl-dl-α-alanine, glycyl-dl-methionine, glycyl-β-alanine, β-alanylglycine (AH 2) in aqueous solution provides evidence of complexes of the types: Cu(AH)+, Cu(H-1AH), Cu(H-1A)-, Cu(H-1 A)(OH)2-, Cu(AH)2, Cu(H -1AH)(AH)-, Cu(H-1AH)2 2-, Cu(H-1A)(H-1AH)3- and Cu(H -1A)24-. Deprotonation constants (pK COOHH and pKSO2NHH) of the ligands and formation constants of the complexes at 25 ± 1° 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 π-interactions. Deprotonation constants of coordinated H2O molecules in the square-planar, or distorted octahedral Cu(H-1A)(H2O)- complexes indicate their equatorial disposition. The tendency of the ternary hydroxo complexes, Cu(H-1A)(OH)2- to transform into to Cu(H -1A)24- with precipitation of Cu(OH) 2 at pH >9 is found to be in the inverse order of stability constants of these complexes.
Metal complexes of some peptide derivatives. Part-XV. Mixed ligand complex formation of copper(II) with some N-benzenesulfonyldipeptides as primary ligands and acetate, 2-methylbenzimidazole, glycinate and bipyridine as secondary ligands
Mukherjee,Chakraborty
, p. 565 - 571 (2007/10/03)
Potentiometric investigation on the complex formation equilibria of CuII with N-benzenesulfonyl derivatives of some dipeptides, viz. glycylglycine, glycyl-β-alanine and β-alanylglycine, hereafter, abbreviated as NBSGG, NBSGB and NBSBG (AH2) respectively, in the presence of typical secondary ligands, viz. acetate (ac-), 2-methylbenzimidazone (bz), glycinate (gly-) and bipyridine (bipy), hereafter, B, provides evidence of formation of varieties of binary and ternary complexes of the types : Cu(AH), Cu(H-1AH), Cu(H-1A), Cu(H-1A)(OH), Cu(B), Cu(B)(AH), Cu(B)(H-1AH) and Cu(B)(H-1A). Stability constants of the complexes at 25 ± 1°, in aqueous solution at a constant ionic strength, I = 0.1 M (NaNO3) have been determined and the complex formation equilibria elucidated on the basis of speciation curves. The sulfonamidodipeptide ligands (AH2) provide three coordinating groups : -COOH, -CONH-, and -SO2NH-, and show ambidentism in forming the binary and the ternary complexes depending upon the denticity, σ-basicity and π-acidity of the B-ligands. The ternary complexes are found to be stable in the intermediate pH range (5-8). Above pH 8, the mixed ligand complexes derived from all the AH2 and B-ligands decompose to produce either the fully deprotonated binary complexes, Cu(H-1A)- or the ternary hydroxo complexes Cu(H-1A)(OH)-2 depending upon the nature of the B-ligands.
Metal Complexes of Some Peptide Derivatives: Part IV - Complex Formation of Copper(II) with N-benzenesulphonylglycylglycine
Mukherjee, G. N.,Chakraborty, P. K.
, p. 841 - 848 (2007/10/02)
Potentiometric and spectrophotometric studies of the complexation reaction of copper(II) with N-benzenesulphonylglycylglycine (NBSGG or LH2) in aqueous solution provide evidence for the formation of a variety of complexes: Cu(LH)(H2O)2(+); Cu(H-1LH)(H2O); Cu(H-1L)(H2O)(-); Cu(H-1L)(OH)(2-); Cu(LH)2(H2O)2; Cu(H-1LH)(LH)(H2O)(-); Cu(H-1LH)2(2-); Cu(H-1L)(H-1LH)(3-); and Cu(H-1L)2(4-).Formation constants of all these complexes have been determined at 25 deg C, 35 deg C and 45 deg C and μ = 0.2 mol dm-3 (NaNO3) and the accompanying changes in free energy, enthalpy and entropy have been correlated with the modes of bonding of the ligand.At pH -1LH)2(2-) in 1:5 and 1:10 systems and the terdentate (N,N,O) complex Cu(H-1L)*(H2O)(-) in 1:1 system.Metal-promoted amide deprotonation always precedes deprotonation of coordinated sulphonamido group.The (SO2NH)CuH-pK(CONH)CuH> values are found to be 0.60+/-0.05 for Cu(LH)(H2O)2(+) and 3.6+/-0.1 for Cu(LH)2(H2O)2.The (SO2NH)H-pK(SO2NH)CuH> values are 0.90+/-0.05 between LH(-) and Cu(H-1LH)2(2-) and as high as 3.8+/-0.1 between LH(-) and Cu(H-1LH)(H2O).Deprotonation constant of coordinated water in the complex Cu(H-1L)(H2O)(-) is fairly close to the values for the equatorially coordinated water in square planar complexes of Cu(II).
