The acid-base properties of N,N9-disubstituted dithiooxamides derived from alkyl-a-aminoacids or glycylglycine were studied in aqueous solutions of pH 2.5-10.8. For each dithiooxamide, protonation constants were obtained from potentiometric data for three dilute aqueous solutions [I50.15 M (NaClO ), 37.08C] using the program HYPERQUAD, and are reported as conventional pK values. For 4 a compoun...

The site-specific basicities of imatinib (Gleevec, a new signal transduction inhibitor drug of chronic myeloid leukemia) and two of its fragment compounds were quantitated in terms of protonation macroconstants, microconstants, and group constants by NMR-pH and pH-potentiometric titrations. Sequential protonation of imatinib follows the N(34), N(11), N(31), N(13) order, in which N(11) and N(31)...

The protonation constants of the macrocyclic ligand 1,4,7-triazacyclononane-N,N’,N”-triacetic acid (NOTA) have been measured by potentiometry, and the protonation sequence of the various amino and carboxylate groups of NOTA has been studied in DzO as a function of pD from the chemical shifts of the nonlabile protons. Shielding constants for protonation of the amino groups were determined in a N...

A new tris-(2-aminoethyl)amine (TREN) capped tripodal Schiff base ligand has been developed by mimicking structural features of a natural siderophore, Bacillibactin, by substituting the catechol units with salicylaldehyde and employing amino acid as spacer. Synthesis of the ligand N-[2-[bis[2-[[2-[(2-hydroxyphenyl)methylamino]acetyl] amino]ethyl]amino]ethyl]-2-[(2-hydroxyphenyl)methylamino]...

the dependence on ionic strength of protonation of l-aspartic acid and its complexation withdioxouranium(vi) is reported in sodium perchlorate solution as a background salt. the measurementshave been performed at 25 ± 0.1 °c and various ionic strengths in the range 0.1 to 1.0 mol dm-3, using acombination of potentiometric and spectrophotometric techniques. the overall analysis of the present an...

The dependence on ionic strength of protonation of L-aspartic acid and its complexation withdioxouranium(VI) is reported in sodium perchlorate solution as a background salt. The measurementshave been performed at 25 ± 0.1 °C and various ionic strengths in the range 0.1 to 1.0 mol dm-3, using acombination of potentiometric and spectrophotometric techniques. The overall analysis of the present an...

The synthesis of ligand L based on a 2,6-bis[(N,N-bis(methylene phosphonic acid)aminomethyl] pyridine scaffold is described. Potentiometry combined with UV-Vis absorption spectrophotometric titrations were used to determine the protonation constants of the ligand and the stability constants of its corresponding Cu(II), Ni(II), Zn(II) and Ga(III) cations (0.1 M NaClO(4), 25.0 °C). The physico-ch...

The protonation equilibria of four substituted N-methylbenzenesulfonamides, X-MBS: X = 4-MeO (3a), 4-Me (3b), 4-Cl (3c) and 4-NO(2) (3d), in aqueous sulfuric acid were studied at 25 °C by UV-vis spectroscopy. As expected, the values for the acidity constants are highly dependent on the electron-donor character of the substituent (the pK(BH+) values are -3.5 ± 0.2, -4.2 ± 0.2, -5.2 ± 0.3 and -6....