Nuclear Magnetic Resonance as a Tool for Determining Protonation Constants of Natural Polyprotic Bases in Solution

Design, synthesis and binding properties of conformer-independent linear ADA hydrogen-bonding arrays

“…We therefore determined dimerization constants and association constants for appropriate pairings of compounds 1, 2, 3b, 4 and 5 ( Table 1). Figure 3 illustrates representative curve fitting performed using the HypNMR program 26 and a representative example of the 1 H NMR spectrum of 3b on titration with 5; as expected, complexation induced shifts are observed, the most prominent of which is H e . Binding of 3b to 5 was found to occur with a modest association constant of K a = 56 M -1 (accounting for self-dimerisation of both components).…”

Lactonization and Protonation of Gluconic Acid: A Thermodynamic and Kinetic Study by Potentiometry, NMR and ESI-MS

“…The fitting result of gluconate chemical shifts versus pC H by the program HypNMR2000 (21) is depicted in Figure 2, and the calculated protonation constants are summarized in Table II. As pC H changes from 2.0 to 6.0, the largest displacement of chemical shift occurs to the C1 (C=O) atom (Figure 2), which suggests that the carboxylic group is deprotonated.…”

Structural-topological preferences and protonation sequence of aliphatic polyamines: a theoretical case study of tetramine trien

“…For instance, considering well-studied tetramine spermine, 30% (HL p ) and 70% (HL s ) was reported by Borkovec at al [8] whereas essentially equal molar ratio for both tautomers was found by Albelda et al [41], both results came from CEA. This is not entirely surprising when one recalls that the cluster expansion analysis (i) involves a lot of unknowns to be fitted into experimental data (e.g., there are 16 parameters in the case of tetramine spermine [42]) and (ii) the protonation microconstant of each protonation site must be determined from the NMR studies (often experimental NMR protonation constants differ significantly from those determined by most accurate technique, glass electrode potentiometry [43]) and, hence this unavoidably carries some degree of mathematical/statistical and experimental uncertainty.…”