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The kinetics of the decarboxylation reactions of pentafluorobenzoic and tetrafluorobenzoic acids by various N-bases were studied using ¹⁹F NMR spectroscopy. The rate constants of these reactions are dependent on the structure of the fluorinated acid and the pKa values of the N-bases. Pentafluorobenzoic acid is decarboxylated about two orders of magnitude faster than tetrafluorobenzoic acid. With increasing pKa values of the protonated N-bases these reactions became much slower. These results suggested that the rate-determining step of the studied reactions is the attack of the conjugated acid (protonated N-base) on carboxylate anion. Copyright © 2001 John Wiley & Sons, Ltd.

The kinetics of the decarboxylation reactions of pentafluorobenzoic and tetrafluorobenzoic acids by various N‐bases were studied using 19F NMR spectroscopy. The rate constants of these reactions are dependent on the structure of the fluorinated acid and the pKavalues of the N‐bases. Pentafluorobenzoic acid is decarboxylated about two orders of magnitude faster than tetrafluorobenzoic acid. With increasing pKavalues of the protonated N‐bases these reactions became much slower. These results suggested that the rate‐determining step of the studied reactions is the attack of the conjugated acid (protonated N‐base) on carboxylate anion. Copyright © 2001 John Wiley & Sons, Ltd.

5,5′-dibromo-3-diethylaminomethyl-2,2′-biphenol N-oxide was studied by IR and NMR spectroscopy in chloroform and acetonitrile solutions. Two intramolecular hydrogen bonds are present in these molecules. The NO⋯H+⋯O−bond formed between the OH and the N-oxide groups is very strong. The proton potential is flat and broad and has probably no barrier. This hydrogen bond shows only slight proton polarizability. The other hydrogen bond formed between two hydroxyl groups OH⋯O−⇌−O⋯HO is weaker and show large proton polarizability. The proton motions in both hydrogen bonds are not coupled and therefore these hydrogen bonds are not cooperative.

Lasalocid metal salts were combined with 1 : 1 lithium and 2:2 potassium, rubidium, and cesium to form complexes. The nature of the lasolocid salt complexes was studied in a solid and chloroform by FTIR spectroscopy in the middle and far IR regions. The process of the complexation of lithium was also studied by ⁷Li-NMR. In chloroform a 1 : 1 complex of lasalocid and Li⁺ ions was formed. Continuous absorption was observed in the far FTIR spectrum of this complex. It indicated large Li⁺ polarizability, which was due to fast fluctuations of the Li⁺ ions in the multiminima potentials, in the monomeric structure. In the lasalocid salt with the other monovalent cations (K⁺, Rb⁺, Cs⁺) 2:2 complexes were formed in which the cations showed cation polarizability, which strongly depended on the mass and the radius of the cations. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 173–182, 2001

FTIR and NMR of 1H, 13C, 11B, 7Li and 23Na nuclei were used for the study of the complexation of Li+ and Na+ cations by three tris(oxaalkyl) borates. The NMR techniques proved the formation of complexes and the fluctuation of Li+ and Na+ cations in the respective channels formed by three oxaalkyl chains. In the FTIR spectra of Li+ complexes with three tris(oxaalkyl) borates, continuous absorption in the far-infrared region indicates the fast fluctuations of Li+ ion between O atoms of the channels. The dependence of the continua shape on the length of the channels, i.e., the number of minima in the multiminima potentials, demonstrates that the fluctuation of Li+ ion occurs along the channel. Owing to the larger mass and diameter of the Na+ cation in the Na+–tris(oxaalkyl) borate complexes, only systems with longer channels show a large Na+ polarizability due to the fast fluctuation of Na+ cations in a multiminima potential.

The mono- as well as the di-Mannich bases of 5,5′-dimethoxy-2,2′-biphenol are studied by FT-IR spectroscopy. It is shown that in these bases the protons remain localized at the phenol O atom. This result is in contrast to those obtained earlier for more acidic biphenols in which the protons are not localized but fluctuate and the relevant hydrogen bonds show large polarizability. An intense infrared continuum in the FT-IR spectrum of the mono-protonated di-Mannich base of 5,5′-dimethoxy-2,2′-biphenol demonstrates that the intramolecular hydrogen bond in this compound shows large proton polarizability.