Carboxylic acid carbonyl-associated bands

In a series of works, Tokura and coworkers have systematically studied the CD induced in a number of carboxylic acids through their association with optically active amines [14-17]. Salts of 1 1 stoichiometry were formed as contact ion pairs, with limiting values normally being obtained for the observed ellipticities at equivalent molar amounts. The degree of salt formation could be related to the polarity of the solvent medium, as has been summarized in Table 1. The data in the table illustrate that, as the degree of solvent polarity increases, the limiting ellipticity induced in the carboxylate carbonyl band decreases. 

FTIR has been mainly used to obtain structural details of films and to monitor intercalation of metal ions into the film structure and the subsequent reactions of the films with dihydrogen chalcogenides. Both transmission (FTIR-T) and reflection-absorbance (FTIR-RA) modes have been utilized. For the most part these studies have involved films of fatty acids with divalent metal ions. The key features of the FTIR spectra of these films include the asymmetric and symmetric stretching modes of the carboxylate group vs(C02-) and va(C02 ), associated with the M2+/carboxylate complex, and the carbonyl stretching mode v(C=0) of the proton-ated fatty acid. The disappearance of the v(C02 ) (1500-1600 cm-1) and appearance of the v(C=0) bands (—1700 cm-1), concurrent with the formation of the metal chalcogenide and regeneration of the fatty acid, have been used to evaluate... 

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