The spectroscopic (FT-IR, FT-Raman and 1H, 13C NMR) and theoretical studies of cinnamic acid and alkali metal cinnamates

The effect of alkali metals (Li -> Na -> K -> Rb -> Cs) on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (H-1, C-13 NMR) and quantum mechanical calculations. The spectroscopic studies lead to conclusions concerning the distribution of the electronic charge in molecule, the delocalization energy of pi-electrons and the reactivity of metal complexes. The change of metal along with the series: Li -> Na -> K -> Rb -> Cs caused: (1) the change of electronic charge distribution in cinnamate anion what is seen via the occurrence of the systematic shifts of several bands in the experimental and theoretical IR and Raman spectra of cinnamates, (2) systematic chemical shifts for protons H-1 and C-13 nuclei. (c) 2006 Elsevier B.V. All rights reserved.