Effect of High Pressure on the Molecular Structure andπ-Electrons Delocalization of Canthaxanthin as Revealed by Raman Spectra

[摘要] The effect of high pressure on the molecular structure andπ-electron delocalization of canthaxanthin was studied byin situresonance Raman spectroscopy. Changes in the characteristic band frequency and the pressure of canthaxanthin were described. The effect of pressure onπ-electron delocalization was also discussed. Results show that the characteristic bands of canthaxanthin increase and reach high wavenumbers. The correlations between Raman frequency of the three main bands and pressure are listed as follows:ν1(C=C) = 3.43P+ 1512.3,ν2(C-C) = 3.29P+ 1156.1, andν3(CH3) = 2.16P+ 1006.3. The frequency multiplication of canthaxanthin changes as pressure is altered. The pressure effect on theν1(C=C) mode is more susceptible than on theν2(C-C) mode, which can be explained by the fact that theβ-ring twists to a larger angle from the plane of the conjugated main chain under high pressure, leading to a lower degree of theπ-electrons delocalization. The Raman spectra are recovered after the compression-decompression cycle indicating the canthaxanthin has no evident phase change under our experimental conditions.

[学科分类] 光谱学