|Title||Investigation of the self-organization of lutein and lutein diacetate by electronic absorption, circular dichroism spectroscopy, and atomic force microscopy|
|Publication Type||Journal Article|
|Year of Publication||2001|
|Authors||Zsila, F, Bikádi, Z, Keresztes, Z, Deli, J, Simonyi, M|
|Journal||Journal of Physical Chemistry B|
|Pagination||9413 - 9421|
Spontaneously forming H- and J-type chiral self-assemblies of lutein and lutein diacetate were studied by means of ultraviolet-visible and circular dichroism spectroscopy (CD). Spectroscopic properties of their thin films has been determined for the first time. Existence of chiral superstructures in both solution and solid phases with opposite and same handedness was demonstrated. The molecular exciton theory and the exciton chirality rule were applied to define both qualitatively and quantitatively the spectral shifts, band shape changes, and the highly intense but quite different excitonic CD activity in the two forms of aggregates. Atomic force microscopy images revealed definite threadlike morphology in lutein diacetate films referring to the formation of a nematic liquid crystal phase which probably exists in the aqueous solution either. On this basis, the vibronically coupled CD bands of lutein diacetate are attributed to an excitonic interaction arised from the twisted nematic layers.