How does the β-ionone effect the spectra of chlorophyll and the excitation energy transfer in solution

This paper presents the excitation spectra and fluorescence spectra of mixed solution containing chlorophyll a(Chla), chlorophyll b(Chlb) and beta-ionone of different concentration, investigates the spectral changes of Chla and Chlb caused by beta-ionone through optimizing the frontier orbital of Chl-beta-ionone compound, and calculates the energy transfer rate between Chla and Chlb by means of the fluorescence Gauss decomposition. The results show that the beta-ionone interacts with Chl mainly via the connection between the magnesium atom in Chl molecule and the carbonyl in beta-ionone molecule. The formation of Chl-beta-ionone compound changes the charge distribution of Chl so greatly that it leads to the red-shift of the excitation spectra and blue-shift of the fluorescence spectra of Chls. Also in the compound the electronic energy located on carbon double bond of beta-ionone can be transferred to Chl molecule by the MgaEuro broken vertical bar O bond, which enhances the fluorescence intensity greatly. The calculation of the excitation energy transfer (EET) rate indicates that a small amount of beta-ionone can promote the EET between Chla and Chlb.