Effective inclusion of chlorophyllous pigments into mesoporous silica modified with alpha,omega-diols

FSM-type mesoporous silica modified with various diols was utilized as an i norganic medium for immobilizing chlorophyll a (Chl a) without denaturation . The energy transfer from Chl b to Chl a in the mesopores was also observe d for the first time. Silanol groups on the mesoporous silica were esterifi ed with diols, and this was confirmed by C-13 MAS NMR, IR, N-2 adsorption, and elemental analysis. The suppression of the pigment degradation in modif ied FSM was confirmed by both visible absorption spectroscopy of the FSM/Ch l compounds and the analysis of the extracts from FSM/Chl by high-performan ce liquid chromatography. The fluorescence emission bands of Chl a and Chl b in FSM modified with 1,6-hexanediol appeared at 672 and 654 rim, respecti vely. In the FSM/Chl containing both Chl a and Chl b, the emission band due to Chl b was decreased whereas the band due to Chl a was increased. This i s in sharp contrast to the emission spectrum of an acetone solution contain ing both of Chls, implying energy transfer from Chl b to Chl a in modified mesoporous silica.