Blue-shifted fluorescence spectrum in silica xerogels with incorporation of extract’s leaves

The spectral characteristics of different kind of leaves extracts fluorescence embedded in silica xerogel matrix under structural evolution promoted by heat treatment was studied. We obtain a higher PSII thermostability for extract of leaves, rich in chlorophyll such as spinach, made in darker condition than extract of leaves made in lighter (non-dark) conditions, both embedded in xerogel matrix, which remain bioactive over a very long period of time. In other kind of leaves such geranium, after chlorophyll decomposition the quenching center are formed at temperatures about 800 °C, whereas in buxus sempervirens leaves fluorescing aggregates remain in temperatures as high as 1,000 °C, when their are embedded in silica xerogel matrix. In general blue-shift fluorescence is observed in all cases indicating the PSII denaturizing and formation of fluorescing aggregates in relatively high temperatures.