Fluorescence Resonance Energy Transfer of Fluorescent Molecules in Joint-Linker Type Organic-Inorganic Hybrid Gels

Fluorescence resonance energy transfer (FRET) sensitized emission of perylene by pyrene in a joint-linker type gel is observed for the first time. The joint-linker type organic-inorganic hybrid gels containing pyrene and perylene synthesized from multi-functional cyclic siloxane, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), or cubic silsesquioxane, 1,3,5,7,9,11,13,15-octakis(dimethylsilyloxy)pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as joint molecules, and α,ω-nonconjugated dienes, 1,5-hexadiene (HD), or 1,9-decadiene (DD), as linker molecules, are involved in a photo hydrosilylation reaction with a bis(acetylacetonato)platinum catalyst in a toluene solution of pyrene and perylene. FRET from pyrene (donor) to perylene (acceptor) in the gels is studied quantitatively. The FRET efficiencies (E) of gels containing 300 or 30 x 10^–6 m of pyrene and perylene are about 0.6–0.8 or 0.5, respectively, independent of the monomer concentration. Sensitized acceptor emission is observed in the gels, especially in the gels containing 300 x 10^–6 m of pyrene and perylene molecules. The ratio of the increase of the sensitized acceptor emission to the loss of donor fluorescence, the G factor, is determined to evaluate the efficiency of the sensitized emission of the acceptor in the gels. The G factors of the gels containing 300 or 30 x 10^–6 m of pyrene and perylene molecules are 0.4–0.75 or 0.07-0.1, repectively, and the gels with TMCTS or DD have a slightly higher G factor than gels with POSS or HD. (Figure presented.).