Enhanced Quantum Yield of Nanographenes Incorporated in Supermicroporous Silicas and the Co-Adsorption Effect of Water Molecules

Nanographene with various molecular sizes was synthesized and incorporated into the size-controlled pores of super-microporous silica (SMPS). It was found that when the pore diameter of the SMPS matched the molecular size of the nanographene, the fluorescence quantum yield was greatly enhanced. Furthermore, co-adsorption of water molecules improved the quantum yield. This improvement is attributed to a suppression of the interaction between the nanographene and silica walls, which lowers the quantum yield. Since nanographene is insoluble in water, it becomes surrounded by water molecules, almost like in aqueous solution. Finally, highly fluorescent solid materials were obtained by incorporating nanographene into SMPS.