Fluorescence ''turn-on'' probe for the selective detection of water in organic solvents based on functionalized mesoporous silica.

A fluorescence ''turn-on'' probe, namely, TTA-SBA-15, for the selective detection of water (HO) was designed by grafting terthiophene fluorophore onto ethylenediamine functionalized mesoporous SBA-15 silica. The maximum fluorescence emission peak of TTA-SBA-15 ranged from 462 nm (toluene) to 525 nm (methanol) in various organic solvents. No fluorescence was observed in HO due to the donor-excited photoinduced electron transfer mechanism, in which terthiophene acted as the donor and the amino group acted as the acceptor. Upon adding trace amounts of HO into the TTA-SBA-15 suspensions dispersed in various organic solvents, TTA-SBA-15 was successfully applied as a ''turn-on'' fluorescent probe for the quantitative determination of trace HO in organic solvents with high sensitivity and low detection limit. To demonstrate the selective detection mechanism of TTA-SBA-15 for HO, the fluorescent spectra of two control materials (TT-SBA-15 and PyA-SBA-15) were also investigated in HO and various organic solvents. The experimental results indicated that the terthiophene fluorophore and amine functional group on TTA-SBA-15 contributed to the HO selectivity, highlighting the structure-activity relationships in developing organic functionalized mesoporous silica for potential applications.