Phosphorescence Quenching of Dyes Adsorbed to Silica ThinLayer Chromatography Plates

We describe photoluminescence (PL) quenching experiments by oxygen for a series of transition metal dyes adsorbed to commercial silica thin-layer chromatography plates. These TLC plates have been used by others as rapidly responding PL pressure sensors. The quenching kinetics show interesting differences from the behavior of the same dyes adsorbed to the more well-defined surfaces of SBA-15 mesoporous silica particles adsorbed to a thin layer-by-layer polymer film as reported in Chem. Mater. 2005, 17, 3160. The pore size and the pore size distribution are much larger for the TLC silica than for the mesoporous silica. On the TLC silica, the dye PL decay profiles show smaller deviations from an exponential form. One sees larger differences between the intensity and lifetime Stern-Volmer plots, and most surprisingly, the dyes on the surface of the TLC silica are about three times more sensitive to quenching by oxygen.