The Influence of Surface Hydroxyls on Catalyzed Tetrakis(dimethylamino)ethylene Chemiluminescence

The chemiluminescent reaction of tetrakis(dimethylamino)ethylene (TDE) with oxygen was investigated as a means of characterizing surface hydroxyls on MgO. The types and quantities of surface hydroxyl groups on MgO following different pretreatment procedures were studied with FT-IR and triethylaluminum (AIEt(3)) titration. The emission intensity vs. reaction time curve for TDE chemiluminescence was then interpreted based on the types of hydroxyl groups present. Higher emission intensity was detected from TDE chemiluminescence on MgO surfaces rich in lower coordinated isolated OH (especially 4-coordinated isolated OH), suggesting that isolated hydroxyl groups catalyzed TDE chemiluminescence. An unusual shape in the intensity curve was noted for many samples, where intensity first decreased, then increased until it reached a local maximum, and then decreased to zero. This shape was attributed to the fort-nation of quenchers and the eventual separation of the polar quenching species from the nonpolar TDE phase. The number of hydroxyl groups on an MgO sample affected the time at which the local maximum was noted. The more hydroxyls, the earlier the maximum was noted, likely because the hydroxyls sped up TDE reaction and formation of quenching species.