Study of the substituent groups effect on the room-temperature phosphorescent emission of fluorene derivatives in solution

We present here the first study of the effect of substituent groups and the chemical structure of fluorene derivatives on phosphorescent emission. A group of fluorene derivatives have been studied with a new methodology of room-temperature phosphorescence emission called heavy atom induced room-temperature phosphorescence (HAI-RTP). This methodology makes use of RTP emission directly from the compound in fluid solution, without a protective medium but only with the presence of high concentrations of heavy atom perturbers and an oxygen scavenger. These experimental conditions permit sufficient interaction between the perturbers and the phosphors to produce effective population of the triplet states of the latter and, consequently, intense phosphorescent emission. Good deoxygenation conditions are obtained using sodium sulfite as the oxygen scavenger. We show here that it is possible that many fluorene derivatives can exhibit RTP emission in aqueous solutions in the absence of a protective medium. Phosphorescence spectral characteristics of these compounds (excitation and emission wavelengths and lifetime) and the optimization of the chemical variables involved in the phosphorescence phenomenon are reported. Under optimal experimental conditions, calibration graphs and detection and quantification limits in the ng ml−1 level have been established. © 2003 Elsevier B.V. All rights reserved.