EMISSION OF A BICHROMOPHORIC MOLECULE IN THE PRESENCE OF AN ADDED QUENCHER - STUDY OF THE TIME-RESOLVED FLUORESCENCE BY GLOBAL COMPARTMENTAL ANALYSIS WITH AND WITHOUT THE USE OF A MODEL-COMPOUND

The previously presented bicompartmental models for intramolecular exc ited-state systems with added quencher [Boens et al. J. Phys. Chem. 19 93, 97, 799 and Van Dommelen et al. J. Phys. Chem. 1993, 97, 11738] ar e experimentally investigated by time-resolved fluorescence measuremen ts. The emission of the bichromophore bis(2-pyrenecarboxylic acid) 1,6 -hexanediyl ester was studied in the absence and presence of iodometha ne as a fluorescence quencher. Two different approaches are examined: one where no information is known beforehand and another where the tim e-resolved emission from the model compound hexyl 2-pyrenecarboxylate was used in the fittings. In the first approach, it was possible to ob tain upper and lower limits for the rate constants k(01), k(21), k(02) , and k(12) (see Scheme 1) by analyzing at different preset values of the rate constant k(01). For the other approach, the parameter values of k(01) and k(Q1) were defined by linking these parameters with the c orresponding rate constants of the model compound, whose quenched deca ys were included in the data analysis. For the calculations of the spe cies-associated emission spectra (SAEMS) two different strategies were followed in the data analysis: one where no information from the mode l compound steady-state fluorescence spectra was included and one whic h made use of such information. SAEMS were obtained for both strategie s, but inclusion of the steady-state fluorescence spectra information leads to better defined SAEMS for the locally excited state and excime r emissions.