COMPARTMENTAL ANALYSIS OF THE FLUORESCENCE DECAY SURFACE OF THE EXCIPLEX FORMATION BETWEEN 1-METHYLPYRENE AND TRIETHYLAMINE

The rate constant values for exciplex formation between 1-methylpyrene and triethylamine in toluene at room temperature were obtained by global compartmental analysis of the fluorescence decay surface measured as a function of triethylamine concentration. The following values were determined: k01 = (5.97 +/- 0.01) x 10(6) s-1, k21 = (6.54 +/- 0.19) x 10(8) s-1 M-1, k02 = (4.75 +/- 0.06) x 10(7) s-1, k12 = (1.86 +/- 0.06) x 10(8) s-1. There is no evidence for ground-state aggregates between 1-methylpyrene and triethylamine within the concentration range of triethylamine (up to 0.107 M) used in this study. The rate constant of exciplex formation k21 was found to be less than diffusion controlled. This can be rationalized in terms of structural changes at the nitrogen of triethylamine in the course of exciplex formation.