Multi-conformational monomer and dimer steady-states in domains of a few molecules: the consequences on the phosphorescence emission bands

Dropcast films of very low concentration domains of phenazine 1,2,3-triazole molecules, blended in a Zeonex matrix, were studied by steady-state fluorescence as a function of temperature. These domains, randomly spread in the volume of the films, presented emission characteristics of singlet and triplet states coming from different molecular conformations. Emissions of singlet monomers, dimers or more complex aggregates, as well two distinct triplet phosphorescent bands, were observed to appear concomitantly or in isolated forms. From the analysis of the experimental results, the additional red-shifted phosphorescent band appeared as a consequence of the formation of dimer and/or more complex aggregated states. The emission characteristics of both phosphorescent bands were classified as coming from ensembles of a few interactive molecules. This statement was assumed based on the absence of replica modes of vibrational spin–orbit interactions.