Excimer Formation of Dimethyl 2,6-Naphthalene Dicarboxylate Embedded in a Poly(methyl methacrylate) Matrix

Abstract

Dimethyl 2,6-naphthalene dicarboxylate (DMN) was embedded in a poly(methyl methacrylate) (PMMA) matrix. According to the molecular weight of the repeating unit of PMMA different samples containing 0.02 up to 8 mol % DMN have been prepared. Starting from 1 mol % DMN content, excimer formation is observed. From time-resolved fluorescence experiments the fluorescence lifetime of the monomer was derived to be 15 ns and the excimer lifetime amounts to 30 ns. It was shown that Förster excitation energy transfer takes place among the DMN monomers and the Förster radius of the monomer was determined by time-resolved fluorescence depolarization experiments to be 23 ± 3 Å. Excitation energy transfer is assumed to be the dominant process for the excimer formation. Using a model of three-dimensional transport among DMN donors until an excimer trap is reached, dimensionless trap concentrations of 0.005 and 0.014 were derived for the samples with 1 and 2 mol % DMN, respectively. For larger DMN concentration the excitation energy transfer between DMN molecules becomes anisotropic.

Photoluminescence of Self-organized Perylene Bisimide Polymers

“…polymers in which several chromophores are linked by flexible segments. [14] Previously we reported the synthesis of polymers P1, P2, and P3 (Figure 1), consisting of alternating segments of perylene bisimide chromophores and polytetrahydrofuran (polyTHF) of different average length (%3, %14, and %33 THF units, respectively). [15] These polymers self organize in solution via p-p stacking of the chromophores.…”

Synthesis, structure and luminescent properties of zinc(II) and Hg(II) complexes with substituted 1,10-phenanthroline

“…The lower energy emission peak is probably from the excimer of 1. PMMA films doped with ligand in different concentrations were made and fluorescence spectra of these films (figure 6) show low energy emission of the ligand in the films is enhanced with increase in doped concentration, which is indicative of the formation of the excimer [20]. The emission maxima of 2a and 2b (430 and 390 nm, respectively) in the solid state are blue shifted compared to their corresponding emission maxima in solution, presumably from …”

Mechanochemistry in Polymers with Supramolecular Mechanophores

“…[35,36] By contrast, diffusion of dye molecules in solid polymers is slow in comparison to the lifetime of the excited states, so that in this environment excimers predominantly arise from preformed ground-state aggregates, which may also display different absorption characteristics than the monomeric species. [37] Early work on the mechanically induced deformation of supramolecular assemblies of chromophores in polymer matrices was inspired by the surprising discovery that solid-state tensile deformation of blends of minute amounts of the highly fluorescent, conjugated polymer poly(2,5-(2-ethylhexyloxy)-p-phenylene ethynylene) (EHO-OPPE) and ultra-high-molecular-weight poly(ethylene) not only led to uniaxial orientation of the conjugated guest molecules along the elongational axis, but also promoted the break-up of small aggregates comprising a few of these molecules into well-individualized structures (Figure 1). [38] This process was monitored by singlemolecule spectroscopy ( Figure 2) and did not cause any noticeable color changes.…”