Correlation of electronic and vibrational properties with the chiro-optical activity of polyfluorene copolymers.

The rationale of this paper is to shed some light on the origin of the optical response of two similar chiral fluorene copolymers in correlation with their vibrational modes, to understand how a chiral center placed in a ramification affects the optical properties of the main chain. Various spectroscopic ellipsometric techniques, in the scope of the Stokes theory were used to characterize the optical-vibrational behavior of the polyfluorenes: ellipsometry in emission (EE), transmission (TE), and Raman (ERS). The results showed that the optical activity and the emission of the circularly polarized light depends substantially on the interaction of the chiral carbon in the ramification and the main chain through specific optically active vibrational modes, for each sample.

Blending as a Strategy to Attain Chiro-Optically Activity Polymers.

Two copolymers, one containing a chiral center and another without any asymmetric site are studied regarding their chiro-optical properties. The pure polymers do not show any signal of chiro-optical activity, only a smooth line is observed in the circular dichroism spectra, even for the chiral material. However, blends containing the achiral one as a major component show striking chiro-optical activity, originating by stable supramolecular structures whose size and shape remain unchanged, regardless of the blend composition.

Temperature effect on the electron-vibrational mode coupling of a fully conjugated polyfluorene derivative.

Photoluminescence (PL) and electroluminescence (EL) spectra were used to probe the thermal relaxation processes of the poly(9,9'-n-dihexyl-2,7-fluorenediiylvinylene-alt-1,4-phenylenevinylene) (LaPPS16) electroluminescent polymer. A theoretical model of molecular excitons and Franck-Condon transitions were used to analyze the line shape of the radiative transitions. It was possible to correlate directly the electron-vibrational mode coupling, i.

Light emission of a polyfluorene derivative containing complexed europium ions.

The photophysical properties of a new alternating copolymer containing fluorene, terpyridine, and complexed sites with trivalent europium (Eu(3+)) ions (LaPPS66Eu) were investigated, using the non-complexed backbone (LaPPS66) and a low molecular weight compound of similar chemical structure of the ligand/Eu(3+) site (LaPPS66M) as a model compound. The analogous gadolinium complex (LaPPS66Gd) was also synthesized to determine the triplet state of the complex. (1)H and (13)C nuclear magnetic resonance (NMR) analysis, Fourier transform infrared (FT-IR) spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES), elemental analyses, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) characterized the chemical structure and thermal properties of the synthesized materials.