Light emission of a polyfluorene derivative containing complexed europium ions

Abstract

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. A level of Eu(3+) insertion of 37% (molar basis) in the polymer backbone was achieved. The photoluminescence studies were performed in the solid state showing the occurrence of polymer-to-Eu(3+) energy transfer brought about by the spectral overlap between the absorption spectra of the Eu(3+) complex and the emission of the polymer backbone. A detailed theoretical photoluminescence study performed using time-dependent DFT (TD-DFT) calculations and the recently developed LUMPAC luminescence package is also presented. The high accuracy of the theoretical calculations was achieved on comparison with the experimental values. Aiming at a deeper level of understanding of the photoluminescence process, the ligand-to-Eu(3+) intramolecular energy transfer and back-transfer rates were predicted. The complexed materials showed a dominant pathway involving the energy transfer between the triplet of the dbm (dibenzoylmethane) ligand and the (5)D1 and (5)D0 Eu(3+) levels.

Magnetic properties of a polyfluorene derivative containing complexed neodymium ions

“…It is worth mentioning that the increase in the glass transition of 132 °C in the LaPPS75 to the 192 °C in the LaPPS75Nd (Fig. S2 in the Supporting Information) indicating a chain stiffening by the ion incorporated to the backbone . Also, the metallopolymer shows two glass transitions, one of which matches that of the pristine, noncomplexed material and is therefore qualitatively consistent with the relatively low‐complex content.…”

“…LaPPS75M was synthesized following the procedure described in elsewhere . Briefly, 2,2′‐6′,2″‐terpyridine (0.080 g, 0.343 mmol), dibenzoylmethane (0.231 g, 1.029 mmol) and 0.2 mL of triethylamine were dissolved in dry THF (20 mL) under argon.…”

Looking for the Origin of Allosteric Cooperativity in Metallopolymers

“…On the contrary, the less studied lanthanide‐containing metallopolymers belonging to Type I and Type II categories are compatible with the complete or partial filling of the available sites with one or different lanthanide complexes, this without altering the polymeric structures (Figure ). Polynuclear systems with programmed sequences of (open‐shell) metal ions thus become available, a key step to push further ahead with current limits of optical sensing, directional light‐downshifting and energy‐transfer light‐upconversion . As a starting point for bringing Type I or Type II metallopolymers L N within the frame of chemical control, one can benefit from the fact that the thermodynamics of metal loading in these linear metallopolymers is easily caught by a simple model (Figure a), which considers only two free energy parameters: the intermolecular affinity of a single site for the entering metal, M, in the polymer L N and the energetic penalty >0, or benefit <0, produced by a bound site for the fixation of a second metal to an adjacent free site in the polymer L N .…”

Interplay among electronic characteristics, morphology and device efficiency in three fluorene alternated copolymers

“…Fluorene was chosen due to its low lying HOMO level which is particularly interesting to reach a high open circuit voltage (V oc ). The perfectly alternated configuration was provided by employing the Suzuki cross coupling polycondensation reaction [6].…”