Greenish-Yellow-, Yellow-, and Orange-Light-Emitting Iridium(III) Polypyridyl Complexes with Poly(e-caprolactone)–Bipyridine Macroligands
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Holder, Elisabeth; Marin, Veronica; Alexeev, Alexander; Schubert, Ulrich S.
- Abstract:
- A set of novel greenish-yellow-, yellow-, and orange-light-emitting polymeric
iridium(III) complexes were synthesized with the bridge-splitting method. The
respective dimeric precursor complexes, [Ir(ppy)2-u-Cl]2 (ppy u 2-phenylpyridine) and
[Ir(ppy–CHO)2-u-Cl]2 [ppy–CHO u 4-(2-pyridyl)benzaldehyde], were coordinated to
2,2'-bipyridine carrying poly(e-caprolactone) tails. The resulting emissive polymers
were characterized with one-dimensional (1H) and two-dimensional (1H–1H correlation
spectroscopy) nuclear magnetic resonance and infrared spectroscopy, gel permeation
chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass
spectrometry, and the successful coordination of the iridium(III) centers to the 2,2'-
bipyridine macroligand was revealed. The thermal behavior was studied with differential
scanning calorimetry and correlated with atomic force microscopy. Furthermore,
the quantitative coordination was verified by both the photophysical and electrochemical
properties of the mononuclear iridium(III) compounds. The photoluminescence
spectra showed strong emissions at 535 and 570 nm. The color shifts depended on the
substituents of the cyclometallating ligands. Cyclic voltammetry gave oxidation potentials
of 1.23 V and 1.46 V. Upon the excitation of the films at 365 nm, yellow light was
observed, and this could allow potential applications in light-emitting devices.
- Year:
- 2005
- Type of Publication:
- Article
- Keywords:
- atomic force microscopy AFM; bipyridine macroligands; differential scanning calorimentry DSC; light emitting iridium III compounds; poly e caprolactone; ring opening polymerization; yellow light emitting films
- Journal:
- Journal of Polymer Science: Part A: Polymer Chemistry
- Volume:
- 43
- Pages:
- 2765 - 2776