Synthesis and Photochemical Properties of Cyclometalated Styryl-substituted 2-Phenylpyridinato Platinum (II) Complexes
Date Issued
2009
Date
2009
Author(s)
Lin, Che-Jen
Abstract
The synthesis, molecular modeling, and photochemical properties of four Pt(II) complexes [(C^N)Pt(O^O)] are reported. C^N is a monoanionic cyclometalating styrene-incorporated phenylpyridine ligand (PyDM, PyDP, PhDM, and PhDP) and O^O is an acetylacetone (acac) ligand. The solid-state structures of PhDP and PtPhDP were characterized by X-ray diffraction. Molecular modeling was carried out with DFT and TD-DFT methods, and photochemical properties were investigated with UV-Vis absorption, steady-state luminescence, and the measurements of trans→cis photoisomerization quantum yield. The lowest singlet excited-state (S1) for all the Pt complexes is of ILCT character and it is more meta-ph ILCT character for PtPhDM and PtPhDP than for PtPyDM and PtPyDP. All PtII complexes show phosphorescence only at 77 K but not at room temperature. The major triplet deactivated pathway is the nonradiative trans→cis isomerization. Furthermore, the excited-state behavior which is independent of the substitution position mainly dictated by the stilbene and azastilbene moiety. The lowest excited state (T1) is an intraligand charge transfer state (3ILCT). The 3ILCT state is localized on the azastilbene moiety for PyDM and PyDP systems but is from aminostilbene to the pyridinium moiety for PhDM and PhDP systems. As a result, the behavior of these systems can be understood by a para vs meta conjugation effect.
Subjects
platinum
stilbene
Type
thesis
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