The Photophysical Properties of Iridium(III) and Osmium(II) Complexes Containing Isoquinoline Family Ligands
Date Issued
2009
Date
2009
Author(s)
Chan, Tzu-Ying
Abstract
The purpose of this study is to discuss the photophysical properties of Iridium(III) and Osmium(II) complexes containing isoquinoline family ligands. The first chapter introduces the basic principles of light absorption and the emission of the molecule. The instrumental setups and principles of operation are also presented. With these fundamental conceptions in mind, we will discuss three topics in the following chapters.irst of all, we report the design concept of a series of emissive Ir(III) complexes employing ancillary P^O chelate, for which its PPh2 fragment is well known for the excellent π-accepting characteristics and classified as one of the strong field ligand in the second chapter. These Ir(III) complexes, bearing the chromophore ligand pyridine (ppy), isoquinoline (piq) and quinazoline (nazo) respectively, exhibit green-to-red photoluminescence with moderate to high quantum efficiencies in the degassed fluid state and bright emission in solid state. The photophysical properties and application of these Ir(III) phosphorescent emitters for highly efficient, long-life organic light-emitting diodes are discussed in detail.n the third chapter, we would concentrate on the photophysical properties of a series of Os(II) complexes bearing isoquinoline-triazolate and isoquinoline-pyrazolate moieties respectively. These Os(II) complexes show salient dual emissions consisting of fluorescence and phosphorescence. The yield of phosphorescence is significantly increased as tuning the excitation wavelength from long to short wavelength in common solvents; that is excitation wavelength dependent. The results are rationalized by the increase of metal-ligand-charge-transfer (MLCT) contribution in the highly excited states, drastically enhancing the spin-orbit coupling and hence the intersystem crossing. This observation, being against Kasha’s rule, is also opposites of the well established photophysical phenomena.inally, the last chapter presents the chemiluminescence for the decomposition of 1,4-dimethylnaphthalene endoperoxide and 9,10-diarylanthracence endoperoxide. We observed singlet oxygen 1∆g->3Σg− infrared emission at maxima 1275 nm for the thermal decomposition of endoperoxide in solutions. The results demonstrate that O2 is eliminated in the 1∆g state upon endoperoxide decomposition on the ground state surface. The thermoluminescence spectra of 9,10-diarylanthracene endoperoxide were observed at higher temperature in comparison with 1,4-dimethylnaphthalene endoperoxide. In addition, the rate constants for the disappearance of endoperoxides were found to be dependent on temperature. The activation parameters (∆E‡, A) as well as the rate constants and half life at various temperatures were also mentioned.
Subjects
Iridium
Osmium
photophysical properties
phosphorescence
Type
thesis
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