Modifying Emission Spectral Bandwidth of Phosphorescent Platinum(II) Complexes Through Synthetic Control

Guijie Li, Alicia Wolfe, Jason Brooks, Zhi Qiang Zhu, Jian Li

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The design, synthesis, and characterization of a series of tetradentate cyclometalated Pt(II) complexes are reported. The platinum complexes have the general structure Pt(ppz-O-CbPy-R), where a tetradentate cyclometalating ligand is consisting of ppz (3,5-dimethyl-1-phenyl-pyrazole), CbPy (carbazolylpyridine) components, and an oxygen bridging group. Variations of the R group on the pyridyl ring with various electron withdrawing and donating substituents are shown to have profound effects on the photophysical properties of Pt complexes. Electrochemical analysis indicates that reduction process occurs mainly on the electron-accepting pyridyl group, and the irreversible oxidation process is primarily localized on the metal-phenyl portions. The studies of their photophysical properties indicate that the lowest excited state of the platinum complexes is a ligand-centered 3π-π∗ state with minor to significant 1MLCT/3MLCT character and are strongly dependent on the nature of the electron-accepting pyridyl moiety. A systematic study of the substituent effects on the pyridyl ring demonstrates that the T1 state properties can be tuned by altering the functionality and positions of substituents. Importantly, it is revealed that how the emission spectra of the Pt(II) complexes can be significantly narrowed and why it can be achieved by incorporating an electron-donating group on the 4-position of the pyridyl ring. Most of the Pt(II) complexes reported here are highly emissive at room temperature in dichloromethane solutions (φ = 1.1-95%) and in doped PMMA films (φ = 29-88%) with luminescent lifetimes in the microsecond range (τ = 0.6-13.5 μs in solution and 0.9-11.3 μs in thin film respectively) and λmax = 442-568 nm and 440-544 nm in solution and thin film, respectively. Moreover, these complexes are neutral and thermally stable for sublimation, indicating that they can be useful for display and solid-state lighting applications.

Original languageEnglish (US)
Pages (from-to)8244-8256
Number of pages13
JournalInorganic Chemistry
Volume56
Issue number14
DOIs
StatePublished - Jul 17 2017

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spectral emission
Platinum
platinum
bandwidth
Bandwidth
Electrons
rings
electrons
Ligands
Thin films
ligands
Methylene Chloride
Sublimation
Polymethyl Methacrylate
thin films
sublimation
Excited states
illuminating
emission spectra
Lighting

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

Modifying Emission Spectral Bandwidth of Phosphorescent Platinum(II) Complexes Through Synthetic Control. / Li, Guijie; Wolfe, Alicia; Brooks, Jason; Zhu, Zhi Qiang; Li, Jian.

In: Inorganic Chemistry, Vol. 56, No. 14, 17.07.2017, p. 8244-8256.

Research output: Contribution to journalArticle

Li, Guijie ; Wolfe, Alicia ; Brooks, Jason ; Zhu, Zhi Qiang ; Li, Jian. / Modifying Emission Spectral Bandwidth of Phosphorescent Platinum(II) Complexes Through Synthetic Control. In: Inorganic Chemistry. 2017 ; Vol. 56, No. 14. pp. 8244-8256.
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abstract = "The design, synthesis, and characterization of a series of tetradentate cyclometalated Pt(II) complexes are reported. The platinum complexes have the general structure Pt(ppz-O-CbPy-R), where a tetradentate cyclometalating ligand is consisting of ppz (3,5-dimethyl-1-phenyl-pyrazole), CbPy (carbazolylpyridine) components, and an oxygen bridging group. Variations of the R group on the pyridyl ring with various electron withdrawing and donating substituents are shown to have profound effects on the photophysical properties of Pt complexes. Electrochemical analysis indicates that reduction process occurs mainly on the electron-accepting pyridyl group, and the irreversible oxidation process is primarily localized on the metal-phenyl portions. The studies of their photophysical properties indicate that the lowest excited state of the platinum complexes is a ligand-centered 3π-π∗ state with minor to significant 1MLCT/3MLCT character and are strongly dependent on the nature of the electron-accepting pyridyl moiety. A systematic study of the substituent effects on the pyridyl ring demonstrates that the T1 state properties can be tuned by altering the functionality and positions of substituents. Importantly, it is revealed that how the emission spectra of the Pt(II) complexes can be significantly narrowed and why it can be achieved by incorporating an electron-donating group on the 4-position of the pyridyl ring. Most of the Pt(II) complexes reported here are highly emissive at room temperature in dichloromethane solutions (φ = 1.1-95{\%}) and in doped PMMA films (φ = 29-88{\%}) with luminescent lifetimes in the microsecond range (τ = 0.6-13.5 μs in solution and 0.9-11.3 μs in thin film respectively) and λmax = 442-568 nm and 440-544 nm in solution and thin film, respectively. Moreover, these complexes are neutral and thermally stable for sublimation, indicating that they can be useful for display and solid-state lighting applications.",
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N2 - The design, synthesis, and characterization of a series of tetradentate cyclometalated Pt(II) complexes are reported. The platinum complexes have the general structure Pt(ppz-O-CbPy-R), where a tetradentate cyclometalating ligand is consisting of ppz (3,5-dimethyl-1-phenyl-pyrazole), CbPy (carbazolylpyridine) components, and an oxygen bridging group. Variations of the R group on the pyridyl ring with various electron withdrawing and donating substituents are shown to have profound effects on the photophysical properties of Pt complexes. Electrochemical analysis indicates that reduction process occurs mainly on the electron-accepting pyridyl group, and the irreversible oxidation process is primarily localized on the metal-phenyl portions. The studies of their photophysical properties indicate that the lowest excited state of the platinum complexes is a ligand-centered 3π-π∗ state with minor to significant 1MLCT/3MLCT character and are strongly dependent on the nature of the electron-accepting pyridyl moiety. A systematic study of the substituent effects on the pyridyl ring demonstrates that the T1 state properties can be tuned by altering the functionality and positions of substituents. Importantly, it is revealed that how the emission spectra of the Pt(II) complexes can be significantly narrowed and why it can be achieved by incorporating an electron-donating group on the 4-position of the pyridyl ring. Most of the Pt(II) complexes reported here are highly emissive at room temperature in dichloromethane solutions (φ = 1.1-95%) and in doped PMMA films (φ = 29-88%) with luminescent lifetimes in the microsecond range (τ = 0.6-13.5 μs in solution and 0.9-11.3 μs in thin film respectively) and λmax = 442-568 nm and 440-544 nm in solution and thin film, respectively. Moreover, these complexes are neutral and thermally stable for sublimation, indicating that they can be useful for display and solid-state lighting applications.

AB - The design, synthesis, and characterization of a series of tetradentate cyclometalated Pt(II) complexes are reported. The platinum complexes have the general structure Pt(ppz-O-CbPy-R), where a tetradentate cyclometalating ligand is consisting of ppz (3,5-dimethyl-1-phenyl-pyrazole), CbPy (carbazolylpyridine) components, and an oxygen bridging group. Variations of the R group on the pyridyl ring with various electron withdrawing and donating substituents are shown to have profound effects on the photophysical properties of Pt complexes. Electrochemical analysis indicates that reduction process occurs mainly on the electron-accepting pyridyl group, and the irreversible oxidation process is primarily localized on the metal-phenyl portions. The studies of their photophysical properties indicate that the lowest excited state of the platinum complexes is a ligand-centered 3π-π∗ state with minor to significant 1MLCT/3MLCT character and are strongly dependent on the nature of the electron-accepting pyridyl moiety. A systematic study of the substituent effects on the pyridyl ring demonstrates that the T1 state properties can be tuned by altering the functionality and positions of substituents. Importantly, it is revealed that how the emission spectra of the Pt(II) complexes can be significantly narrowed and why it can be achieved by incorporating an electron-donating group on the 4-position of the pyridyl ring. Most of the Pt(II) complexes reported here are highly emissive at room temperature in dichloromethane solutions (φ = 1.1-95%) and in doped PMMA films (φ = 29-88%) with luminescent lifetimes in the microsecond range (τ = 0.6-13.5 μs in solution and 0.9-11.3 μs in thin film respectively) and λmax = 442-568 nm and 440-544 nm in solution and thin film, respectively. Moreover, these complexes are neutral and thermally stable for sublimation, indicating that they can be useful for display and solid-state lighting applications.

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