- Ligand-Mediated Photophysics Adjustability in Bis-tridentate Ir(III) Complexes and Their Application in Efficient Optical Limiting Materials
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A family of novel bis-tridentate Ir(III) complexes (Ir1-Ir5) incorporating both functional N?C?N-type ligands (L1-L5) and N?N?C-type ligand (L0) were synthesized attentively and characterized scientifically. The crystalline structures of Ir1, Ir3 and Ir4 were resoundingly confirmed by XRD. With the aid of experimental and theoretical methods, their photophysical properties at transient and steady states were scientifically investigated. The broadband charge-transfer absorption for these aforementioned Ir(III) complexes is up to 600 nm as shown in the UV-visible absorption spectrum. The emission lifetimes of their excited states are good. Between the visible and near-infrared regions, Ir1-Ir5 possessed powerful excited-state absorption. Hence, a remarkably robust reverse saturable absorption (RSA) process can occur once the complexes are irradiated by a 532 nm laser. The RSA effect follows the descending order: Ir3 > Ir5 > Ir4 ≈ Ir1 > Ir2. To sum up, modifying electron-donating units (-OCH3) and large ?-conjugated units to the pyridyl N?C?N-type ligands is a systematic way to markedly raise the RSA effect. Therefore, these octahedral bis-tridentate Ir(III) complexes are potentially state-of-the-art optical limiting (OPL) materials.
- Liu, Rui,Lu, Jiapeng,Pan, Qianqian,Zhu, Hongjun,Zhu, Senqiang
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p. 12835 - 12846
(2021/09/13)
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- Heteroleptic Ir(III) phosphors with bis-tridentate chelating architecture for high efficiency OLEDs
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A bis-tridentate iridium complex represented by a formula (I): where R3 to R8, R21 to R23, R9, R10, X1, X2, and X3 are as defined in the specification.
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- Luminescent iridium(III) complexes with N^C^N- coordinated terdentate ligands: Dual tuning of the emission energy and application to organic light-emitting devices
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A family of complexes (1a-3a and 1b-3b) was prepared, having the structure Ir(N^C^N)(N^C)Cl. Here, N^C ^N represents a terdentate, cyclometallating ligand derived from 1,3-di(2-pyridyl)benzene incorporating CH3 (1a,b), F (2a,b), or CF3 (3a,b) substituents at the 4 and 6 positions of the benzene ring, and N^C is 2-phenylpyridine (series a) or 2-(2,4-difluorophenyl) pyridine (series b). The complexes are formed using a stepwise procedure that relies on the initial introduction of the terdentate ligand to form a dichloro-bridged iridium dimer, followed by cleavage with the N^C ligand. 1H NMR spectroscopy reveals that the isomer that is exclusively formed in each case is that in which the pyridyl ring of the N ^C ligand is trans to the cyclometallating aryl ring of the N ^C^N ligand. This conclusion is unequivocally confirmed by X-ray diffraction analysis for two of the complexes (1b and 3a). All of the complexes are highly luminescent in degassed solution at room temperature, emitting in the green (1a,b), blue-green (2a,b), and orange-red (3a,b) regions. The bidentate ligand offers independent fine-tuning of the emission energy: for each pair, the "b" complex is blue-shifted relative to the analogous "a" complex. These trends in the excited-state energies are rationalized in terms of the relative magnitudes of the effects of the substituents on the highest occupied and lowest unoccupied orbitals, convincingly supported by time-dependent density functional theory (TD-DFT) calculations. Luminescence quantum yields are high, up to 0.7 in solution and close to unity in a PMMA matrix for the green-emitting complexes. Organic light emitting devices (OLEDs) employing this family of complexes as phosphorescent emitters have been prepared. They display high efficiencies, at least comparable, and in some cases superior, to similar devices using the well-known tris-bidentate complexes such as fac-Ir(ppy)3. The combination of terdentate and bidentate ligands is seen to offer a versatile approach to tuning of the photophysical properties of iridium-based emitters for such applications.
- Brulatti, Pierpaolo,Gildea, Richard J.,Howard, Judith A. K.,Fattori, Valeria,Cocchi, Massimo,Williams, J. A. Gareth
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experimental part
p. 3813 - 3826
(2012/04/23)
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- Facile synthesis and characterization of phosphorescent Pt(N ^C^N)X complexes
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In order to investigate the ground state and excited state properties of Pt(N^C^N)X, we have prepared a series of Pt complexes, where N^C^N aromatic chelates are derivatives of m-di(2-pyridinyl)benzene (dpb) and X are monoanionic and monodentate ancillary ligands including halide and phenoxide. Facile synthesis of platinum m-di(2-pyridinyl)benzene chloride and its derivatives, using controlled microwave heating, was reported. This method not only shortened the reaction time but also improved the reaction yield for most of the Pt complexes. Two Pt(N^C^N)X complexes have been structurally characterized by X-ray crystallography. The change of functional group does not affect the structure of the core Pt(N^C^N)Cl fragment. Both molecules pack as head-to-tail dimers, each molecule of the dimer related to the other by a center of inversion. The electrochemical studies of all Pt complexes demonstrate that the oxidation process occurs on the metal-phenyl fragment and the reduction process is associated with the electron accepting groups like pyridinyl groups and their derivatives. The maximum emission wavelength of the Pt(N^C^N)X complexes ranges between 471 and 610 nm, crossing the spectrum of visible light. Most of the Pt complexes are strongly luminescent (Φ = 0.32-0.63) and have short luminescence lifetimes (τ = 4-7 μs) at room temperature. The lowest excited state of the Pt(N ^C^N)X complexes is identified as a dominant ligand-centered 3π-π* state with some 1MLCT/3MLCT character, which appears to have a larger 1MLCT component than their bidentate and tridentate analogs. This results in a high radiative decay rate and high quantum yield for Pt(dpb)Cl and its analogs. However, the excited state properties of the Pt(N^C ^N)X complexes are strongly dependent on the nature of the electron-accepting groups and substituents to the metal-phenyl fragment. A rational design will be needed to tune the emission energies of the Pt(N ^C^N)X complexes over a wide range while maintaining their high luminescent efficiency.
- Wang, Zixing,Turner, Eric,Mahoney, Vanessa,Madakuni, Sijesh,Groy, Thomas,Li, Jian
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experimental part
p. 11276 - 11286
(2011/02/27)
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- METAL COMPLEX COMPOUND AND ORGANIC ELECTROLUMINESCENT DEVICE USING SAME
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Provided are an organic electroluminescence device whose wavelength of light emission is short and which can emit blue light having a high color purity, and a metal complex compound for realizing the device. The metal complex compound is of a specific str
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Page/Page column 19
(2008/12/08)
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