Forbidden Electronic Transitions between the Singlet Ground State and the Triplet Excited State of Pt(II) Complexes

Gy, Zheng; Dp, Rillema; DePriest, Jeffrey C.; Woods, Clifton

doi:10.1021/ic980324c

Cited by 27 publications

(21 citation statements)

References 12 publications

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“…This implies that prior phosphine dissociation from [Pt(2,2 -bph)(PEt 3 ) 2 ] (44) is not a prerequisite for H 2 addition. The reductive elimination of biphenyl from trans-[PtH(␣-bph)(PEt 3 ) 2 ] was inhibited by added phosphine.…”

Section: Catalysis By Metal 22 -Biphenyl Complexesmentioning

confidence: 99%

“…the now popular 2-phenylpyridine complexes mentioned in the Introduction [3,4]. Rillema and co-workers have extensively studied the absorption and emission properties of a number of Pt(2,2 -bph) complexes with the mono-and bidentate ligands, pyridine, acetonitrile, ethylenediamine, CO (27) [23,42], dppm [44,45], and the bridging ligand SEt 2 [41]. Absorption spectra of mono-metallic [Pt(2,2 -bph)(py) 2 ] (52), [Pt(2,2 -bph)(NCMe) 2 ] bonyl complex 27 have been carried out to examine singlet and triplet excited states, and to compare calculated geometries with those from the X-ray crystallographic data previously obtained [42,43].…”

Section: Luminescent Transition Metal 22 -Biphenyl Complexesmentioning

confidence: 99%

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Dibenzometallacyclopentadienes, boroles and selected transition metal and main group heterocyclopentadienes: Synthesis, catalytic and optical properties

Steffen

Ward

Jones

et al. 2010

Coordination Chemistry Reviews

113

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Section: Catalysis By Metal 22 -Biphenyl Complexesmentioning

confidence: 99%

Section: Luminescent Transition Metal 22 -Biphenyl Complexesmentioning

confidence: 99%

Dibenzometallacyclopentadienes, boroles and selected transition metal and main group heterocyclopentadienes: Synthesis, catalytic and optical properties

Steffen

Ward

Jones

et al. 2010

Coordination Chemistry Reviews

113

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“…The complex 1 with bzq ligand shows longer lifetime as compared to that for the complex 2 with ppy ligand, which may be due to a predominant 3 IL contribution in complex 1 26,43. This behavior has been assigned to the existence of a lesser excited-state, singlet-triplet splitting in the complex 1 leading to a higher intersystem crossing quantum yield 50 and longer lifetime 26,27,31,51. Complex 2 shows a higher luminescence quantum efficiency compare to complex 1, which may be related to difference of radiative decay rate (k r ) in these complexes (seeTable 2) 43.…”

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confidence: 92%

Photophysical and DFT studies on cycloplatinated complexes: modification in luminescence properties by expanding of π-conjugated systems

et al. 2015

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To investigate the factors influencing the luminescent properties of cycloplatinated complexes containing aryl and SMe 2 ligands, a detailed study of the photophysical and structural properties of the complexes [Pt(p-MeC 6 H 4 )(C^N)(SMe 2 )], (C^N= benzo[h]quinolate (bzq), 1, or 2-phenylpyridinate (ppy), 2), was conducted in solution and solid state at different temperatures. Density functional theory (DFT) and Time-dependent density functional theory (TD-DFT) investigations were carried out on both the singlet (S 0 , ground) and triplet (T 1 , excited) states of these complexes for explanation of the electronic structures, absorption and emission spectra. In the solid state, these complexes display an intense phosphorescence emission which was red-shifted from 2 to 1 due to expanding of π conjugated system in cyclometalated bzq ligand. These complexes are strongly emissive in 77 K, giving emission peaks similar to those observed at ambient temperature. The complex 1 in deoxygenated CH 2 Cl 2 solution (at low concentration) gave a phosphorescence band which 2 was accompanied by a higher-energy fluorescence band (ascribed to 1 LC transition, centered on bzq ligand), and these bands were disappeared when a concentrated solution or glassy state (77 K) of the complex is in use. On the basis of theoretical calculations, the HOMO level is a mixture of platinum center and ligand orbitals, while the LUMO level is predominantly C^N ligand based. Lowest-lying excited state responsible for the phosphorescence emission (with a significantly long lifetime) is originated from mixed 3 ILCT/ 3 MLCT with some 3 L'LCT excited state and the emission is red shifted to corresponding free cyclometallating ligand.

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“…94À96 This fact has been attributed to the occurrence of a smaller excited-state, singletÀtriplet splitting in the bzq compounds, which leads to higher intersystem crossing quantum yield and longer lifetimes. 95,96 All complexes are emissive in fluid solution and in the glass state. Taking into account that 7 and 8 are only soluble in CH 3 CN, this solvent was chosen for the comparative photophysical study of all of the derivatives (shown in Table 1).…”

Section: ' Introductionmentioning

confidence: 99%

Luminescent Cycloplatinated Complexes Containing Poly(pyrazolyl)-borate and -methane Ligands

et al. 2011

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Cycloplatinated neutral [Pt(C ∧ N){H 2 B(pz) 2 }] (1À3) [C ∧ N = benzoquinolate (bzq), 2-phenylpyridinate (ppy), and 2-phenylquinolate (pq)] and [Pt(pq){HB(pz) 3 }] 10 and cationic [Pt(C ∧ N){H 2 C(pz) 2 }] + (4À6) and [Pt(C ∧ N){HC(pz) 3 }] + (7À9)complexes were synthesized by the reaction of the corresponding precursors [Pt(C ∧ N)(μ-Cl)] 2 with the adequate poly-(pyrazolyl)-borate or -methane ligand. However, the reactions of [Pt(C ∧ N)(μ-Cl)] 2 (C ∧ N = bzq, ppy) with [HB(pz) 3 ] À evolve with BÀN bond cleavage, yielding the binuclear systems [Pt(C ∧ N)(μ-pz)] 2 as a mixture of cis and trans isomers. Complexes were characterized in solution by multinuclear and multidimensional NMR spectroscopy. The solid-state structures of 1, 3, 6, 7À9, and [Pt(bzq)(μ-pz)] 2 were confirmed by X-ray single-crystal studies. The absorption, emission, and electrochemical properties of these complexes are mainly dominated by the nature of the cyclometalated ligand and the charge of the complex. On the basis of TD-DFT calculations (1, 7À9), the lowest-energy absorption for neutral 1 has been ascribed to a mixed 1 ILCT/ 1 MLCT transition, whereas for the cationic 7À9, it is mainly attributed to 1 ILCT combined with some CT to both ligands in 9 ( 1 MLCT/ML 0 CT 9) or to the HC(pz) 3 in 7 and 8 ( 1 ML 0 CT). These compounds are emissive in all media (except 4 and 10 in the solid state at 298 K). In the solid state at 298 K and at 77 K, these complexes display intense phosphorescence, which is typical of monomers. In deoxygenated CH 3 CN solutions at 298 K, phosphorescence is accompanied by higher-energy fluorescence in complexes 1, 4, and 8, which disappears at concentrated solutions and at 77 K. Complex 7 displays a special behavior, observing fluorescence and/or excimer fluorescence only at 298 K and excimeric emission (diluted glasses) and emission from aggregates in concentrated glasses. TD-DFT of the lowest-lying excited states responsible for the phosphorescence of 1 and 7À9 reveals a 3 ILCT origin with a mixed 3 MLCT character for 1 and, in the case of the cationic 7À9, a 3 ILCT transition mixed with 3 ML 0 CT (especially in 8) and with some 3 MLCT in 9. ' INTRODUCTIONCyclometalated square-planar platinum(II) complexes have attracted great interest in recent years due to their luminescent properties 1À12 with potential applications in optoelectronic devices, 2,3,7,10,11,13À25 photocatalysts, 26 and chemical or biochemical sensors. 27À31 Emission from these Pt(II) complexes is typically assigned to ligand-centered ( 3 LC) and/or metal-to-ligand charge-transfer ( 3 MLCT) states, although some degree of ligand-to-ligand 0 charge-transfer ( 3 LL 0 CT) states is also possible. Additionally, the square-planar nature of these complexes facilitates the formation of dimers or aggregates through noncovalent π 3 3 3 π and/or Pt 3 3 3 Pt interplanar stacking interactions, both in the solid state and in solution. 32À44 As a consequence, they exhibit rich photophysical behavior causing a marked red shift relative to the mononuclear emissio...

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Forbidden Electronic Transitions between the Singlet Ground State and the Triplet Excited State of Pt(II) Complexes

Cited by 27 publications

References 12 publications

Dibenzometallacyclopentadienes, boroles and selected transition metal and main group heterocyclopentadienes: Synthesis, catalytic and optical properties

Dibenzometallacyclopentadienes, boroles and selected transition metal and main group heterocyclopentadienes: Synthesis, catalytic and optical properties

Photophysical and DFT studies on cycloplatinated complexes: modification in luminescence properties by expanding of π-conjugated systems

Luminescent Cycloplatinated Complexes Containing Poly(pyrazolyl)-borate and -methane Ligands

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