Synthesis, structure, and solid-state phosphorescence of heteroleptic platinum(II) complexes bearing iminophenyl and iminophenoxy ligands

Komiya, Naruyoshi; Kashiwabara, Takashi; Iwata, Shotaro

doi:10.1016/j.jorganchem.2013.04.009

Cited by 12 publications

(6 citation statements)

References 63 publications

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“…Compounds 3g , h , which contain a methoxy group at the 2-position together with fluoro substituents at the 3- and 4-positions, also display a small red shift in comparison with the unsubstituted analogues 3e , f . Similar effects in the emission wavelengths due to the presence of fluoro or methoxy substituents have been previously reported. , …”

Section: Resultssupporting

confidence: 87%

Platinum(II) Compounds Containing Cyclometalated Tridentate Ligands: Synthesis, Luminescence Studies, and a Selective Fluoro for Methoxy Substitution

et al. 2014

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Two series of potentially tridentate ligands of formula ArCH=N(CH2)2NMe2 and ArCH=N(CH2)3NMe2 (Ar = C6H5, 2-FC6H4, 4-FC6H4, 2,3,4-F3C6H2) were used to prepare [C,N,N′]-cyclometalated platinum compounds containing either a chloro or a methyl ancillary ligand. The synthesis of the compounds [PtCl{Me2N(CH2)xN=CHR}] (3a−h), via the corresponding compounds [PtCl2{Me2N(CH2)xN=CHAr}] (2), requires drastic conditions and proceeds more easily for ligands derived from N,N-dimethylpropylenediamine (x = 3). Along the process, an unexpected selective nucleophilic substitution of a fluoro for a methoxy substituent took place at the aryl ring for ligands 2,3,4-F3C6H2CH=N(CH2)xNMe2. The syntheses of compounds [PtMe{Me2N(CH2)xN=CHR}] (4a−h) using [Pt2Me4(μ-SMe2)2] as a precursor took place for all ligands under relatively mild conditions. All compounds were fully characterized, including molecular structure determination for [PtCl{Me2N(CH2)3N=CH(4-FC6H3)}] (3b) and [PtCl{Me2N-(CH2)3N=CH(2-OMe,3,4-F2C6H)}] (3g). The absorption and emission spectra were also studied for the [C,N,N′]-cyclometalated platinum(II) compounds, and all of the compounds were emissive in the solid state and in dichloromethane solution at room temperature (compounds 3) or at 77 K (compounds 4). The size of the [N,N′]-chelate ring and the number and position of the substituents in the aryl ring modulate the intensity and the energy of the emission.

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Section: Resultssupporting

confidence: 87%

Platinum(II) Compounds Containing Cyclometalated Tridentate Ligands: Synthesis, Luminescence Studies, and a Selective Fluoro for Methoxy Substitution

et al. 2014

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“…The platinum satellites for the imine resonances (JHPt ~ 62 Hz) are consistent with other (salicylaldiminato)platinum complexes [18][19][20][21][22][23][24][25][26]. The FT-IR spectra show the expected decrease in the frequency of the C=N bond due to complexation, which is observed as the νC=N stretch shifts from ca.1632 cm -1 for the free ligands to ca.…”

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confidence: 82%

Synthesis, characterization, and anticancer properties of organometallic Schiff base platinum complexes

et al. 2015

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A small family of organometallic platinum complexes containing a chloride, ciscyclooctene, and a Schiff base ligand have been prepared and characterized fully. Three aliphatic amines and four aromatic amines were chosen as representative examples. All complexes were stable in air except for 7, derived from the pinacol-protected 4-aminophenylboronate ester 4-H2NC6H4Bpin (pin = 1,2-O2C2Me4), which decomposed via B-C bond cleavage.Both complex 4 (derived from aniline) and 7 were further characterized by single crystal X-ray diffraction studies and confirmed the square planar nature of the platinum center whereby the chloride ligand lies trans to the deprotonated hydroxyl group of the Schiff base ligand. The imine functionality is trans to the organic cyclooctene group. Complex 3, which contained the longest aliphatic chain studied (an octyl group), was the most promising for inducing apoptosis in the malignant MB231 breast cancer cell line. Conversely, complexes 4-6, which contained aromatic groups, were the most active against Renal Cell Carcinoma (RCC) cell lines. Graphical Abstract: Seven new organometallic (salicylaldiminato)platinum(II) complexes have been prepared, and characterized fully, whereupon six of these new compounds were examined for their in vitro cytotoxic properties against breast cancer cell line MB231 and Renal Cell Carcinoma (RCC) cell lines.

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“…This is a clear indication that consecutive π‐stacking interaction strongly diminishes efficient phosphorescent emission, while the herringbone motif caused by CH–π interactions and “isolated” stacking dimers does not have a negative influence on the solid‐state emission. The beneficial feature of CH–π interactions in solid‐state emission has also been observed in the high quantum efficiencies and heat‐resistance properties of heteroleptic platinum(II) complexes bearing iminophenyl and iminophenoxy ligands 14. The amorphous solid 1 e has less ordered molecular aggregation in which coordination planes are randomly dispersed, as shown in Figure 10 c.…”

Section: Resultsmentioning

confidence: 88%

“…The low heatresistance properties of these crystals (1 d: F 298K/ F 77K = 0.31; 1 e: F 298K/ F 77K = 0.26; 1 f: F 298K/ F 77K = 0.12) are attributable to weak molecular constraints within the crystals, in which each molecular unit is poorly bound with 1D regional offset stacking and van der Waals interactions. [14] The amorphous solid 1 e has less ordered molecular aggregation in which coordination planes are randomly dispersed, as shown in Figure 10 c. The quantum efficiency of amorphous 1 e at 77 K (F 77K = 0.22) is much higher than that of thermodynamic crystals of 1 e (F 77K = 0.08), which can be ascribed to the inhibition of energy dispersion by molecular alignment with less stacking. Thus, the "isolated" form of the p-stacking dimer formed inside the crystal lattice ( Figure 8 d and 9d) does not significantly affect the inhibition of solidstate emission.…”

Section: C1a C H T U N G T R E N N U N G (Unit A)) and 285 (H6amentioning

confidence: 96%

“…The beneficial feature of CH-p interactions in solid-state emission has also been observed in the high quantum efficiencies and heat-resistance properties of heteroleptic platinum(II) complexes bearing iminophenyl and iminophenoxy ligands. [14] The amorphous solid 1 e has less ordered molecular aggregation in which coordination planes are randomly dispersed, as shown in Figure 10 c. The quantum efficiency of amorphous 1 e at 77 K (F 77K = 0.22) is much higher than that of thermodynamic crystals of 1 e (F 77K = 0.08), which can be ascribed to the inhibition of energy dispersion by molecular alignment with less stacking. The significant decrease in the emission efficiency and intensity of amorphous solid 1 e at 298 K (F 298K /F 77K = 0.09, Figure 3 c), that is, heatquenchable property, is attributed to the high molecular mobility caused by weak molecular constraints due to random aggregation.…”

Section: Wwwchemeurjorgmentioning

confidence: 96%

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Solid‐State Phosphorescence of trans‐Bis(salicylaldiminato)platinum(II) Complexes Bearing Long Alkyl Chains: Morphology Control towards Intense Emission

Komiya

Itami

Naota

2013

Chemistry A European J

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Morphology control for intense solid-state phosphorescence of non-emissive, but potentially emissive crystals of platinum complexes and the mechanistic rationale are described. A series of trans-bis(salicylaldiminato)platinum(II) complexes bearing linear alkyl chains (1a: n=5; 1b: n=8; 1c: n=12; 1d: n=14; 1e: n=16; 1f: n=18) was synthesized and the solid-state emission properties were examined by using crystals/aggregates prepared under various precipitation conditions. Crystals of 1e, prepared using "kinetic" conditions including rapid cooling, high concentrations, and poor solvents, emit intensive yellow phosphorescence (λ(max)=545 nm) under UV irradiation at 298 K with an absolute quantum efficiency of 0.36, whereas all the crystals of 1a-1f prepared using "thermodynamic" conditions including slow cooling, low concentrations, and good solvents were either non- or less emissive with Φ(298K) values of 0.12 (1a), 0.11 (1b), 0.10 (1c), 0.07 (1d), 0.02 (1e), and 0.02 (1f) under the same measurement conditions. The amorphous solid 1e, prepared by rapid cooling and freeze-drying, was also non-emissive (Φ(298K)=0.02, 0.02). Temperature-dependent emission spectra showed that the kinetic crystals of 1e exhibit high heat-resistance towards emission decay with increasing temperature, whereas the amorphous solid 1e is entirely heat-quenchable. This is a rare example of the change from a non-emissive crystal into a highly emissive crystal by morphology control through crystal engineering. Emission spectra and powder X-ray diffraction (XRD) patterns of the emissive, kinetic crystals of 1e are clearly distinct from those of the less emissive, thermodynamic crystals of 1a-1f. Single-crystal XRD unequivocally establishes that the thermodynamic crystals of 1d have a multilayered lamellar structure supported by highly regulated, consecutive π-stacking interactions between imine moieties, whereas the kinetic crystals of 1e have a face-to-edge lamellar structure with less stacking. These results lead to the conclusion that 1) morphology control of long-chained complexes exclusively generates a metastable herringbone-based lamellar packing motif that exhibits intense emission and high heat-resistance, while 2) a thermodynamically stable, highly regulated, consecutive stacking motif is unfavorable for solid-state emission.

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Synthesis, structure, and solid-state phosphorescence of heteroleptic platinum(II) complexes bearing iminophenyl and iminophenoxy ligands

Cited by 12 publications

References 63 publications

Platinum(II) Compounds Containing Cyclometalated Tridentate Ligands: Synthesis, Luminescence Studies, and a Selective Fluoro for Methoxy Substitution

Platinum(II) Compounds Containing Cyclometalated Tridentate Ligands: Synthesis, Luminescence Studies, and a Selective Fluoro for Methoxy Substitution

Synthesis, characterization, and anticancer properties of organometallic Schiff base platinum complexes

Solid‐State Phosphorescence of trans‐Bis(salicylaldiminato)platinum(II) Complexes Bearing Long Alkyl Chains: Morphology Control towards Intense Emission

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