Blue highly fluorescent boron difluoride complexes based on phthalazine–pyridine

Vuong, Thi Minh Ha; Weimmerskirch-Aubatin, Jennifer; Lohier, Jean‐François; Bar, Nathalie; Boudin, S.; Labbé, Christophe; Gourbilleau, Fabrice; Nguyen, Hien; Dang, Tung T.; Villemin, Didier

doi:10.1039/c6nj00726k

Cited by 19 publications

(12 citation statements)

References 39 publications

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“…XRD studies of similar structures show that the basic oxazaborinin molecule class tends to form π‐π stacking in the solid state, which can lead to fluorescence quenching ,,,,. An approach of introducing bulky side substituents is used to overcome this problem.…”

Section: Resultsmentioning

confidence: 99%

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 XRD studies of similar structures show that the basic oxazaborinin molecule class tends to form π-π stacking in the solid state, [34] which can lead to fluorescence quenching. [13,14,19,20,35] An approach of introducing bulky side substituents is used to overcome this problem. Indeed, the X-ray crystal analysis of compound 4 reveals that the alignment of diethylphosphonate groups between layers reduces the formation of the π-π stacking between phenyl or pyridine rings ( Figure 2) compared to a basic oxazaborinin molecule class.…”

Section: Synthesis Routementioning

confidence: 99%

“…Among the EL materials, four-coordinated organoboron complexes have attracted much attention due to their intense luminescence, high carrier mobility, chemical and thermal stability as well as facile synthetic accessibility. [6,[13][14][15][16][17] Importantly the application of boron instead of transition metals (e. g. iridium, copper etc.) is environmentally and economically preferable.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Oxazaborinin Phosphonate for Blue OLED Emitter Applications

et al. 2019

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A blue‐light emitting material based on a boron complex containing heteroaromatic phosphonate ligand is synthesized and characterized. The Phospho‐Fries rearrangement is used in the synthesis route of the ligand as a convenient method of introducing phosphonate groups into phenols. Structural, thermal and photophysical properties of the resulting oxazaborinin phosphonate compound have been characterized. DFT geometry optimizations were studied as well as the spatial position and symmetry of the HOMO and LUMO. Good thermal stability up to 250 °C enables vacuum deposition methods next to solution processing. Combining the work function with the optical band gap from UV‐Vis measurements shows that band alignment is possible with standard contact materials. Photoluminescence reveals an emission peak at 428 nm, which is suitable for a blue light‐emitter.

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Section: Resultsmentioning

confidence: 99%

Section: Synthesis Routementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Oxazaborinin Phosphonate for Blue OLED Emitter Applications

et al. 2019

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“…Boron-fused structures with bidentate π-conjugated ligands can enhance the rigidity and planarity of molecular frameworks because of their strong coordination ability originating from the electron-acceptor character of boron [12][13][14][15][16]. Thus, boron complexation is recognized as an established tactic for constructing highly-emissive fluorescent dyes [17][18][19][20][21][22][23][24]. Indeed, numerous studies have been accomplished on the development of emissive materials based on boron complexes with rigid and planar skeletons [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

The Design Strategy for an Aggregation- and Crystallization-Induced Emission-Active Molecule Based on the Introduction of Skeletal Distortion by Boron Complexation with a Tridentate Ligand

et al. 2020

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We describe here a new design strategy for obtaining boron complexes with aggregation- and crystallization-induced emission (AIE and CIE, respectively) properties based on the introduction of skeletal distortion. According to our recent results, despite the fact that an almost planar structure and robust conjugation were obtained, the boron azomethine complex provided a slight emission in solution and an enhanced emission in aggregation and crystal. Quantum calculation results propose that unexpected emission annihilation in solution could be caused through intramolecular bending in the excited state. Herein, to realize this unique molecular motion and obtain AIE and CIE molecules, the phenyl quinoline-based boron complexes BPhQ and BPhQm with distorted and planar structures were designed and synthesized, respectively. BPhQm showed emission in solution and aggregation-caused quenching (ACQ, BPhQm: ΦF,sol. = 0.21, ΦF,agg. = 0.072, ΦF,cryst. = 0.051), while BPhQ exhibited a typical AIE and CIE (BPhQ: ΦF,sol. = 0.008, ΦF,agg. = 0.014, ΦF,cryst. = 0.017). The optical data suggest that a large degree of molecular motion should occur in BPhQ after photo-excitation because of the intrinsic skeletal distortion. Furthermore, single-crystal X-ray diffraction data indicate that the distorted π-conjugated system plays a positive role in presenting solid-state emission by inhibiting consecutive π–π interactions. We demonstrate in this paper that the introduction of the distorted structure by boron complexation should be a new strategy for realizing AIE and CIE properties.

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“…However, the possibility of excimer formation through packing usually leads to reduced electroluminescence efficiency and degradation of color purity in such devices . In that context, the color tuning of four‐coordinate organoboron compounds achieved by modifying ligands provides an alternative for the development of new blue emitters , . Even so, there are only a few reports on both efficient and stable blue fluorescent complexes and very little on the theoretical modeling of the emission dynamics.…”

Section: Introductionmentioning

confidence: 99%

New Boron(III) Blue Emitters for All‐Solution Processed OLEDs: Molecular Design Assisted by Theoretical Modeling

et al. 2019

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Luminescent boron(III) complexes have recently been employed as emitters in organic light‐emitting diodes (OLEDs) with reasonable success. They are easy to prepare and sufficiently stable to be used in such devices, being of great interest as a simple molecular emissive layer. Although emitters for this class with all colors have already been reported, highly efficient and stable blue emitters for applications in solution processed devices still pose a challenge. Here, we report the design, synthesis, and characterization of new boron complexes based on the 2‐(benzothiazol‐2‐yl)phenol ligand (HBT), with different donor and acceptor groups responsible for modulating the emission properties, from blue to red. The molecular design was assisted by calculations using our newly developed formalism, where we demonstrate that the absorption and fluorescence spectra can be successfully predicted, which is a powerful technique to evaluate molecular photophysical properties prior to synthesis. In addition, density functional theory (DFT) enables us to understand the molecular and electronic structure of the molecules in greater detail. The molecules studied here presented fluorescence efficiencies as high as Φ = 0.88 and all solution processed OLEDs were prepared and characterized under an ambient atmosphere, after dispersion in the emitting layer. Surprisingly, even considering these rather simple experimental conditions, the blue emitters displayed superior properties compared to those in the present literature, in particular with respect to the stability of the current efficiency.

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Blue highly fluorescent boron difluoride complexes based on phthalazine–pyridine

Abstract: Synthesis and characterization of three blue fluorescent phthalazine–pyridine boron complexes with quantum yields up to 79%.

Cited by 19 publications

References 39 publications

Synthesis and Characterization of Oxazaborinin Phosphonate for Blue OLED Emitter Applications

Synthesis and Characterization of Oxazaborinin Phosphonate for Blue OLED Emitter Applications

The Design Strategy for an Aggregation- and Crystallization-Induced Emission-Active Molecule Based on the Introduction of Skeletal Distortion by Boron Complexation with a Tridentate Ligand

New Boron(III) Blue Emitters for All‐Solution Processed OLEDs: Molecular Design Assisted by Theoretical Modeling

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