Syntheses, crystal structures, chirality and aggregation-induced phosphorescence of stacked binuclear platinum(<scp>ii</scp>) complexes with bridging Salen ligands

Qu, Liangliang; Li, Chunbo; Shen, Guohua; Gou, Fei; Song, Jintong; Wang, Man; Xu, Xuemei; Zhou, Xiangge; Xiang, Haifeng

doi:10.1039/c9qm00105k

Cited by 24 publications

(15 citation statements)

References 74 publications

(114 reference statements)

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“…The UV/visible absorption and phosphorescence data of all binuclear Pt(II) complexes at room temperature are listed in Table S1 and Figures – and (S1–S3 Supporting Information). Except for the circular dichroism (CD) and CPL properties, the optical properties of five pairs of ( S )/( R ) enantiomers are similar (Figures S1–S3), as in our previous reports. − As shown in Figure , the BINA-based Pt(II) complexes have similar absorption spectra with the same low-energy absorption band at λ abs = 460 nm, even though they bear different O^O auxiliary ligands of acetylacetone (acac), dibenzoylmethane (dbm), and tetramethyl-l,2-dioxetane (tmd). The similar results were observed in the previous work on simple (C^N)Pt(O^O) complexes. , Since the H 8 –BINA-based Pt(II) complexes have a smaller π-conjugation system than BINA-based Pt(II) complexes, H 8 –BINA-based Pt(II) complexes exhibit blue-shifted absorption spectra (λ abs = 445 nm).…”

Section: Resultssupporting

confidence: 77%

“…However, for ( R )-[tmd] , strong face-to-face intermolecular π–π stacking interactions (3.33 Å) are observed between the closest molecules, which might contribute to its low Φ in a powder. The shortest intermolecular Pt–Pt distance is 8.01 Å, , revealing that there is no intermolecular Pt–Pt interactions for ( R )-[tmd] . On the contrary, ( S )-[H 8 -acac] molecules have strong intermolecular Pt–Pt interactions (3.50 Å) but weak face-to-face π–π stacking interactions.…”

Section: Resultsmentioning

confidence: 99%

“…However, all the above Pt(II) complexes are mononuclear Pt(II) complexes. In comparison with mononuclear Pt(II) complexes, multinuclear Pt(II) complexes may have some unique luminescence properties, ,− but they usually might suffer the problem of low solubility and aggregation-caused quenching (ACQ) through intramolecular and/or intermolecular interactions.…”

Section: Introductionmentioning

confidence: 99%

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Axially Chiral Bis-Cycloplatinated Binaphthalenes and Octahydro-Binaphthalenes for Efficient Circularly Polarized Phosphorescence in Solution-Processed Organic Light-Emitting Diodes

Wang

Xiao

et al. 2021

Inorg. Chem.

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A new series of axially chiral binuclear Pt(II) complexes with bridging ligands of binaphthalenes and octahydro-binaphthalenes and auxiliary ligands of β-diketones were designed and prepared. These complexes, identified by spectral and electrochemical methods and single-crystal X-ray diffraction, emit an orange-red phosphorescence with a quantum yield up to 21% and 70% in solution and solid, respectively, due to the effect of steric hindrance from bridging ligands and the 2,3-position extension of chiral axis planes. They can be used as emitters in solution-processed organic light-emitting diodes to achieve luminance efficiency, asymmetry factor, and external quantum efficiency up to 5.4 cd A–1, 3.0 × 10–3, and 3.1%, respectively. Moreover, the essential relationships between their chemical structures and luminescence quantum efficiency and asymmetry factor are discussed, which affords explicit insights for designing circularly polarized luminescent materials and devices.

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Axially Chiral Bis-Cycloplatinated Binaphthalenes and Octahydro-Binaphthalenes for Efficient Circularly Polarized Phosphorescence in Solution-Processed Organic Light-Emitting Diodes

Wang

Xiao

et al. 2021

Inorg. Chem.

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“…All of the complexes displayed intense absorption bands and/or shoulders at 250−350 nm. With reference to previous spectroscopic studies of iridium(III) polypyridine complexes 39 and related salen-bearing transitionmetal complexes, 40 39 In view of limited water solubility of the POSS complexes, a triblock copolymer, Pluronic F-127 (PF127), was employed to make solid dispersions for photophysical measurements in aqueous solution. 41 It is noteworthy that the absorption spectra of complexes 1−3 in water containing 1% PF127 (Figures S1, S4, and S7, respectively) displayed no new features compared to those measured in CH 3 CN and CH 2 Cl 2 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Luminescent Neutral Cyclometalated Iridium(III) Complexes Featuring a Cubic Polyhedral Oligomeric Silsesquioxane for Lipid Droplet Imaging and Photocytotoxic Applications

et al. 2021

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New neutral iridium(III) complexes featuring a cubic polyhedral oligomeric silsesquioxane (POSS) unit, [Ir-(N ∧ C) 2 (L1-POSS)] [HN ∧ C = 2-phenylpyridine (Hppy; 1), 2phenylbenzothioazole (Hbt; 2), and 2-(1-naphthyl)benzothiazole (Hbsn; 3); L1-POSS = (E)-4-[(2-hydroxybenzylidene)amino]benzyl 3-heptakis(isobutyl)POSS-propyl carbamate], were designed and synthesized. Their POSS-free counterparts, [Ir-(N ∧ C) 2 (L1)] [L1 = (E)-N-(4-hydroxymethylphenyl)-1-(2hydroxyphenyl)methanimine; HN ∧ C = Hppy (1a), Hbt (2a), and Hbsn (3a)], and the poly(ethylene glycol) Hbt (2b), and Hbsn (3b)] were also prepared. The photophysical, photochemical, and biological properties of the POSS complexes were compared with those of their POSS-free and PEG-modified counterparts. Upon irradiation, all of these complexes displayed orange-to-red emission and long emission lifetimes under ambient conditions. The bsn complexes 3, 3a, and 3b exhibited the highest singlet oxygen ( 1 O 2 ) generation quantum yields (Φ Δ = 0.85−0.86) in aerated CH 3 CN. Laser-scanning confocal microscopy images revealed that complexes 1−3 and 1a−3a showed exclusive lipid-droplet staining upon cellular uptake, while the PEG derivatives 1b−3b displayed lysosomal localization. Complex 3 was utilized to study various lipid-droplet-related biological events including lipid-droplet accumulation under oleic acid stimulation, the movement of lipid droplets, and preadipocyte differentiation. Notably, 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays indicated that the ppy complexes 1 and 1b and the bt complexes 2 and 2b were noncytotoxic both in the dark and upon irradiation at 450 nm for 5 min (IC 50 > 200 μM), while the bsn complexes 3, 3a, and 3b showed low dark cytotoxicity (IC 50 = 52.9 to >200 μM) and high photocytotoxicity (IC 50 = 1.1−5.3 μM). The cellular uptake, internalization mechanisms, and cell death pathways of these complexes were also investigated. This work not only offers promising luminescent probes for lipid droplets through the structural modification of iridium(III) complexes but also paves the way to the construction of new reagents for theranostics.

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“…Salen ligands were also used for the synthesis of several binuclear Pt(II) complexes such as 3, with CPL response in solid state. [ 19 ] The complexes were prepared as enantiopure or racemic compounds. The auxiliary ppy ligands (ppy = 2‐phenylpyridine) have been shown to impart highly phosphorescent properties Pt(II) complexes.…”

Section: Discussionmentioning

confidence: 99%

Aggregation‐Induced Circularly Polarized Luminescence: Chiral Organic Materials for Emerging Optical Technologies

2020

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physical property differentiating two enantiomers is the direction of rotation of the polarized light. Indeed, the manipulation of polarized light, both in the absorbance and emission mode, is useful in a series of technological applications, such as liquid crystal display (LCD) panels, 3D imaging in biological systems, nonlinear optics, spintronic devices. [5-8] Progresses in the field have been boosted by the increased availability of modern spectroscopic methods. For circular dichroism (CD), which relates to ground-state properties, the commercial availability of the spectrophotometer dates back to the 1960s and has enabled in depth studies of the tertiary structure of proteins. In contrast, circularly polarized luminescence (CPL) spectrophotometers have only been recently commercially available. Nevertheless, CPL gives important additional informations, as it provides information on the excited-state, and luminescence is generally more of interest in terms of materials science and devices. [9] Emissive organic materials have been studied for decades. Among these, organic light-emitting diodes (OLEDs) have reached large-scale commercialization, since they show unique technological advantages with respect to previous technologies: energy-saving, low working voltage, high brightness, and contrast display. Polarized emission and CPL has been the subject of increasing interest. Indeed, circularly polarized OLEDs (CP-OLEDs), based on chiral organic chromophores, have been realized and reported in the recent literature. A variety of chiral organic emitters have been proposed for CPL materials. [10] Aggregation-caused quenching (ACQ) of emission is a common problem that can severely limit the performance of (chiral and achiral) fluorophores in the solid state. The field of emissive dyes has been revolutionized in the early 2000s by Tang's group, which introduced the concept, seemingly counterintuitive at the time, of aggregation-induced emission (AIE). Suitable AIE chromophores (AIEgens) can exhibit strong fluorescence emission in aggregated states, despite being nonemissive in solution. [11] The most frequent mechanism for AIE occurs when AIEgens have freely-rotating groups which, upon excitation, relax back through these rotations instead of releasing energy as light. When they aggregate or crystallize, they become emissive through restricted intramolecular rotation (RIR). Since then, the AIE field literally exploded, and several reports have started to appear on chirality-related CPL emissive dyes. [12] Chirality is becoming increasingly important in the design of organic materials with functional properties, when bulk anisotropy is needed. In the past decades, a plethora of chiral organic materials have been studied and developed. Nanostructures have brought substantial advancement to the realization of organic-molecule-based devices, and the possibilities for solid-state light emission are very promising in view of potential applications. Scientific approaches to the realization of chiral emissive materials are ...

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Syntheses, crystal structures, chirality and aggregation-induced phosphorescence of stacked binuclear platinum(ii) complexes with bridging Salen ligands

Abstract: Chiral Pt(ii) complexes bearing bridging Salen ligands exhibit strong AIP through well-tuned intramolecular Pt–Pt interactions and multiple intermolecular interactions.

Cited by 24 publications

References 74 publications

Axially Chiral Bis-Cycloplatinated Binaphthalenes and Octahydro-Binaphthalenes for Efficient Circularly Polarized Phosphorescence in Solution-Processed Organic Light-Emitting Diodes

Axially Chiral Bis-Cycloplatinated Binaphthalenes and Octahydro-Binaphthalenes for Efficient Circularly Polarized Phosphorescence in Solution-Processed Organic Light-Emitting Diodes

Luminescent Neutral Cyclometalated Iridium(III) Complexes Featuring a Cubic Polyhedral Oligomeric Silsesquioxane for Lipid Droplet Imaging and Photocytotoxic Applications

Aggregation‐Induced Circularly Polarized Luminescence: Chiral Organic Materials for Emerging Optical Technologies

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