- Synthesis, Photophysics, and Reverse Saturable Absorption of trans-Bis-cyclometalated Iridium(III) Complexes (CNC)Ir(R-tpy)+ (tpy = 2,2′:6′,2″-Terpyridine) with Broadband Excited-State Absorption
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Extending the bandwidth of triplet excited-state absorption in transition-metal complexes is appealing for developing broadband reverse saturable absorbers. Targeting this goal, five bis-terdentate iridium(III) complexes (Ir1-Ir5) bearing trans-bis-cyclometalating (CNC) and 4′-R-2,2′:6′,2″-terpyridine (4′-R-tpy) ligands were synthesized. The effects of the structural variation in cyclometalating ligands and substituents at the tpy ligand on the photophysics of these complexes have been systematically explored using spectroscopic methods (i.e., UV-vis absorption, emission, and transient absorption spectroscopy) and time-dependent density functional theory (TDDFT) calculations. All complexes exhibited intensely structured 1π,π? absorption bands at 1CT)/1π,π? transitions at 400-600 nm. Ligand structural variations exerted a very small effect on the energies of the 1CT/1π,π? transitions; however, they had a significant effect on the molar extinction coefficients of these absorption bands. All complexes emitted featureless deep red phosphorescence in solutions at room temperature and gave broad-band and strong triplet excited-state absorption ranging from the visible to the near-infrared (NIR) spectral regions, with both originating from the 3π,π?/3CT states. Although alteration of the ligand structures influenced the emission energies slightly, these changes significantly affected the emission lifetimes and quantum yields, transient absorption spectral features, and the triplet excited-state quantum yields of the complexes. Except for Ir3, the other four complexes all manifested reverse saturable absorption (RSA) upon nanosecond laser pulse excitation at 532 nm, with the decreasing trend of RSA following Ir2 ≈ Ir4 > Ir1 > Ir5 > Ir3. The RSA trend corresponded well with the strength of the excited-state and ground-state absorption differences (ΔOD) at 532 nm for these complexes.
- Jabed, Mohammed A.,Kilina, Svetlana,Liu, Bingqing,Sun, Wenfang
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- Enhanced singlet oxygen generation of a soft salt through efficient energy transfer between two ionic metal complexes
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In this study, a soft salt complex based photosensitizer has been developed for photodynamic therapy (PDT) of cancer cells. The iridium(iii) complex [Ir(L)(L′)]3+(PF6-)3 (C1) with L and L′ being terpyridine ligands (L = 4′-phenyl-2,2′:6′,2′′-terpyridine, L′ = 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-9-hexyl-9H-carbazole) was chosen as the cationic component, and the iridium(iii) complex [Ir(dfppy)2CN2]-Bu4N+ (A1) was selected as the anionic component. Complexes C1 and A1 are directly connected through electrostatic interaction to form a soft salt based photosensitizer (S1), which exhibited an enhanced singlet oxygen generation rate because of efficient energy transfer between two ionic metal complexes. Furthermore, this novel photosensitizer was successfully applied in photodynamic therapy (PDT) of cancer cells for the first time.
- Ma, Yun,Zhang, Shujun,Wei, Huanjie,Dong, Yafang,Shen, Liang,Liu, Shujuan,Zhao, Qiang,Liu, Li,Wong, Wai-Yeung
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- A Mitochondrion-Localized Two-Photon Photosensitizer Generating Carbon Radicals Against Hypoxic Tumors
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The efficacy of photodynamic therapy is typically reliant on the local concentration and diffusion of oxygen. Due to the hypoxic microenvironment found in solid tumors, oxygen-independent photosensitizers are in great demand for cancer therapy. We herein report an iridium(III) anthraquinone complex as a mitochondrion-localized carbon-radical initiator. Its emission is turned on under hypoxic conditions after reduction by reductase. Furthermore, its two-photon excitation properties (λex=730 nm) are highly desirable for imaging. Upon irradiation, the reduced form of the complex generates carbon radicals, leading to a loss of mitochondrial membrane potential and cell death (IC50light=2.1 μm, IC50dark=58.2 μm, PI=27.7). The efficacy of the complex as a PDT agent was also demonstrated under hypoxic conditions in vivo. To the best of our knowledge, it is the first metal-complex-based theranostic agent which can generate carbon radicals for oxygen-independent two-photon photodynamic therapy.
- Chao, Hui,Chen, Yu,Ji, Liangnian,Kuang, Shi,Liao, Xinxing,Rees, Thomas W.,Sun, Lingli,Zeng, Leli,Zhang, Xianrui,Zhang, Xiting
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supporting information
p. 20697 - 20703
(2020/09/07)
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- Iridium complex with phosphorescent ion pair structure as well as preparation method and application of iridium complex
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The invention discloses an iridium complex with a phosphorescent ion pair structure as well as a preparation method and an application of the iridium complex. The iridium complex is a phosphorescent anion and cation type soft salt iridium complex formed by bonding of a terpyridyl cation complex and a cation complex, wherein the cation complex contains a cyclometalated ligand, and a metal center and cyanogen are taken as auxiliary ligands. The structural general formula of the iridium complex is as shown in the specification. The iridium complex with the phosphorescent ion pair structure is capable of generating singlet oxygen under the radiation of white light, can be applied to the photodynamics treatment field and has very good application prospects in the photodynamics treatment.
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Paragraph 0029; 0032; 0034
(2017/10/31)
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- [Ir(N^N^N)(C^N)L] +: A new family of luminophores combining tunability and enhanced photostability
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The relatively unexplored luminophore architecture [Ir(N^N^N)(C^N)L] + (N^N^N = tridentate polypyridyl ligand, C^N = 2-phenylpyridine derivative, and L = monodentate anionic ligand) offers the stability of tridentate polypyridyl coordination along with the tunability of three independently variable ligands. Here, a new family of these luminophores has been prepared based on the previously reported compound [Ir(tpy)(ppy)Cl] + (tpy = 2,2′:6′,2″-terpyridine and ppy = 2-phenylpyridine). Complexes are obtained as single stereoisomers, and ligand geometry is unambiguously assigned via X-ray crystallography. Electrochemical analysis of the materials reveals facile HOMO modulation through ppy functionalization and alteration of the monodentate ligand's field strength. Emission reflects similar modulation shifting from orange to greenish-blue upon replacement of chloride with cyanide. Many of the new compounds exhibit impressive room temperature phosphorescence with lifetimes near 3 μs and quantum yields reaching 28.6%. Application of the new luminophores as photosensitizers for photocatalytic hydrogen generation reveals that their photostability in coordinating solvent is enhanced as compared to popular [Ir(ppy)2(bpy)]+ (bpy = 2,2′-bipyridine) photosensitizers. Yet, the binding of their monodentate ligand emerges as a source of instability during the redox processes of cyclic voltammetry and mass spectrometry. DFT modeling of electronic structure is provided for all compounds to elucidate experimental properties.
- Chirdon, Danielle N.,Transue, Wesley J.,Kagalwala, Husain N.,Kaur, Aman,Maurer, Andrew B.,Pintauer, Tomislav,Bernhard, Stefan
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p. 1487 - 1499
(2014/03/21)
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