Structural Characterization and Luminescence Properties of a Triphosphine-Stabilized Ag₁₆Cu₉ Heterometallic Alkynyl Cluster

A triphosphine-stabilized Ag₁₆Cu₉ heterometallic alkynyl cluster complex was prepared by the reaction of polymeric silver­(I) (4-<i>tert</i>-butylphenyl)­acetylide with a copper­(I) dpepp (dpepp = bis­(2-(diphenylphosphino)­ethyl)­phenylphosphine) complex and characterized by X-ray crystallography. This Ag₁₆Cu₉ heterometallic alkynyl complex exhibits an unprecedented structural topology stabilized by three auxiliary triphosphine ligands. The (4-<i>tert</i>-butylphenyl)­acetylide exhibits five types of asymmetric bonding modes, including μ-η¹, μ-η¹(σ):η²(π), μ₃-η¹, μ₃-η¹(σ):η¹(σ):η²(π), and η¹-μ₄. This Ag₁₆Cu₉ complex exhibits visible to near-infrared luminescence in both fluid CH₂Cl₂ solution and the solid state

Zn²⁺ Responsive Bimodal Magnetic Resonance Imaging and Fluorescent Imaging Probe Based on a Gadolinium(III) Complex

A Zn²⁺-responsive bimodal magnetic resonance imaging (MRI) and luminescence imaging probe GdL was synthesized. The relaxivity and luminescence properties were examined. In the presence of 0.5 equiv of Zn²⁺, the longitudinal relaxivity is increased from 3.8 mM^–1 s^–1 to 5.9 mM^–1 s^–1 at 23 MHz and 25 °C with 55% enhancement, whereas the fluorescence exhibits a 7-fold increase. The Zn²⁺ responsive imaging probe shows favorable selectivity and tolerance over a variety of biologically relevant anions and metal ions in physiological pH range for both relaxivity and luminescence. In vitro phantom images and confocal fluorescence images in living cells show that the bimodal Zn²⁺ probe can effectively enhance <i>T</i>₁-weighted imaging contrast and luminescence imaging effect through Zn²⁺ coordination with excellent cellmembrane permeability and biocompatibility. Spectral and electrospray ionization mass spectrometry (ESI-MS) studies indicate that two different Zn²⁺-bound species, (GdL)₂Zn and GdLZn, are formed when 0.5 and 1 equiv of Zn²⁺ are bound to GdL complex, respectively. Crystal structural determination and dysprosium-induced ¹⁷O NMR shift (DIS) experiment demonstrate that the increased molecular weight and the improved molecular rigidity upon complexation of Zn²⁺ with GdL is the primary factor for relaxivity enhancement. Significant enhancement of the luminescence is due to a heavy atom effect and much increased molecular rigidity upon Zn²⁺ binding to 8-sulfonamidoquinoline chromophore

Structural and Photophysical Studies on Geometric (Er₂Yb₂/Yb₂Er₂) and Configurational (EuTb₃/Eu₃Tb) Isomers of Heterotetranuclear Lanthanide(III) Complexes

Heterotetranuclear geometrical (Er₂Yb₂/Yb₂Er₂) and configuational (EuTb₃/Eu₃Tb) isomeric lanthanide­(III) complexes have been synthesized and characterized by spectroscopy as well as X-ray crystallography. The geometric Er₂Yb₂/Yb₂Er₂ isomers exhibit dual emissions from both erbium­(III) and ytterbium­(III) ions. For the EuTb₃/Eu₃Tb configurational isomers, the Tb^III subunits transfer energy to the Eu^III centers in the EuTb₃ complex, whereas the Tb^III ion in the TbEu₃ complex serves mainly as a structural stabilizer

Vapochromic and Mechanochromic Phosphorescence Materials Based on a Platinum(II) Complex with 4-Trifluoromethylphenylacetylide

Planar platinum­(II) complex Pt­(Me₃SiCCbpyCCSiMe₃)­(CCC₆H₄CF₃-4)₂ (<b>6</b>) with 5,5′-bis­(trimethylsilylethynyl)-2,2′-bipyridine and 4-trifluoromethylphenylacetylide exhibits remarkable luminescence vapochromic and mechanochromic properties and a thermo-triggered luminescence change. Solid-state <b>6</b> is selectively sensitive to vapors of oxygen-containing volatile compounds such as tetrahydrofuran (THF), dioxane, and tetrahydropyrane (THP) with phosphorescence vapochromic response red shifts from 561 and 608 nm to 698 nm (THF), 689 nm (dioxane), and 715 nm (THP), respectively. Upon being mechanically ground, desolvated <b>6</b>, <b>6</b>·CH₂Cl₂, and <b>6</b>·¹/₂CH₂ClCH₂Cl exhibit significant mechanoluminescence red shifts from 561 and 608 nm to 730 nm, while vapochromic crystalline species <b>6</b>·THF, <b>6</b>·dioxane, or <b>6</b>·THP affords a mechanoluminescence blue shift from 698 nm (THF), 689 nm (dioxane), or 715 nm (THP) to 645 nm, respectively. When the compounds are heated, a thermo-triggered luminescence change occurs, in which bright yellow luminescence at 561 and 608 nm turns to red luminescence at 667 nm with a drastic red shift. The multi-stimulus-responsive luminescence switches have been monitored by the changes in emission spectra and X-ray diffraction patterns. Both X-ray crystallographic and density functional theory studies suggest that the variation in the intermolecular Pt–Pt interaction is the key factor in inducing an intriguing luminescence switch

Zn²⁺ Responsive Bimodal Magnetic Resonance Imaging and Fluorescent Imaging Probe Based on a Gadolinium(III) Complex

A Zn²⁺-responsive bimodal magnetic resonance imaging (MRI) and luminescence imaging probe GdL was synthesized. The relaxivity and luminescence properties were examined. In the presence of 0.5 equiv of Zn²⁺, the longitudinal relaxivity is increased from 3.8 mM^–1 s^–1 to 5.9 mM^–1 s^–1 at 23 MHz and 25 °C with 55% enhancement, whereas the fluorescence exhibits a 7-fold increase. The Zn²⁺ responsive imaging probe shows favorable selectivity and tolerance over a variety of biologically relevant anions and metal ions in physiological pH range for both relaxivity and luminescence. In vitro phantom images and confocal fluorescence images in living cells show that the bimodal Zn²⁺ probe can effectively enhance <i>T</i>₁-weighted imaging contrast and luminescence imaging effect through Zn²⁺ coordination with excellent cellmembrane permeability and biocompatibility. Spectral and electrospray ionization mass spectrometry (ESI-MS) studies indicate that two different Zn²⁺-bound species, (GdL)₂Zn and GdLZn, are formed when 0.5 and 1 equiv of Zn²⁺ are bound to GdL complex, respectively. Crystal structural determination and dysprosium-induced ¹⁷O NMR shift (DIS) experiment demonstrate that the increased molecular weight and the improved molecular rigidity upon complexation of Zn²⁺ with GdL is the primary factor for relaxivity enhancement. Significant enhancement of the luminescence is due to a heavy atom effect and much increased molecular rigidity upon Zn²⁺ binding to 8-sulfonamidoquinoline chromophore

Spectroscopic and Phosphorescent Modulation in Triphosphine-Supported PtAg₂ Heterotrinuclear Alkynyl Complexes

A series of highly phosphorescent PtAg₂ heterotrinuclear alkynyl complexes with bis­(diphenylphosphinomethyl)­phenylphosphine (dpmp) were prepared and characterized structurally. The solution phosphorescence with various emitting colors is systematically modulated by modifying substituents as well as π-conjugated systems in aromatic acetylides. The crystals, powders, or films exhibit reversible stimuli-responsive phosphorescence changes upon exposure to vapor of MeCN, pyridine, DMF, etc., resulting from perturbation of d⁸-d¹⁰ metallophilic interaction in the excited states as a consequence of the formation/disruption of Ag–solvent bonds. Both experimental and time-dependent density functional theory (TD-DFT) studies demonstrate that d⁸-d¹⁰ metallophilic interaction exerts a crucial role on phosphorescent characteristics due to the PtAg₂ cluster-based ³[d → p] state. This study affords a paradigm for phosphorescence modulation in d⁸–d¹⁰ heteronuclear complexes

Structures and Phosphorescence Properties of Triphosphine-Supported Au₂Ag₂ and Au₈Ag₄ Alkynyl Cluster Complexes

The synthesis, structure, and phosphorescence properties of two families of triphosphine-supported Au­(I)–Ag­(I) heteronuclear alkynyl cluster complexes with unprecedented Au₂Ag₂ and Au₈Ag₄ cluster structures are described. The phosphorescence emission over the whole visible light region was systematically tuned through modification of the electronic effects in aromatic acetylide ligands to attain bright phosphorescence with different luminescent colors. Introduction of electron-withdrawing CF₃ to phenylacetylides results in the emission spectral blue-shift, while it shows progressive red-shift upon introducing electron-donating Bu^t, OMe, or NMe₂. As demonstrated from both experimental and theoretical studies, the phosphorescence arises primarily from ³LLCT/³IL and Au₂Ag₂/Au₈Ag₄ cluster-centered ³[d→p] transitions

Metal Complexes with a Hexadentate Macrocyclic Diamine-Tetracarbene Ligand

A hexadentate macrocyclic N-heterocyclic carbene (NHC) ligand precursor (H₄L)­(PF₆)₄ containing four benzimidazolium and two secondary amine groups, has been synthesized and characterized. Coordination chemistry of this new macrocyclic diamine-tetracarbene ligand has been studied by the synthesis of its Ag­(I), Au­(I), Ni­(II), and Pd­(II) complexes. Reactions of (H₄L)­(PF₆)₄ with different equiv of Ag₂O result in Ag­(I) complexes [Ag­(H₂L)]­(PF₆)₃ (<b>1</b>) and [Ag₂(H₂L)]­(PF₆)₄ (<b>2</b>). A mononuclear Au­(I) complex [Au­(H₂L)]­(PF₆)₃ (<b>3</b>) and a trinuclear Au­(I) complex [Au₃(H₂L)­(Cl)₂]­(PF₆) (<b>4</b>) are obtained by transmetalation of <b>1</b> and <b>2</b> with AuCl­(SMe₂), respectively. Reactions of (H₄L)­(PF₆)₄ with Ni­(OAc)₂ and Pd­(OAc)₂ in the presence of NaOAc yield [Ni­(L)]­(PF₆)₂ (<b>5</b>) and [Pd­(L)]­(PF₆)₂ (<b>6</b>), respectively, containing one Ni­(II) and Pd­(II) ion with distorted square-planar geometry. Using more NaOAc results in the formation of unusual dinuclear complexes [Ni₂(L–2H)]­(PF₆)₂ (<b>7</b>) and [Pd₂(L–2H)]­(PF₆)₂ (<b>8</b>) (L–2H = deprotonated ligand after removing two H⁺ ions from two secondary amine groups in L), respectively, featuring a rare M₂N₂ core formed by two bridging amides. <b>7</b> is also formed by the reaction of <b>5</b> with 1.0 equiv of Ni­(OAc)₂·4H₂O in the presence of NaOAc. Transmetalation of <b>2</b> with 2.0 equiv of Ni­(PPh₃)₂Cl₂ gives [Ni₂(L)­(μ-O)]­(PF₆)₂ (<b>9</b>), the first example of a dinuclear Ni­(II) complex with a singly bridging oxo group. <b>9</b> is converted to <b>7</b> in good yield through the treatment with NaOAc

Phosphorescent PtAu₂ Complexes with Differently Positioned Carbazole–Acetylide Ligands for Solution-Processed Organic Light-Emitting Diodes with External Quantum Efficiencies of over 20%

The utilization of phosphorescent metal cluster complexes as new types of emitting materials in organic light-emitting diodes (OLEDs) is becoming an alternative and viable approach for achieving high-efficiency electroluminescence. We report herein the design of cationic PtAu₂ cluster complexes with differently positioned 9-phenylcarbazole–acetylides to serve as phosphorescent emitters in OLEDs. The rigid structures of PtAu₂ complexes cause intense phosphorescence with quantum yields of over 85%, which originates from ³[π­(phenylcarbazole–acetylide) → π*­(dpmp)] ligand-to-ligand and ³[π­(phenylcarbazole–acetylide) → p/s­(PtAu₂)] ligand-to-metal charge-transfer triplet excited states. When 8 wt % PtAu₂ is doped to blended host materials of TCTA and OXD-7 (2:1 weight ratio) as light-emitting layers, solution-processed OLEDs give a current efficiency of 78.2 cd A^–1 and an external quantum efficiency (EQE) of 21.5% at a practical luminance of 1029 cd m^–2 with a slow efficiency roll-off upon increasing luminance. This represents the best device performance and the highest efficiency recorded at practical luminance for solution-processed OLEDs

<i>RBMS3</i> arrests cell cycle at the G1/S checkpoint.

<p>(<b>A</b>) Representative and summary of DNA content detected by flow cytometry showed that the percentage of cells in the S phase was lower while the percentage of cells in the G1 phase was higher in SUNE1-RBMS3 cells than that in SUNE1-V1 cells. (* p<0.05, Student’s <i>t</i>-test). Values were expressed as mean ± SD of three independent experiments. (<b>B</b>) Protein expressions of cyclin D1, cyclin E, CDK2, p53, p21, Rb and Rb (Ser780) were compared between <i>RBMS3</i>- and empty vector-transfected NPC cells. β-actin was used as a loading control.</p