High-efficiency orange and yellow organic light-emitting devices using platinum(II) complexes containing extended π -conjugated cyclometalated ligands as dopant materials

Two luminescent platinum(II) complexes 1 and 2 containing extended π -conjugated cyclometalated ligands have been used as dopant materials for the construction of two high-efficiency organic light-emitting devices I and II. Device I (containing dopant 1) emits orange emission and exhibits a maximum external quantum efficiency of 12.4%, a maximum luminous efficiency of 32.3 cdA, and a maximum power efficiency of 11.2 lmW. Device II (containing dopant 2) emits yellow light and exhibits a maximum external quantum efficiency of 16.1%, a maximum luminous efficiency of 51.8 cdA, and a maximum power efficiency of 23.2 lmW. © 2007 American Institute of Physics.published_or_final_versio

Chromo- and Fluorogenic Organometallic Sensors

Compounds that change their absorption and/or emission properties in the presence of a target ion or molecule have been studied for many years as the basis for optical sensing. Within this group of compounds, a variety of organometallic complexes have been proposed for the detection of a wide range of analytes such as cations (including H+), anions, gases (e.g. O 2, SO2, organic vapours), small organic molecules, and large biomolecules (e.g. proteins, DNA). This chapter focuses on work reported within the last few years in the area of organometallic sensors. Some of the most extensively studied systems incorporate metal moieties with intense long-lived metal-to-ligand charge transfer (MLCT) excited states as the reporter or indicator unit, such as fac-tricarbonyl Re(I) complexes, cyclometallated Ir(III) species, and diimine Ru(II) or Os(II) derivatives. Other commonly used organometallic sensors are based on Pt-alkynyls and ferrocene fragments. To these reporters, an appropriate recognition or analyte-binding unit is usually attached so that a detectable modification on the colour and/or the emission of the complex occurs upon binding of the analyte. Examples of recognition sites include macrocycles for the binding of cations, H-bonding units selective to specific anions, and DNA intercalating fragments. A different approach is used for the detection of some gases or vapours, where the sensor's response is associated with changes in the crystal packing of the complex on absorption of the gas, or to direct coordination of the analyte to the metal centre

Observation of intramolecular C-H⋯F-C contacts in non-metallocene polyolefin catalysts: Model for weak attractive interactions between polymer chain and noninnocent ligand

Attracting attention! The existence of attractive interactions between a functionalized ancillary ligand and a growing alkyl chain is a highly novel concept in olefin polymerization reactions (see scheme). Such interactions must be very weak so that the chain-propagation process is not perturbed, and "controversial" hydrogen bonds with strong dispersive character, such as CH⋯FC, are therefore ideal in this role (see scheme).link_to_subscribed_fulltex

Cerium(III) and neodymium(III) amides derived from a chelating 2-pyridyl amido ligand

Homoleptic Ce(III) and Nd(III) triamides [LnL3] [Ln = Ce (1) or Nd (2)] and the heterobimetallic amide-alkoxide derivatives [LnL2(ΜOBut)2M(tmeda)] [Ln = Ce, M = Na (3); Ln = Nd, M = Na (4); Ln = Nd, M = K (5)] supported by the bulky [N(SiButMe2)(2-C5H3 N-6-Me)]- ligand (L-) have been successfully synthesized and characterized. Complexes 1-3 and 5 show a high activity toward the ring-opening polymerization of ε-caprolactone.link_to_subscribed_fulltex

Structures, photoluminescence, and reversible vapoluminescence properties of neutral platinum(II) complexes containing extended π-conjugated cyclometalated ligands

Reacting K2PtCl4 with the tridentate R-C^N^C-H 2 ligands 2,6-di-(2′-naphthyl)-4-R-pyridine (R = H, 1a; Ph, 1b; 4-BrC6H4, 1c; 3,5-F2C6H 3, 1d) in glacial acetic acid, followed by heating in dimethyl sulfoxide (DMSO), gave complexes [(R-C^N^C)Pt(DMSO)] (2a-d). In the crystal structures of 2a-c, the molecules are paired in a head-to-tail orientation with Pt⋯Pt separations >6.3 Å, and there are extensive close C-H⋯π (d = 2.656-2.891 Å), π⋯π (d = 3.322-3.399 Å), and C-H⋯O=S (d = 2.265-2.643 Å) contacts. [(Ph-C^N^C)Pt(PPh3)] (3) was prepared by reacting 2b with PPh 3. Reactions of 2a-d with bis(diphenylphosphino)-methane (dppm) gave [(R-C^N^C)2Pt2(μ-dppm)] (4a-d). Both head-to-head (syn) and head-to-tail (anti) conformations were found for 4a·6CHCl 3·C5H12, whereas only one conformation was observed for 4b· 2CHCl3 (syn), 4c·3CH 2Cl2 (syn), and 4d·2CHCl3 (anti). In the crystal structures of 4a-d, there are close intramolecular Pt⋯Pt contacts of 3.272-3.441 Å in the syn conformers, and long intramolecular Pt⋯Pt separations of 5.681-5.714 Å in the anti conformers. There are weak C-H⋯X (d = 2.497-3.134 Å) and X⋯X (X = Cl or Br; d = 2.973-3.655 Å) interactions between molecules 4a-d and occluded CHCl3/CH2Cl2 molecules, and their solvent channels are of varying diameters (∼9-28 Å). Complexes 2a-d, 3, and 4a-d are photoluminescent in the solid state, with emission maxima at 602-643 nm. Upon exposure to volatile organic compounds, 4a shows a fast and reversible vapoluminescent response, which is most intense with volatile halogenated solvents (except CCl4). Powder X-ray diffraction analysis of desolvated 4a revealed a more condensed molecular packing of syn and anti complexes than crystal 4a·6CHCl3· C5H 12. © 2006 American Chemical Society.link_to_subscribed_fulltex

Anticancer gold(I)-phosphine complexes as potent autophagy-inducing agents

A panel of anticancer gold(I)-phosphine complexes exhibit significant autophagy-inducing properties in cancer cells. © 2011 The Royal Society of Chemistry.link_to_subscribed_fulltex

The 3[ndσ*(n+1)pσ] emissions of linear silver(I) and gold(I) chains with bridging phosphine ligands

The complexes [Au3(dcmp)2] [X]3 (dcmp = bis(dicyclohexylphosphinomethyl)cyclohexylphosphine; X = Cl- (1), ClO4 - (2), OTf- (3), PF6 - (4), SCN-(5)}, [Ag3(dcmp)2] [ClO 4]3 (6), and [Ag3(dcmp)2Cl 2][ClO4] (7) were prepared and their structures were determined by X-ray crystallography. Complexes 2-4 display a high-energy emission band with λmax at 442-452 nm, whereas 1 and 5 display a low-energy emission with λmax at 558-634 nm in both solid state and in dichloromethane at 298 K. The former is assigned to the 3[5dσ*6pσ] excited state of [Au3-(dcmp) 2]3+, whereas the latter is attributed to an exciplex formed between the 3[5dσ*6pσ] excited state of [Au3-(dcmp)2]3+ and the counterions. In solid state, complex [Ag3(dcmp)2]-[ClO4]3 (6) displays an intense emission band at 375 nm with a Stokes shift of ≈7200 cm-1 from the 1[4dσ*-→5pσ] absorption band at 295 nm. The 375 nm emission band is assigned to the emission directly from the 3[4dσ*5pσ] excited state of 6. Density functional theory (DFT) calculations revealed that the absorption and emission energies are inversely proportional to the number of metal ions (n) in polynuclear AuI and AgI linear chain complexes without close metal⋯anion contacts. The emission energies are extrapolated to be 715 and 446 nm for the infinite linear AuI and AgI chains, respectively, at metal⋯metal distances of about 2.93-3.02 Å. A QM/MM calculation on the model [Au3(dcmp)2Cl 2]+ system, with Au⋯Cl contacts of 2.90-3.10 Å, gave optimized Au⋯Au distances of 2.99-3.11 Å in its lowest triplet excited state and the emission energies were calculated to be at approximately 600-690 nm, which are assigned to a three-coordinate Au I site with its spectroscopic properties affected by Au I⋯AuI interactions. © 2009 Wiley-VCH Verlag GmbH & Cu. KGaA.link_to_subscribed_fulltex

Luminescent gold(I) and copper(I) phosphane complexes containing the 4-nitrophenylthiolate ligand: Observation of π→π* charge-transfer emission

Gold(I) and copper(I) phosphane complexes containing the 4-nitrophenylthiolate ligand, namely [(PCy3)Au(SC6H 4NO2-4)] (1) (PCy3 = tricyclohexylphosphane), [Au2(μ-dcpm)-(SC6H4NO2-4) 2] (2) [dcpm = bis(dicyclohexylphosphanyl)-methane], [Au 2(μ-dppm)(SC6H4NO2-4) 2] (3) [dppm = bis(diphenylphosphanyl) methane], and [(μ2-SC6H4NO2-4) 2(μ3-SC6H4NO2-4) 2(CuPPh3)4] (4), were prepared and characterized by X-ray crystal analysis. All of these complexes show an intense absorption band with λmax at 396-409 nm attributed to the intraligand (IL) π(S)→π*(C6H4NO 2-4) charge-transfer transition. The assignment is supported by the results of DFT and TDDFT calculations on the model complexes [PH 3Au(SC6H4NO2-4)] and [(μ2-SC6H4NO2-4) 2(μ3-SC6H4NO2-4) 2(CuPH3)4]. The emissions of solid samples and glassy solutions (methanol/ethanol, 1:4, v/v) of 1-4 at 77 K are assigned to the [π(S)→π*(C6H4NO2-4)] charge-transfer excited state. Metallophilic interactions are not observed in both solid state and solutions of complexes 1-3. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.link_to_subscribed_fulltex

Anticancer cyclometalated [AuIIIm(C∧N∧C)mL]n+ compounds: Synthesis and cytotoxic properties

A series of cyclometalated gold(III) compounds [Aum-(C ∧N∧C)mL]n+ (m = 1-3; n=0-3: HC∧N∧CH=2,6-diphenylpyridine) was prepared by ligand substitution reaction of L with N-donor or phosphine ligands. The [Aum(C∧N∧C)mL]n+ compounds are stable in solution in the presence of glutathione. Crystal structures of the gold(in) compounds containing bridging bi- and tridentate phosphino ligands reveal the presence of weak intramolecular JI-JT stacking between the [Au(C∧N∧C)]+ units. Results of MTT assays demonstrated that the [Aum(C∧N ∧C)mL]n+ compounds containing nontoxic N-donor auxiliary ligands (2) exert anticancer potency comparable to that of cisplatin, with IC50 values ranging from 1.5 to 84 μM. The use of [Au(C∧N∧C)(1-methylimidazole)]+ (2a) as a model compound revealed that the gold(III)-induced cytotoxicity occurs through an apoptotic cell-death pathway. The cell-free interaction of 2 a with double-stranded DNA was also examined. Absorption titration showed that 2 a binds to calfthymus DNA (ctDNA) with a binding constant of 4.5 × 10 5 dm3 mol-1 at 298 K. Evidence from gel-mobility-shift assays and viscosity measurements supports an intercalating binding mode for the 2a-DNA interaction. Cell-cycle analysis revealed that 2 a causes S-phase cell arrest after incubation for 24 and 48 hours. The cytotoxicity of 3b-g toward cancer cells (IC50-0.04-4.3 μM) correlates to that of the metal-free phosphine ligands (IC50=0.1-38.0 μM), with [Au2(C∧N∧C) 2(μ-dppp)]2+ (3d) and dppp (dppp = 1,2- bis(diphenylphosphino)propane) being the most cytotoxic gold(III) and metal-free compounds, respectively. Compound 3d shows a cytotoxicity at least ten-fold higher than the other gold(III) analogues; in vitro cellular-uptake experiments reveal similar absorptions for all the gold(III) compounds into nasopharyngeal carcinoma cells (SUNE1) (1.18-3.81 ng/cell; c.f., 3d = 2.04ng/cell), suggesting the presence of non-gold-mediated cytotoxicity. Unlike 2 a, both gold(III) compounds [Au(C∧N∧C)(PPh3)]- (3a) (PPh3 = triphenylphosphine) and [Au2(C ∧N∧C)2(μ-dpPP)]2+ (3d) interact only weakly with ctDNA and do not arrest the cell cycle. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.link_to_subscribed_fulltex

Quinoneimido complexes of a metalloporphyrin: Isolation, X-ray crystal structures, and DFT calculations

Terminal quinoneimido complexes [RuIV (por) (NQu)(X)] (X=OEt: 1, OH: 2) were formed from the reaction of [Ru VI(por)O2] with 2,6-dimethylaniline. The X-ray crystal structures of 1 feature Ru-N(quinoneimido) bond lengths of 1.787(7)-1.80(2). Reaction of 2 with N-phenyl-benzene-1,4-diamine afforded bis(quinoneimido) complex [Ru(por) (NQu) (NQu')]. DFT calculations on 3 and 4 revealed a significant effect of 'Ru doping' on the oligoaniline structure. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.link_to_subscribed_fulltex