- Terpyridine-based heteroditopic ligand for RuIILn3III metallostar architectures (Ln = Gd, Eu, Nd, Yb) with MRI/optical or dual-optical responses
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A new ditopic ligand (L) based on a 2,2′:5′,4″-terpyridine unit substituted in the 2″,6″ positions with iminodiacetate arms has been designed and synthesized for the construction of RuIIL3Ln3III supramolecular architectures. The two components of this system, a 2,2′-bipyridine unit for RuII coordination and a pyridine-bis(iminodiacetate) core for LnIII coordination, are tightly connected via a covalent Carom(py)-Carom(py) bond. The paramagnetic and photophysical properties of the corresponding tetrametallic RuIIL3Gd3III complex have been evaluated, highlighting the potential of this metallostar structure to act as a bimodal MRI/optical imaging agent. Variable-temperature 17O NMR and proton nuclear magnetic relaxation dispersion (NMRD) measurements showed that this complex exhibits (i) a remarkable relaxivity per metallostar molecule, particularly at clinical and high magnetic fields (r1310K = 51.0 and 36.0 mM-1 s-1 at 20 and 300 MHz, respectively) and (ii) a near-optimal residence lifetime of GdIII coordinated water molecule (τM310K = 77.5 ns). This is the result of the presence of two inner-sphere water molecules in the GdIII components of the metallostar and a slow tumbling rate of the molecule (τR310K = 252 ps). Upon excitation in the visible domain (λexc = 472 nm), the RuII component of the complex exhibits a bright-red luminescence centered at 660 nm with a quantum yield of 2.6% in aqueous solutions at pH 7.4. Moreover, this RuIIL3Gd3III assembly is also characterized by a high kinetic inertness in biological media (PBS and human serum solutions) and a high photostability (photobleaching). Finally, preliminary photophysical studies on RuL3Nd3 and RuL3Yb3 assemblies revealed that the RuII center acts as an effective sensitizer for LnIII-based luminescence in the near-IR region. The NdIII species was found to be the most effective at quenching the 3MLCT luminescence of the Ru center.
- Boulay, Alexandre,Deraeve, Cline,Vander Elst, Luce,Leygue, Nadine,Maury, Olivier,Laurent, Sophie,Muller, Robert N.,Mestre-Voegtl, Batrice,Picard, Claude
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- Fabrication of high-performance and low-hysteresis lead halide perovskite solar cells by utilizing a versatile alcohol-soluble bispyridinium salt as an efficient cathode modifier
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A novel alcohol-soluble conjugated bispyridinium salt (FPyBr) is developed and used as a cathode modifier to improve the cathode interface of planar heterojunction perovskite solar cells (PHJ PVSCs). The excellent electron-withdrawing ability of bispyridinium rings endows FPyBr with a favorable energy level alignment with phenyl-C60-butyric acid methyl ester (PCBM) and the cathode (e.g., Al), which leads to an ideal ohmic contact and efficient electron transport and collection. The deep-lying highest occupied molecular orbital energy level of FPyBr can also effectively block hole carriers and thus decrease leakage current and hole-electron recombination at the cathode interface. In addition, FPyBr can n-dope PCBM through an anion-induced electron transfer process, which increases the electron mobility of PCBM drastically, thereby diminishing interfacial resistance and promoting electron transport. As a result, by incorporating an FPyBr cathode interlayer with ethanol solvent, high-performance and low-hysteresis PHJ PVSCs with a maximal power conversion efficiency (PCE) of 19.61% can be realized. In contrast, reference devices without any cathode interlayer display a distinctly worse performance, with a PCE of 16.97%. Therefore, this excellent cathode modifier provides a new opportunity to fabricate high performance multilayer PVSCs using lowerature solution processing without interfacial erosion/mixing.
- Chen, Guiting,Zhang, Fan,Liu, Meiyue,Song, Jun,Lian, Jiarong,Zeng, Pengju,Yip, Hin-Lap,Yang, Wei,Zhang, Bin,Cao, Yong
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- Single-molecule white-light of tris-pyrazolonate-Dy3+ complexes
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Based on the self-assembly of the pyrazolone ligand HPMIP (1-phenyl-3-methyl-4-(isobutyryl)-5-pyrazolone), DyCl3·6H2O and/or the 5-Br-2,2′-bpy (5-bromo-2,2′-bipyridine), two tris-pyrazolonate-Dy3+-complexes [Dy(PMIP)3(H2O)2] (2) and [Dy(PMIP)3(5-Br-2,2′-bpy)] (5) characteristic of dual-emissive emissions toward single-molecule white-light are obtained, respectively, and in dependence on the effective suppression from the oscillator-induced quenching by the involved 5-Br-2,2′-bpy, the color-compensation of the residual ligands-based strong emission and the Dy3+-centered (4F9/2 → 6HJ/2 transitions) multiple emissions renders its Dy3+-complex 5 an efficient (Φem = 4.2%) single-molecule white-light.
- Liu, Jiaxiang,Shi, Qi,He, Yani,Fu, Guorui,Li, Wentao,Miao, Tiezheng,Lü, Xingqiang
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- Copper-Free One-Pot Sonogashira-Type Coupling for the Efficient Preparation of Symmetric Diarylalkyne Ligands for Metal-Organic Cages**
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The often time-consuming and challenging multi-step synthesis of ligands for metal-organic cages is a limiting factor for the discovery and application of new cages. We report a highly efficient copper-free one-pot Sonogashira-type coupling for the preparation of symmetric diarylalkyne ligands on both a small and large scale; bipyridine- and benzimidazole-based ligands for the self-assembly of Co4L6 cages were synthesized in short reaction times and high isolated yields directly from aryl halide precursors. This one-pot method reduces the synthetic burden of ligand synthesis and will facilitate the preparation of ligands with additional functionality for applications of their corresponding cages.
- Lehr, Marc,Paschelke, Tobias,Bendt, Victoria,Petersen, André,Pietsch, Lorenz,Harders, Patrick,McConnell, Anna J.
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- Fullerene receptor based on calix[5]arene through metal-assisted self-assembly
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A self-assembled fullerene receptor based on calix[5]arene has been developed. Silver cation complexation held together the two calix[5]arenes with bipyridine units providing a large enough cavity to take up C60 or C70. The formation of the supramolecular complex with C60 or C70 was established by using the electrospray mass spectrometry.
- Haino, Takeharu,Araki, Hiromi,Yamanaka, Yuko,Fukazawa, Yoshimasa
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- Enhancing Photocatalytic Hydrogen Generation: the Impact of the Peripheral Ligands in Ru/Pd and Ru/Pt Complexes
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The synthesis, photophysical properties and photocatalytic efficiency of a range of novel supramolecular assemblies of the type [Ru(dceb)2(μ-bisbpy)MCl2][PF6]2 and [Ru(bpy)2(μ-bisbpy)MCl2][PF6]2 (M=Pd or Pt, dceb=diethyl 2,2’-bipyridine-4,4’-dicarboxylate, bpy=2,2’-bipyridine and bisbpy=2,2’:5’,3’’:6’’,2’’’-quaterpyridine) are reported. Photocatalytic hydrogen generation was dependent on the nature of the peripheral ligand, on the catalytic centre and on the amount of water present in the photocatalytic mixture. The best catalytic conditions were obtained with the dceb peripheral ligand (turnover numbers up to 513 after 18 h). The experimental data and DFT calculations on both the bpy- and dceb-based compounds indicated that the peripheral dceb ligands participated in the photocatalytic process.
- Das, Nivedita,Bindra, Gurmeet Singh,Paul, Avishek,Vos, Johannes G.,Schulz, Martin,Pryce, Mary T.
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- A Paramagnetic NMR Spectroscopy Toolbox for the Characterisation of Paramagnetic/Spin-Crossover Coordination Complexes and Metal–Organic Cages
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The large paramagnetic shifts and short relaxation times resulting from the presence of a paramagnetic centre complicate NMR data acquisition and interpretation in solution. As a result, NMR analysis of paramagnetic complexes is limited in comparison to diamagnetic compounds and often relies on theoretical models. We report a toolbox of 1D (1H, proton-coupled 13C, selective 1H-decoupling 13C, steady-state NOE) and 2D (COSY, NOESY, HMQC) paramagnetic NMR methods that enables unprecedented structural characterisation and in some cases, provides more structural information than would be observable for a diamagnetic analogue. We demonstrate the toolbox's broad versatility for fields from coordination chemistry and spin-crossover complexes to supramolecular chemistry through the characterisation of CoII and high-spin FeII mononuclear complexes as well as a Co4L6 cage.
- Lehr, Marc,McConnell, Anna J.,N?ther, Christian,Paschelke, Tobias,S?nnichsen, Frank D.,Trumpf, Eicke,Vogt, Anna-Marlene
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- Carboxy derivatised Ir(iii) complexes: synthesis, electrochemistry, photophysical properties and photocatalytic hydrogen generation
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In this contribution the synthesis and characterisation of a series of novel mixed ligand iridium(iii) complexes, functionalised with a carboxy ester or phosphonate groups are reported. These groupings are introduced on the 4-position of either the phenyl pyridine or the 2,2′-bipyridyl ligands. A low temperature high yield synthesis for the precursor [Ir(ppy-COOEt)2(μ-Cl)]2 was developed. The photophysical and electrochemical properties of these compounds are also described, together with their behaviour as photosensitisers for the generation of hydrogen from water.
- Paul, Avishek,Das, Nivedita,Halpin, Yvonne,Vos, Johannes G.,Pryce, Mary T.
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- Electrochemiluminescent dinuclear Ru(II) complexes assembled with 1,1′-(1,2-ethynediyl)- or dimethlyene-bridged bis(bipyridine) ligands: Synthesis and photophysical and electrochemical properties
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1,2-Di(2,2′-bipyridin-5-yl)ethane (BL1) and 1,2-di(2,2′- bipyridin-5-yl)ethyne (BL2) were synthesized as new bridging ligands and coordinated to (RuL2(acetone)2)(PF6) 2 for the preparation of various [Ru(L)2(BL)Ru(L) 2](PF6)4-type dinuclear ruthenium complexes (where BL = BL1, BL2 and L = bpy, o-phen, DTDP). The electrochemical redox potentials, spectroscopic properties, and relative electrochemiluminescence intensity of BL1 and BL2 were characterized and compared to those of well-known tris(1,10-phenanthroline)rutheniun(II) [Ru(o-phen)3](PF 6)2] complex as a reference. Dinuclear Ru(II) complexes containing the conjugated bridging ligand (BL2) showed much more intense electrochemiluminescent responses than dinuclear Ru(II) complexes with the non-conjugated bridging ligand (BL1). Among the complexes with conjugated bridging ligands, [(DTDP)2Ru(bpy-CC-bpy)Ru(DTDP)2](PF 6)4 exhibited enhanced ECL intensities as high as 3.6 times greater than that of the reference, [Ru(o-phen)3](PF 6)2.
- Kim, Minki,Kang, Chang Hoon,Hong, Subong,Lee, Won-Yong,Kim, Byeong Hyo
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- Color-tunable white-light of binary tris-β-diketonate-(Dy3+, Gd3+ x) complexes’ blend under single wavelength excitation
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Based on the Dy3+-centered yellow-light and the ligands-based blue-light of the iso-structural two complexes [Ln(acac)3(5-Br-2,2′-bpy)] (Ln3+ = Dy3+ (2) or Gd3+ (3); Hacac = acetylacetone, 5-Br-2,2′-b
- Shi, Qi,Liu, Jiaxiang,Wang, Jia,Yang, Xiaohui,Zhang, Xingmei,Li, Shuna,Sun, Ping,Chen, Jin,Li, Beibei,Lü, Xingqiang
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- Redox-switchable π-conjugated systems bearing terminal ruthenium(II) complexes
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p-Phenylenediamine bearing terminal bipyridyl moieties was synthesized by palladium-catalyzed amination. The corresponding ruthenium(II) complex was formed and characterized, providing a redox-switchable photoinduced electron-transfer system.
- Shen, Xiuliang,Moriuchi, Toshiyuki,Hirao, Toshikazu
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- Metallosupramolecular Architectures Formed with Ferrocene-Linked Bis-Bidentate Ligands: Synthesis, Structures, and Electrochemical Studies
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The self-assembly of ligands of different geometries with metal ions gives rise to metallosupramolecular architectures of differing structural types. The rotational flexibility of ferrocene allows for conformational diversity, and, as such, self-assembly processes with 1,1′-disubstituted ferrocene ligands could lead to a variety of interesting architectures. Herein, we report a small family of three bis-bidentate 1,1′-disubstituted ferrocene ligands, functionalized with either 2,2′-bipyridine or 2-pyridyl-1,2,3-triazole chelating units. The self-assembly of these ligands with the (usually) four-coordinate, diamagnetic metal ions Cu(I), Ag(I), and Pd(II) was examined using a range of techniques including 1H and DOSY NMR spectroscopies, high-resolution electrospray ionization mass spectrometry, X-ray crystallography, and density functional theory calculations. Additionally, the electrochemical properties of these redox-active metallosupramolecular assemblies were examined using cyclic voltammetry and differential pulse voltammetry. The copper(I) complexes of the 1,1′-disubstituted ferrocene ligands were found to be coordination polymers, while the silver(I) and palladium(II) complexes formed discrete [1 + 1] or [2 + 2] metallomacrocyclic architectures.
- Findlay, James A.,McAdam, C. John,Sutton, Joshua J.,Preston, Dan,Gordon, Keith C.,Crowley, James D.
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- Green light-excitable naphthalenediimide acetylide-containing cyclometalated Ir(iii) complex with long-lived triplet excited states as triplet photosensitizers for triplet-triplet annihilation upconversion
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Naphthalenediimide (NDI) was connected to the ligand of a cyclometalated Ir(iii) complex (Ir-1) via a CC triple bond to enhance the absorption in the visible region and to access long-lived triplet excited states. Ir(ppy) 2(bpy)[PF6] (Ir-2, ppy = 2-phenylpyridine and bpy = 2,2′-bipyridine) was used as a model complex. The photophysical properties of the complexes were studied with steady state and time-resolved spectroscopy. Ir-1 shows strong absorption in the visible region (ε = 11 000 M -1 cm-1 at 542 nm) and in comparison Ir-2 shows typically weak absorption in the visible region (ε -1 cm -1 above 400 nm). Room temperature near IR emission at 732 nm (ΦP = 0.1%) was observed for Ir-1, which is attributed to the NDI localized emissive triplet excited state, by transient absorption spectra and DFT calculations on the spin density surface. The lifetime of the NDI-localized triplet excited state is up to 130.0 μs, which is rarely reported for Ir(iii) complexes. In comparison, Ir-2 shows phosphorescence at 578 nm and the triplet state lifetime is a typical value of 0.3 μs. The complexes were used as triplet photosensitizers for triplet-triplet annihilation (TTA) upconversion and an upconversion quantum yield of 6.7% was observed with Ir-1. No upconversion was observed with Ir-2 as the triplet photosensitizer at the same experimental conditions.
- Ma, Lihua,Guo, Song,Sun, Jifu,Zhang, Caishun,Zhao, Jianzhang,Guo, Huimin
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- A tris-diketonate-Eu(III) complex with the brominated 2,2′-bpy ancillary ligand doped in PMMA for high color-purity red luminescence
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Through the physical doping of a new red-emitting (ΦEuL = 34.9%) tris-β-diketonate Eu3 +-complex [Eu(DBM)3(5-Br-2,2′-bpy)] (1; DBM = dibenzoylmethane) with the brominated 2,2′-bpy ancillary ligand 5-Br-2,2′-bpy (5-bromo-2-(pyridin-2-yl)pyridine) in PMMA (poly(methyl methacrylate), the obtained hybrid material 1@PMMA exhibits significantly improved physical properties including the enhanced Eu3 +-based color-purity red luminescence (ΦEuL = 53.7%).
- He, Yani,Liu, Lin,Zhang, Zhao,Fu, Guorui,Lü, Xingqiang,Wong, Wai-Kwok,Jones, Richard A.
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- Synthesis of Supramolecular Iridium Catalysts and Their Use in Enantioselective Visible-Light-Induced Reactions
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Iridium complexes were prepared which are covalently linked via a bipyridine ligand to a chiral octahydro-1H-4,7-methanoisoindol-1-one skeleton. The skeleton allows for two-point hydrogen bonding to prochiral lactams, which can be processed in iridium-catalyzed photochemical reactions. Attempts to use the iridium complexes in reactions, which typically involve photoinduced electron transfer, failed to provide the desired enantioselectivity. If employed as triplet sensitizers the complexes showed an improved performance and moderate enantioselectivities (up to 29% ee) were achieved in a photochemical epoxide rearrangement.
- B?hm, Alexander,Bach, Thorsten
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- Dynamer and Metallodynamer Interconversion: An Alternative View to Metal Ion Complexation
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A bifunctional molecule containing both a bidentate binding site for metal ions and an aminopyrimidine H-bond donor-acceptor site has been synthesized, and its properties, in its free and coordinated forms, have been established in solution and in the solid state by analytical and spectroscopic methods as well as by X-ray structure determinations. Structural characterization has shown that it forms a one-dimensional H-bonded polymeric assembly in the solid state, while spectroscopic measurements indicate that it also aggregates in solution. The reaction of a simple Fe(II) salt with this assembly results in the emergence of two geometrical isomers of the complex: [FeL3](BF4)2·9H2O - C1 (meridional, mer) and [FeL3]2(SiF6)(BF4)2·12H2O - C2 (facial, fac). While, complex C1 in the solid state generates a one-dimensional H-bonded polymer involving just two ligands on each Fe center, with the chirality of the complex units alternating along the polymer chain, the structure of complex C2 shows NH···N interactions seen in both the ligand and mer complex (C1) structures to be completely absent. Physicochemical properties of the free and complexed ligand differ substantially.
- Brzechwa-Chodzyńska, Anna,Gilski, Miros?aw,Harrowfield, Jack M.,Stefankiewicz, Artur R.,Zieliński, Micha?
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- A Novel Iron(II) Preferring Dopamine Agonist Chelator as Potential Symptomatic and Neuroprotective Therapeutic Agent for Parkinson's Disease
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Parkinson's disease (PD) is a progressive neurodegenerative disorder, and development of disease-modifying treatment is still an unmet medical need. Considering the implication of free iron(II) in PD, we report here the design and characterization of a novel hybrid iron chelator, (-)-12 (D-607) as a multitarget-directed ligand against PD. Binding and functional assays at dopamine D2/D3 receptors indicate potent agonist activity of (-)-12. The molecule displayed an efficient preferential iron(II) chelation properties along with potent in vivo activity in a reserpinized PD animal model. The compound also rescued PC12 cells from toxicity induced by iron delivered intracellularly in a dose-dependent manner. However, Fe3+ selective dopamine agonist 1 and a well-known antiparkinsonian drug pramipexole produced little to no neuroprotection effect under the same experimental condition. These observations strongly suggest that (-)-12 should be a promising multifunctional lead molecule for a viable symptomatic and disease modifying therapy of PD.
- Das, Banibrata,Kandegedara, Ashoka,Xu, Liping,Antonio, Tamara,Stemmler, Timothy,Reith, Maarten E. A.,Dutta, Aloke K.
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- Spontaneous resolution of an electron-deficient tetrahedral Fe4L4 cage
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A highly electron-deficient C3-symmetric tris(bipyridyl) ligand was prepared in four steps and used for the coordination of Fe(OTf)2, thereby resulting in the homochiral assembly of a new family of robust tetrahedral M4L4 cages. This homochiral T-symmetric cage containing a relatively large cavity of 330 ?3 is capable of encapsulating an anionic guest, as was determined by mass spectrometry, 19F NMR spectroscopy, and finally shown from its crystal structure. Moreover, crystallization of the cage from CH3CN led to crystals containing both (ΔΔΔΔ and ΛΛΛΛ) enantiomers, while crystallization from CH3OH resulted in crystals containing only the right-handed (ΔΔΔΔ) cage. The difference in the crystal packing of the two crystal structures is discussed and a feasible explanation for the unique phenomenon among supramolecular cages - spontaneous resolution - is given. Supramolecular chiral resolution: A highly electron-deficient tetrahedral cage was formed from a stable tris(bipyridyl) ligand and a FeII salt. Crystallization of the racemic CH3OH solution leads to spontaneous resolution of the cages, whereas crystallization from CH3CN does not. The encapsulation of an anionic guest was observed in CH3CN.
- Bonakdarzadeh, Pia,Pan, Fangfang,Kalenius, Elina,Jur?ek, Ond?ej,Rissanen, Kari
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- Targeting the estrogen receptor with metal-carbonyl derivatives of estradiol Robert N. Hanson
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As part of our program to develop new probes for the estrogen receptor binding domain, we prepared and evaluated a novel 17α-(rhenium tricarbonyl bipyridyl) vinyl estradiol complex. Preparation of the final compound was achieved using the Stille coupling between the preformed brominated rhenium tricarbonyl bipyridine complex and the tributylstannyl vinyl estradiol. Competitive receptor binding assays and stimulatory assays demonstrated that the final complex retained affinity and efficacy comparable to the corresponding pyridyl vinyl estradiol analog, but lower than that of the phenyl vinyl estradiol analog 2011 Elsevier Ltd. All rights reserved.
- Kirss, Rein,McCaskill, Emmett,Hua, Edward,Tongcharoensirikul, Pakamas,Olmsted, Sandra L.,Labaree, David,Hochberg, Richard B.
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- Synthesis of Nitrile-Functionalized Polydentate N-Heterocycles as Building Blocks for Covalent Triazine Frameworks
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Covalent triazine frameworks (CTFs) based on polydentate ligands are highly promising supports to anchor catalytic metal complexes. The modular nature of CTFs allows to tailor the composition, structure, and function to its specific application. Access to a broad range of chelating building blocks is therefore essential. In this respect, we extended the current available set of CTF building blocks with new nitrile-functionalized N-heterocyclic ligands. This paper presents the synthesis of the six ligands which vary in the extent of the aromatic system and the denticity. The new building blocks may help in a rational design of enhanced support materials in catalysis.
- Debruyne, Maarten,Everaert, Jonas,Heugebaert, Thomas S. A.,Stevens, Christian V.,Van Der Voort, Pascal,Van Hecke, Kristof,Van Speybroeck, Veronique,Vanden Bussche, Flore
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- The kinetics and mechanism of interconversion within a system of [Fe2L 3]4+helicates and [Fe4L 6]8+cages
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Nature builds simple molecules into highly complex assemblies, which are involved in all fundamental processes of life. Some of the most intriguing biological assemblies are those that can be precisely reconfigured to achieve different functions using the same building blocks. Understanding the reconfiguration of synthetic self-assembled systems will allow us to better understand the complexity of proteins and design useful artificial chemical systems. Here we have prepared a relatively simple system in which two distinct self-assembled structures, a [Fe2L3]4+ helicate and a [Fe4L6]8+ cage that are formed from the same precursors, coexist at equilibrium. We have measured the rates of interconversion of these two species and propose a mechanism for the transformation.
- Al-Fayaad, Hydar A.,Arachchige, Kasun S. A.,Brock, Aidan J.,Clegg, Jack K.,Luis, Ena T.,McMurtrie, John C.,Micallef, Aaron S.,Siddique, Rashid G.,Thoburn, John D.
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supporting information
p. 4918 - 4921
(2021/05/26)
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- Luminescence Tunable Europium and Samarium Complexes: Reversible On/Off Switching and White-Light Emission
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Single-molecule functional materials with luminescence tunable by external stimuli are of increasing interest due to their application in sensors, display devices, biomarkers, and switches. Herein, new europium and samarium complexes with ligands having triphenylamine (TPA) groups as the redox center and 2,2′-bipyridine (bpy) as the coordinating groups and diketonate (tta) as the second ligand have been constructed. The complexes show white-light emission in selected solvents for proper mixtures of the emission from Ln3+ ions and the ligands. Meanwhile, they exhibit reversible luminescence switching on/off properties by controlling the external potential owing to intramolecular energy transfer from the Ln3+ ions to the electrochemically generated radical cation of TPA+. Time-dependent density functional theory (TD-DFT) calculations have been performed to study the electronic spectra. The proposed intramolecular energy transfer processes have been verified by density functional theory (DFT) studies.
- Chen, Jing,Xie, Ziyu,Meng, Lingyi,Hu, Ziying,Kuang, Xiaofei,Xie, Yiming,Lu, Can-Zhong
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supporting information
p. 6963 - 6977
(2020/05/18)
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- Cavity-directed nitroaromatics sensing within a carbazole-based luminescent supramolecular M2L3 cage
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The design and preparation of luminescent M2L3 metal-organic cage via the coordination-driven self-assembly of carbazole-based ligand with a V-shaped geometry is described. The cage Zn-L1 with an open cavity which equipped aromatic rich ligands shows the highest emission quenching efficiency towards picric acid than other nitroaromatic explosives. The quenching ability depended on whether there formed the host-guest molecules are well explored by electrospray ionization mass spectrometry (ESI-MS), and isothermal titration microcalorimetry (ITC).
- Feng, Tianchi,Li, Xuezhao,Wu, Jinguo,He, Cheng,Duan, Chunying
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supporting information
(2019/05/29)
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- Isoquinoline compound and its preparation method, the organic electroluminescent device
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The invention provides isoquinoline compounds and a preparation method thereof, and an organic light emitting diode. The isoquinoline compounds are as shown in a molecular formula (I) in the specification. Compared with the prior art, the isoquinoline compounds provided by the invention are prepared by introducing Q1, Q2, Ar1, Ar2, Ar3 and Ar4 groups into benzo[g]isoquinoline compounds, so electronic density and skills can be improved; meanwhile, R1 can improve performances of the isoquinoline compounds, so the organic light emitting diode containing the isoquinoline compounds as shown in the molecular formula (I) has the characteristics of high brightness, good heat resistance, long service life, high efficiency, etc.
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Paragraph 0100; 0101-0105
(2018/03/24)
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- Electron Transfer around a Molecular Corner
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The distance dependence of electron transfer (ET) is commonly investigated in linear rigid rod-like compounds, but studies of molecular wires with integrated corners imposing 90° angles are very rare. By using spirobifluorene as a key bridging element and by substituting it at different positions, two isomeric series of donor-bridge-acceptor compounds with either nearly linear or angled geometries were obtained. Photoinduced ET in both series is dominated by rapid through-bond hole hopping across oligofluorene bridges over distances of up to 70 ?. Despite considerable conformational flexibility, direct through-space and through-solvent ET is negligible even in the angled series. The independence of the ET rate constant on the total number of fluorene units in the angled series is attributed to a rate-limiting tunneling step through the spirobifluorene corner. This finding is relevant for multidimensional ET systems and grids in which individual molecular wires are interlinked at 90° angles.
- Schmidt, Hauke C.,Larsen, Christopher B.,Wenger, Oliver S.
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supporting information
p. 6696 - 6700
(2018/03/26)
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- Exploiting Potential Inversion for Photoinduced Multielectron Transfer and Accumulation of Redox Equivalents in a Molecular Heptad
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Photoinduced multielectron transfer and reversible accumulation of redox equivalents is accomplished in a fully integrated molecular heptad composed of four donors, two photosensitizers, and one acceptor. The second reduction of the dibenzo[1,2]dithiin acceptor occurs more easily than the first by 1.3 V, and this potential inversion facilitates the light-driven formation of a two-electron reduced state with a lifetime of 66 ns in deaerated CH3CN. The quantum yield for formation of this doubly charge-separated photoproduct is 0.5%. In acidic oxygen-free solution, the reduction product is a stable dithiol. Under steady-state photoirradiation, our heptad catalyzes the two-electron reduction of an aliphatic disulfide via thiolate-disulfide interchange. Exploitation of potential inversion for the reversible light-driven accumulation of redox equivalents in artificial systems is unprecedented and the use of such a charge-accumulated state for multielectron photoredox catalysis represents an important proof-of-concept.
- Nomrowski, Julia,Wenger, Oliver S.
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supporting information
p. 5343 - 5346
(2018/05/01)
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- Catalysis of Michael Additions by Covalently Modified G-Quadruplex DNA
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Enantioselective catalysis utilizing G-quadruplex DNA-based artificial metalloenzymes has emerged as a new approach in the field of aqueous-phase homogeneous catalysis. Recently, a catalytic asymmetric Michael addition employing a covalently modified G-quadruplex in combination with CuII ions has been reported. Here we assess, by systematic chemical variation and using various spectrometric techniques, a variety of parameters that govern rate acceleration and stereoselectivity of the reaction, such as the position of modification, the topology of the quadruplex, the nature of the ligand, the length of the linker between ligand and DNA, the chemical identity of monovalent ions and transition metal complexes. The DNA quadruplex modified at position 10 (dU10) with hexynyl-linked bpy ligand showed twice the initial reaction rate as compared with the DNA strand derivatized at position 12 (dU12). The strikingly different dependence of the stereoselectivity on the linker length, and their different spectroscopic properties indicate large differences in the architecture of the catalytic centers between the dU10-derivatized and the dU12-modified quadruplexes. Upon addition of CuII, both types of bpy-derivatized DNA strands form defined 1:1 Cu–DNA complexes stable enough for mass spectrometric analysis, while the underivatized strands exhibit weak and unspecific binding, correlated with much lower catalytic rate acceleration. Both dU10- and dU12-derivatized quadruplexes could be reused ten times without reduction of stereoselectivity.
- Dey, Surjendu,Rühl, Carmen L.,J?schke, Andres
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supporting information
p. 12162 - 12170
(2017/09/14)
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- Noncovalent Interactions in Ir-Catalyzed C-H Activation: L-Shaped Ligand for Para-Selective Borylation of Aromatic Esters
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An efficient strategy for the para-selective borylation of aromatic esters is described. For achieving high para-selectivity, a new catalytic system has been developed modifying the core structure of the bipyridine. It has been proposed that the L-shaped ligand is essential to recognize the functionality of the oxygen atom of the ester carbonyl group via noncovalent interaction, which provides an unprecedented controlling factor for para-selective C-H activation/borylation.
- Hoque, Md Emdadul,Bisht, Ranjana,Haldar, Chabush,Chattopadhyay, Buddhadeb
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p. 7745 - 7748
(2017/06/21)
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- Photoinduced electron transfer in a triarylamine-organoboron-Ru(2,2′-bipyridine)32+ compound
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Long-range electron transfer reactions play a key role in biological photosynthesis, and they are likely to play an important role for future artificial photosynthetic endeavors as well. The possibility to control the rates for long-range electron transfer with external stimuli is of particular interest in this context. In the work presented herein, we explored a donor–bridge–acceptor compound in which intramolecular electron transfer from a triarylamine donor to a photoexcited Ru(bpy)32+ (bpy?=?2,2′-bipyridine) acceptor occurs across an organoboron bridge over a distance of approximately 22??. Fluoride has a high binding affinity to the organoboron bridge in apolar solutions, and the resulting organofluoroborate has a significantly different electronic structure. We explored to what extent the change from an electron-deficient organoboron wire to an electron-rich organofluoroborate bridge affects long-range electron transfer between the distant triarylamine donor and the Ru(bpy)32+ acceptor.
- Heinz, Luisa G.,Wenger, Oliver S.
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p. 230 - 236
(2017/03/07)
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- Dipyridine/phenanthroline onium salt-containing water/alcohol-soluble conjugated micromolecule and preparation method and application thereof
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The invention discloses a dipyridine/phenanthroline onium salt-containing water/alcohol-soluble conjugated micromolecule and its preparation method and an application of the micromolecule used as a cathodic interface modification layer in the upright, inverted and laminated photovoltaic devices. When the dipyridine/phenanthroline onium salt-containing water/alcohol-soluble conjugated micromolecule is used as a cathodic interface modification layer of a photovoltaic cell, interface dipole interaction can be formed between a light absorption active layer and a cathode, the cathode's effects such as effective work function and the like can be reduced, and transmission and extraction of electrons are then promoted. The conjugated micromolecule is soluble in polar solvents such as methanol, N,N-dimethylformamide, dimethyl sulfoxide, water and the like. Thus, intermixing of interface will not happen between an electron transport layer and an active layer when multilayer devices are constructed.
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Paragraph 0053; 0054; 0055
(2017/04/26)
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- Pure white-light and colour-tuning of Eu3+-Gd3+-containing metallopolymer
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Direct white-light (CIE coordinate of x = 0.333, y = 0.335, CCT of 5455 K and CRI of 82) with a high luminous efficiency (18.4%) was achieved in the first example of Eu3+-Gd3+-containing metallopolymer Poly(2-co-NVK-co-4), which also showed tunable purplish-blue to white to yellow-green photoluminescence.
- Zhang, Zhao,He, Ya-Ni,Liu, Lin,Lü, Xing-Qiang,Zhu, Xun-Jin,Wong, Wai-Kwok,Pan, Mei,Su, Cheng-Yong
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p. 3713 - 3716
(2016/03/05)
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- Visible light-harvesting tricarbonyl Re(I) complex: Synthesis and application in intracellular photodynamic effect and luminescence imaging
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Re(I) tricarbonyl rhenium(I) complexes attracted much attention owing to the good cellular uptake ability and rich photophysical properties. However, normally Re(I) complexes show short triplet state lifetime and weak absorption in the visible spectra region, and the absorption wavelength usually is shorter than 450 nm. These features are detrimental to the applications of Re(I) complexes in the areas such as photodynamic therapy (PDT) and luminescence bioimaging. Herein, a novel tricarbonyl rhenium(I) complex Re-1 with strong visible light-absorbing ability (624 nm, ε=5.69×104 L/(mol cm)), long-lived triplet excited state (τ T=448.9 μs) and moderate fluorescence quantum yield (Φ F=41.6%) was prepared. The photophysical properties of Re-1 were studied with steady state UV-Vis absorption and luminescence spectroscopies, nanosecond transient absorption spectroscopy, as well as DFT/TDDFT calculations. Re-1 was used for intracellular PDT and luminescence imaging studies. The results indicate that Re-1 shows low dark toxicity, but it is able to kill cancer cells on illumination with 635 nm LED.
- Zhong, Fangfang,Yuan, Xiaolin,Zhao, Jianzhang,Wang, Quan
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- Tetramethoxybenzene is a good building block for molecular wires: Insights from photoinduced electron transfer
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Two donor bridge-acceptor molecules with terminal triarylamine and Ru(bpy)32+ (bpy = 2,2′-bipyridine) redox partners were synthesized and investigated by cyclic voltammetry, optical absorption, luminescence, and transient absorption spectroscopy. The two dyads differ only by the central bridging unit, which was tetramethoxybenzene (tmb) in one case and unsubstituted phenylene (ph) in the other case. Photoirradiation of the Ru(bpy)32+ complex of the two dyads triggers intramolecular electron transfer from the triarylamine to the 3MLCT-excited metal complex, and this process occurs with time constants of 1.5 and 6.8 ns for the tmb- and ph-bridged dyads, respectively. Thermal electron transfer in the reverse direction then leads to disappearance of the photoproduct with a time constant of 10 ns in both dyads. The faster rate of photoinduced charge transfer in the tmb-bridged dyad can be understood in the framework of a hole-tunneling model in which the electron-rich tmb bridge imposes a more shallow barrier than the less electron-rich ph spacer. Until now tmb-based molecular wires have received very little attention, and alkoxy substituents have been mostly used for improving the solubility of oligo-p-phenylene vinylene (OPV) and oligo-p-phenylene ethynylene (OPE) wires. Our study illustrates how four alkoxy-substituents on a phenylene backbone can have a significant influence on the charge-transfer properties of a molecular wire, and this is relevant in the greater context of a future molecular electronics technology.
- Heinz, Luisa G.,Yushchenko, Oleksandr,Neuburger, Markus,Vauthey, Eric,Wenger, Oliver S.
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p. 5676 - 5684
(2015/06/16)
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- Chemically and electrochemically induced expansion and contraction of a ferrocene rotor
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A 2,2′-bipyridine-appended ferrocene rotor, 1,1′-di(5-yl-ethynyl-2,2′-bipyridine)ferrocene, can be switched from a folded/stacked (syn) conformation to an extended/unstacked (anti) conformation by the addition of [Cu(CH3CN)4](PF6) and 6,6′-dimesityl-2,2′-bipyridine. This extension and contraction process was completely reversible and could be triggered either chemically or electrochemically.
- Scottwell, Syn?ve ?.,Elliott, Anastasia B. S.,Shaffer, Karl J.,Nafady, Ayman,McAdam, C. John,Gordon, Keith C.,Crowley, James D.
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supporting information
p. 8161 - 8164
(2015/05/20)
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- Photoelectric conversion at a [Ru(bpy)3]2+-based metallic triad anchored on ITO surface
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A tri-metallic triad based on a [Ru(bpy)3]2+ moiety connected to Fe(ii) and Co(iii) bisterpyridine has been grafted on an ITO electrode by a stepwise procedure. Under visible light, in the presence of a sacrificial electron donor, the system produces electric current. The photo-current magnitude is compared to the one generated from a Co(iii)-Ru(ii) dyad and shows an increase of 40%.
- Farran, Rajaa,Jouvenot, Damien,Loiseau, Frederique,Chauvin, Jerome,Deronzier, Alain
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supporting information
p. 12156 - 12159
(2014/08/05)
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- Distance dependence of bidirectional concerted proton-electron transfer in phenol-ru(2,2'-bipyridine)32+ dyads
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Proton-coupled electron transfer (PCET) was investigated in three covalent donor-bridge-acceptor molecules with different bridge lengths. Upon photoexcitation of their Ru(bpy)32+ (bpy=2,2,-bipyridine) photosensitizer in acetonitrile, intramolecular long-range electron transfer from a phenolic unit to Ru(bpy)32+ occurs in concert with release of the phenolic proton to pyrrolidine base. The kinetics of this bidirectional concerted proton-electron transfer (CPET) reaction were studied as a function of phenol-Ru(bpy)32+ distance by increasing the number of bridging p-xylene units. A distance decay constant (β) of 0.67±0.23 A-1 was determined. The distance dependence of the rates for CPET is thus not significantly steeper than that for ordinary (i.e., not proton coupled) electron transfer across the same bridges, despite the concerted motion of oppositely charged particles into different directions. Long-range bidirectional CPET is an important reaction in many proteins and plays a key role in photosynthesis; our results are relevant in the context of photoinduced separation of protons and electrons as a means of light-to-chemical energy conversion. This is the first determination of β for a bidirectional CPET reaction. Time for a concert! The dependence of the rates for bidirectional concerted proton-electron transfer (CPET) on the electron donor/electron acceptor distance was determined for the first time (see scheme). The results are relevant in the context of photodriven separation of protons and electrons across natural or artificial membranes as a means of light-to-chemical energy conversion.
- Chen, Jing,Kuss-Petermann, Martin,Wenger, Oliver S.
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supporting information
p. 4098 - 4104
(2014/04/17)
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- COMPOUND CONTAINING SUBSTITUTED TRIPHENYLE RING STRUCTURE, AND ORGANIC ELECTROLUMINESCENT ELEMENT
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An organic compound having an excellent electron injection and transport performance is provided as a material for a low-power-consumption organic electroluminescent device. A low-power-consumption organic electroluminescent device is also provided by using the compound. The compound is a compound of general formula (1) or (2) having a substituted bipyridyl and triphenylene ring structure. The organic electroluminescent device includes a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, and uses the compound as constituent material of at least one of the organic layers.
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Paragraph 0127
(2014/01/17)
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- COMPOUND CONTAINING SUBSTITUTED O-TERPHENYL STRUCTURE, AND ORGANIC ELECTROLUMINESCENT ELEMENT
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A light-emitting-layer host material is provided as material for high-efficiency organic electroluminescent devices. The light-emitting-layer host material has a high excitation triplet level, and is capable of completely confining the triplet excitons of phosphorescent material. A high-efficiency and high-luminance organic electroluminescent device is provided by using the compound. The compound is a compound of general formula (1) having a bipyridyl group and an ortho-terphenyl structure. The organic electroluminescent device includes a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes, and uses the compound as constituent material of at least one of the organic layers.
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Paragraph 0099
(2014/01/17)
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- Visible light-absorbing rhenium(i) tricarbonyl complexes as triplet photosensitizers in photooxidation and triplet-triplet annihilation upconversion
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We prepared N^N Re(i) tricarbonyl chloride complexes (Re-1 and Re-2) that give very strong absorption of visible light. To this end, it is for the first time that boron dipyrimethane (Bodipy) was used to prepare Re(i) tricarbonyl chloride complexes. The π-conjugation linker between the π-conjugation framework of the antenna Bodipy and the Re(i) coordination centre ensures efficient intersystem crossing (ISC). Re-0 without visible light-harvesting ligand was prepared as a model complex in the photophysical studies. Re-1 (with Bodipy) and Re-2 (with carbazole-ethynyl Bodipy) show unprecedented strong absorption of visible light at 536 nm (ε = 91700 M-1 cm -1) and 574 nm (ε = 64600 M-1 cm-1), respectively. Interestingly, different from Re-0, Re-1 and Re-2 show fluorescence of the ligand, not the phosphorescence of the Re(i) coordination centre. However, long-lived triplet excited states were observed upon visible light excitation (τT = 104.0 μs for Re-1; τT = 127.2 μs for Re-2) vs. the short lifetime of Re-0 (τT = 26 ns). With nanosecond time-resolved transient absorption spectroscopy and DFT calculations, we proved that the triplet excited states of Re-1 and Re-2 are localized on the Bodipy ligands. The complexes were used as triplet photosensitizers for two triplet-triplet-energy-transfer (TTET) processes, i.e.1O2 mediated photooxidation and triplet-triplet annihilation (TTA) upconversion. With the strong visible light-harvesting ability, Re-1 proved to be a better 1O2 photosensitizer than the conventional triplet photosensitizer tetraphenylporphyrin (TPP). Significant upconversion was observed with Re-1 as the triplet photosensitizer. Our result is useful for preparation of Re(i) tricarbonyl chloride complexes that show strong absorption of visible light and long-lived triplet excited states and for the application of these complexes as triplet photosensitizers in photocatalysis, photodynamic therapy and TTA upconversion. The Royal Society of Chemistry 2013.
- Yi, Xiuyu,Zhao, Jianzhang,Sun, Jifu,Guo, Song,Zhang, Hongli
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p. 2062 - 2074
(2013/02/26)
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- Hybrid charged heterometallic Pt-Ir complexes: Tailoring excited states by taking the best of both worlds
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The CC-linkage of Pt(PR3)2(CCAr)2 with (CN)2Ir(NN)+ (CN = 2-phenylpyridine; NN = bipyridyl) leads to hetero-bi- and trimetallic species exhibiting photophysical properties reminiscent of both [Pt]- and [Ir]-containing moieties through the generation of a [Pt] → [Ir] charge transfer excited state. The Royal Society of Chemistry 2012.
- Soliman, Ahmed M.,Fortin, Daniel,Harvey, Pierre D.,Zysman-Colman, Eli
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supporting information; experimental part
p. 1120 - 1122
(2012/03/10)
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- One-pot click synthesis of 1N-alkyl-4-aryl-1,2,3-triazoles from protected arylalkynes and alkyl bromides
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1N-Alkyl-4-aryl-1,2,3-triazoles have been prepared through a multicomponent one-pot protocol from the corresponding (arylethynyl)trimethylsilanes and alkyl bromides. In situ alkyl azide formation and alkyne deprotection followed by copper(I)-catalyzed click cycloaddition afforded the desired 1,4-disubstituted 1,2,3-triazoles in generally good to excellent yield, with only minor observation of the undesired 1,5-regioisomeric cycloadduct. The protocol eliminates the need to use reactive organic azides and terminal alkynes. Georg Thieme Verlag Stuttgart. New York.
- Ladouceur, Sebastien,Soliman, Ahmed M.,Zysman-Colman, Eli
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supporting information; experimental part
p. 3604 - 3611
(2011/12/16)
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- One-pot synthesis of 2-bromo-4,5-diazafluoren-9-one via a tandem oxidation-bromination-rearrangement of phenanthroline and its hammer-shaped donor-acceptor organic semiconductors
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An unexpected one-pot tandem procedure of 2-bromo-4,5-diazafluoren-9-one starting from phenanthroline with a yield of up to 50% has been described. The conversion mechanism involves three consecutive oxidation, bromination, and rearrangement reactions. A series of its hammer-shaped donor-acceptor organic semiconductors with solvent-dependent fluorescence have also been constructed via Ullman and/or Friedel-Crafts reaction. Diazafluorenes (DAFs) and derivatives are regarded as promising building blocks or candidates for donor-acceptor organic semiconductors.
- Zhao, Jian-Feng,Chen, Lin,Sun, Peng-Ju,Hou, Xiao-Ya,Zhao, Xiang-Hua,Li, Wei-Jie,Xie, Ling-Hai,Qian, Yan,Shi, Nai-En,Lai, Wen-Yong,Fan, Qu-Li,Huang, Wei
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experimental part
p. 1977 - 1982
(2011/04/22)
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- Metallo-macrocycles with labile coordination sites through self assembly: Binuclear phenyl bridged bisbipyridine manganese complexes
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Self assembly of phenyl bridged bisbipyridines with manganese perchlorate gave structurally different metallo-macrocycles having cis-labile coordination sites which can catalyse olefin epoxidation with peracetic acid in good yield.
- Sham, Kiu-Chor,Zheng, Guoli,Li, Yinyan,Yiu, Shek-Man,Kwong, Hoi-Lun
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supporting information; experimental part
p. 12060 - 12062
(2012/01/14)
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- 2-Pyridyl and 3-pyridylzinc bromides: direct preparation and coupling reaction
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A facile synthetic approach to the direct preparation of 2-pyridyl and 3-pyridylzinc bromides has been demonstrated using Rieke zinc with 2-bromopyridine and 3-bromopyridine, respectively. A variety of different electrophiles have been coupled with the resulting organozinc reagents to give the corresponding cross-coupling products in moderate to good yields.
- Kim, Seung-Hoi,Rieke, Reuben D.
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scheme or table
p. 3135 - 3146
(2010/06/13)
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- Enantiomerically pure C2-symmetric dinuclear silver(I) and copper(I) complexes from a bis(2,2′-bipyridine)-substituted 9,9′-spirobifluorene ligand
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We have prepared a new bis(bipyridyl) ligand 1 based on a chiral 9,9′-spirobifluorene core in both enantiomerically pure forms. This ligand was found to undergo diastereoselective self-assembly to optically pure dinuclear coordination compounds upon coordination to copper(I) and silver(I) ions. Surprisingly, however, the resulting diastereomer was not found to be D2 -symmetric which is usually found for similar bis(bidentate) ligands, but rather C2 -symmetric with differently configurated metal centers.
- Piehler, Torsten,Luetzen, Arne
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scheme or table
p. 329 - 336
(2010/09/06)
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- Persistent metal bis(hexafluoroacetylacetonato) complexes featuring a 2,2′-bipyridine substituted triarylamminium radical cation
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Herein, we describe the preparation of a 2,2′-bipyridine derivative containing a redox-active N,N′-(4,4′-dimethoxydiphenylamino) substituent (1), which readily coordinates M(hfac)2 salts [M = Mn (2), Ni (3), Cu (4)] to generate stable, neutral, and pseudo-octahedral coordination complexes, which have been fully characterized. Cyclic voltammetry and spectroelectrochemical measurements on complexes 2-4 indicate stable one-electron oxidation processes, and the formation of persistent radical cation complexes. The neutral complexes (M = Mn or Ni) were subject to one-electron oxidation with NOPF6 in acetonitrile, and magnetic moments of the resulting solutions were obtained using the Evans method at different temperatures. Our experimental results suggest that the first reported ferromagnetically coupled metal-triarylamminum radical cation complex is obtained when M = Mn2+, and antiferromagnetic coupling results when M = Ni2+. These results are supported by results from density functional theory calculations, which indicate that a π spin polarization mechanism for magnetic exchange coupling is operative in singly oxidized complexes, 2-4.
- Adugna, Sharew,Revunova, Kseniya,Djukic, Brandon,Gorelsky, Serge I.,Jenkins, Hilary A.,Lemaire, Martin T.
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scheme or table
p. 10183 - 10190
(2011/01/05)
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- A facile synthetic route for 2-pyridyl derivatives: direct preparation of a stable 2-pyridylzinc bromide and its copper-free and pd-catalyzed coupling reactions
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Direct preparation of 2-pyridylzinc bromide has been developed. Interestingly, the subsequent coupling reactions with acid chlorides have been carried out without any transition metal catalyst. 2-Pyridylaryl compounds, symmetrical and unsymmetrical 2,2′-b
- Kim, Seung-Hoi,Rieke, Reuben D.
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supporting information; experimental part
p. 5329 - 5331
(2009/12/06)
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- Preparation and properties of thienyl and 2,2'-substituted cobalt-bis(semiquinone) tautomers
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The synthesis and characterization of two new 2,2'-bipyridine ligands containing 3-ethynylthiophene and 3,3'-diethynyl-2,2'-bithiophene substituents is presented, along with the preparation, electronic, and magnetic properties of monoand bimetallic cobalt-semiquinone valence tautomers containing these ligands.
- O'Sullivan, Thomas J.,Djukic, Brandon,Dube, Paul A.,Lemaire, Martin T.
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scheme or table
p. 533 - 538
(2009/10/17)
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- Synthesis and optical properties of bifunctional thiophene molecules coordinated to ruthenium
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(Chemical Equation Presented) A series of unsymmetrical bi- and tetrathiophenes have been synthesized with bipyridine and phosphonic acid functional groups. To do this, phosphonic esters were bonded to thiophenes and the thiophenes coupled to bipyridine. After synthesis of the thienylbipyridines, bis(bipyridine) ruthenium was coordinated to them through the bipyridines. The thienylbipyridines absorb visible light and fluoresce; however, on attachment to ruthenium, both their fluorescence and that of ruthenium are quenched. An additional effect of coordinating ruthenium to the thiophenes is a new absorption band around 470 nm. Variation in oligothiophene length and bipyridine substitution position allowed comparison of the effect of these variables on electronic properties. The longer oligothiophenes display lower-energy absorptions and emissions than that of the shorter thiophenes. In contrast, the position of the bipyridine attachment does not have a large effect on the absorbance or emission wavelength, or on the fluorescence quantum yield.
- Bair, Joseph S.,Harrison, Roger G.
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p. 6653 - 6661
(2008/02/10)
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- Bromination of 2,2'-bipyridile
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A simple and convenient procedure was developed for the synthesis of 5,5'-dibromo-2,2'-bipyridyl providing the target compound in a high yield without the chromatographic separation of the reaction mixture. Polybromo derivatives of 2,2'-bipyridyl were isolated and characterized for the first time. Nauka/Interperiodica 2006.
- Zdravkov,Khimich
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p. 1200 - 1202
(2007/10/03)
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- Bipyridyl- and biphenyl-DNA: A recognition motif based on interstrand aromatic stacking
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The synthesis and incorporation into oligonucleotides of C-nucleosides containing the two aromatic, non-hydrogen-bonding nucleobase substitutes biphenyl (I) and bipyridyl (Y) are described. Their homo- and hetero-recognition properties in different sequential arrangements were then investigated via UV-melting curve analysis, gelmobility assays, CD- and NMR spectroscopy. An NMR analysis of a dodecamer duplex containing one biphenyl pair in the center, as well as CD data on duplexes with multiple insertions provide further evidence for the zipper-like interstrand stacking motif that we proposed earlier based on molecular modeling. UV-thermal melting experiments with duplexes containing one to up to seven I- or Y base pairs revealed a constant increase in Tm in the case of I and a constant decrease for Y. Mixed I/Y base pairs lead to stabilities in between the homoseries. Insertion of alternating I/abasic site- or Y/abasic site pairs strongly decreases the thermal stability of duplexes. Asymmetric distribution of I- or Y residues on either strand of the duplex were also investigated in this context. Duplexes with three natural base pairs at both ends and 50% of I pairs in the center are still readily formed, while duplexes with blunt ended I pairs tend to aggregate unspecifically. Duplexes with one natural overhang at the end of a I-I base pair tract can both aggregate or form ordered duplexes, depending on the nature of the natural bases in the overhang.
- Brotschi, Christine,Mathis, Gerald,Leumann, Christian J.
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p. 1911 - 1923
(2007/10/03)
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