- A Dual-Responsive Bola-Type Supra-Amphiphile Constructed from a Water-Soluble Calix[4]pyrrole and a Tetraphenylethene-Containing Pyridine Bis-N-oxide
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Complexation between a water-soluble calix[4]pyrrole and a ditopic pyridine N-oxide derivative in aqueous media produces a bola-Type supra-Amphiphile that self-Assembles to produce higher order morphologies, including multilamellar vesicles and micelles d
- Chi, Xiaodong,Zhang, Huacheng,Vargas-Zúniga, Gabriela I.,Peters, Gretchen M.,Sessler, Jonathan L.
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- Lead(II) 4,4′-Bipyridine N-Oxide Coordination Polymers – Highly Phosphorescent Materials with Mechanochromic Luminescence Properties
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In the PbIIX2/bp4mo (4,4′-bipyridine N-oxide) system, four coordination polymers (CPs) with the formulation of [PbX2(bp4mo)] are obtained. Compounds 1 and 2, in which X = Cl and Br, are polymorphs whose acentric structures are based on 2D CPs. On the contrary, the compound 3 (X = I) shows a close, but centrosymmetrical, structure compared with the ones of 1 and 2. Finally, the structure of compound 4, in which X = NO3–, is described by two-interpenetrated 3D networks. They all exhibit phosphorescence properties characterized by a broad emission band at around 600 nm, with lifetimes longer than tens of μs and quite high quantum yields that increase in the halide series from 6 % (1) to 27 % (3) and up to 34 % for 4. They also exhibit mechanochromic luminescence (MCL) properties: the grinding (g) of samples 1–4 involves nearly complete extinction of the luminescence, as well as a crystal to amorphous transition of the corresponding samples 1-g to 4-g. This phenomenon, which can be also considered a crystallization-enhanced emission process, is reversible either by heating, exposure to vapour (H2O, acetone) or by recrystallization in a few drops of acetone; however, it is accompanied by a loss of emission intensity. These compounds represent the first examples of MCL materials based on Pb2+.
- Toma, Oksana,Mercier, Nicolas,Allain, Magali,Meinardi, Francesco,Botta, Chiara
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- Dimensionality Alteration and Intra- versus Inter-SBU Void Encapsulation in Zinc Phosphate Frameworks
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4,4′-Bipyridine-N-oxide (BIPYMO, 1), a less commonly employed coordination polymer linker, has been used as a ditopic spacer to bridge double-four-ring (D4R) zinc phosphate clusters to form novel framework coordination polymers. Zinc phosphate framework compounds [Zn4(X-dipp)4(BIPYMO)2]n·2MeOH [X = H (2), Cl (3), Br (4), I (5); dipp = 2,6-diisopropylphenyl phosphate] have been obtained by treating a methanol solution of zinc acetate with X-dippH2 and BIPYMO (in a 1:1:1 molar ratio) at ambient conditions. Framework phosphates 2-5 can also be obtained by treating the preformed D4R cubanes [Zn(X-dipp)(DMSO)]4 with required quantities of BIPYMO in methanol. Single-crystal X-ray diffraction studies reveal that these framework solids are two-dimensional (2D) networks as opposed to the diamondoid networks obtained when the parent unoxidized 4,4′-bipyridine is used as the linker (Inorg. Chem. 2014, 53, 8959). The two types of voids (viz., smaller intra-D4R and larger inter-D4R) present in these framework solids can be utilized for different types of encapsulation processes. For example, the in situ generated 2D framework 2 encapsulates fluoride ions accompanied by a change in the dimensionality of the framework to yield {[(nC4H9)4N][F(Zn4(dipp)4(BIPYMO)2)]}n (6). The three-dimensional framework 6 represents the first structurally characterized example of a fluoride-ion-encapsulated polymeric coordination compound or a metal-organic framework. The possibility of utilizing inter-D4R voids as hosts for small organic molecules has been explored by treating in situ generated 2 with a series of organic molecules of appropriate size. Framework 2 has been found to be a selective host for benzil and not for other structurally similar molecules such as benzoquinone, benzidine, anthracene, naphthalene, α-pyridoin, etc. The benzil-occluded isolated framework [benzil@{Zn4(dipp)4(BIPYMO)2}]n (7) has been isolated as single crystals, and its crystal structure determination revealed the binding of benzil molecules to the framework through strong π-π interactions.
- Dar, Aijaz A.,Bhat, Gulzar A.,Murugavel, Ramaswamy
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- Bismuth-Based Coordination Polymers with Efficient Aggregation-Induced Phosphorescence and Reversible Mechanochromic Luminescence
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Two bismuth coordination polymers (CPs), (TBA)[BiBr4(bp4mo)] (TBA=tetrabutylammonium) and [BiBr3(bp4mo)2], which are based on the rarely used simple ditopic ligand N-oxide-4,4′-bipyridine (bp4mo), show mechanochromic luminescence (MCL). High solid-state phosphorescence quantum yields of up to 85 % were determined for (TBA)[BiBr4(bp4mo)] (λem=540 nm). Thorough investigations of the luminescence properties combined with DFT and TDDFT calculations revealed that the emission is due to aggregation-induced phosphorescence (AIP). Upon grinding, both samples became amorphous, and their luminescence changed from yellow to orange and red, respectively. Heating or exposure to water vapor led to the recovery of the initial luminescence. These materials are the first examples of mechanochromic phosphors based on bismuth(III).
- Toma, Oksana,Allain, Magali,Meinardi, Francesco,Forni, Alessandra,Botta, Chiara,Mercier, Nicolas
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- 4,4′-bipyridine-N-monoxide. A hybrid ligand for building networks using a combination of metal-ligand and hydrogen-bonding interactions
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The ligand 4,4′-bipyridine-N-monoxide, (BIPYMO) coordinates through the pyridine N-donor to Pt(ii) and Pd(ii) to form square planar [ML 4]2+ complexes and to Cu(ii) and Zn(ii) to form octahedral trans-[M(H2O)2L4]2+ complexes. Single crystal X-ray structures show that these individual building blocks are organized via hydrogen bonding through the external N-oxide O-atoms to form 2D and 3D networks. The Royal Society of Chemistry.
- Hoffart, Dennis J.,Habermehl, Nicolle C.,Loeb, Stephen J.
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- Substituted 2,4-Di(pyridin-2-yl)pyrimidine-Based Ruthenium Photosensitizers for Hydrogen Photoevolution under Red Light
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The photocatalytic reduction of water to form hydrogen gas (H2) is a promising approach to collect, convert, and store solar energy. Typically, ruthenium tris(bipyridine) and its many derivatives are used as photosensitizers (PSs) in a variety of photocatalytic conditions. The bis(terpyridine) analogues, however, have only recently gained attention for this application because of their poor photophysical properties. Yet, by the introduction of electron-donating or -withdrawing groups on the terpyridine ligands, the photophysical and electrochemical properties can be considerably improved. In this study, we report a series of nonsymmetric 2,6-di(pyridin-2-yl)pyrimidine ligands with peripheral pyridine substituents in different positions and their corresponding ruthenium(II) complexes. The presence of the pyrimidine ring stabilizes the lowest unoccupied molecular orbital, leading to a red-shifted emission and prolonged excited-state lifetimes as well as higher luminescence quantum yields compared to analogous terpyridine complexes. Furthermore, all complexes are easier to reduce than the previously reported bis(terpyridine) complexes used as PSs. Interestingly, the pyridine substituent in the 4-pyrimidine position has a greater impact on both the photophysical and electrochemical properties. This correlation between the substitution pattern and properties of the complexes is further investigated by using time-dependent density functional theory. In hydrogen evolution experiments under blue- and red-light irradiation, all investigated complexes exhibit much higher activity compared to the previously reported ruthenium(II) bis(terpyridine) complexes, but none of the complexes are as stable as the literature compounds, presumably because of an additional decomposition pathway of the reduced PS competing with electron transfer from the reduced PS to the catalyst.
- Rupp, Mira T.,Auvray, Thomas,Shevchenko, Natali,Swoboda, Lukas,Hanan, Garry S.,Kurth, Dirk G.
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p. 292 - 302
(2021/01/11)
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- N-methyl-4,4′-bipyridinium and n-methyl-n′-oxide-4,4′- bipyridinium bismuth complexes - Photochromism and photoluminescence in the solid state
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Three bismuth complexes based on N-methyl-4,4′-bipyridinium (hMV +), (hMV)[Bi(hMV)Cl5] (1), and N-methyl-N′-oxide-4, 4′-bipyridinium (MVO+), [Bi(MVO)X4(dmso)] ·dmso [X = Cl (2), Br (3)], are reported. All three compounds show luminescence in the solid state with maxima at 545 nm (yellow for 1) and 560 nm (orange for 2 and 3) with quantum yields up to 10 %. Upon UV irradiation, 1 undergoes a color change from white to blue accompanied by a reduction of the photoluminescence intensity. The analysis of the crystal structure of the three complexes points to a photoinduced charge-transfer (PICT) process at the origin of the photochromism in 1. Three bismuth complexes based on N-methyl-4,4′- bipyridinium (hMV+), (hMV)[Bi(hMV)Cl5] (1), and N-methyl-N′-oxide-4,4′-bipyridinium (MVO+), [Bi(MVO)X4(dmso)]·dmso [X = Cl (2), Br (3)], show strong photoluminescence in the solid state. Upon UV irradiation, 1 undergoes a photoinduced charge-transfer (PICT) process resulting in a color change from white to blue. Copyright
- Toma, Oksana,Mercier, Nicolas,Botta, Chiara
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supporting information
p. 1113 - 1117
(2013/04/10)
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- Ranking relative hydrogen-bond strengths in hydroxybenzoic acids for crystal-engineering purposes
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Systematic co-crystallizations resulting in a total of six new crystal structures involving either 3-hydroxy- or 4-hydroxybenzoic acid, complemented by calculated molecular electrostatic potential surfaces and existing structural data, have shown that in a competitive molecular recognition situation, the -OH moiety is a more effective hydrogen-bond donor than the -COOH moiety which, in turn, highlights that electrostatic charge can offer more useful guidance than acidity for predicting competitive hydrogen-bond preferences.
- Aakeroey, Christer B.,Epa, Kanishka,Forbes, Safiyyah,Schultheiss, Nathan,Desper, John
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p. 14998 - 15003
(2013/11/06)
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- Syntheses of bipyridine-N-oxides and bipyridine-N,N'-dioxides
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Dimethyldioxirane (DMD) was used to synthesize heterocyclic aromatic N-oxides enabling the product isolation and reaction solutions to be free of potentially dangerous peroxide intermediates. Additionally, this work combines important crystallographic, spectroscopic, and melting point data to shed light on inconsistent literature previously reported for the identity of 2,4'-bipyridine-N'-oxide.
- McKay,Lashlee III,Maina,Wheeler,Brown
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experimental part
p. 181 - 188
(2010/07/05)
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- Crystalline organization and bonding of N-perfluoroacylpyridiniumaminides
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N-Perfluoroacylpyridiniumaminides are stable crystalline solids characterized by a potentially useful set of properties. The molecular geometries resulting from the determination of the crystal structures of three members of the series suggest that, due to the presence of the perfluoroalky chains, the electron density on the formally negatively charged nitrogen of the ylide system is reduced. The N-N and the OC-N bonds in the systems are shortened and the whole molecules are stabilized as compared to non-fluorinated N-alkanoylpyridiniumaminides. The packing in the crystals can be qualitatively understood as a compromise between two distinct effects: the tendency to segregate, of the fluorocarbon groups on one hand and the bipyridinium blocks on the other, as in the case of 4b or c, the formation of weak interactions involving the pyridinium hydrogens and the most effective hydrogen bond accepting atoms (i.e. O and N).The latter effect leads to disorder of the perfluoroalkyl chains in 4a. In 4b and c, even at room temperature, a surprisingly ordered arrangement of the segregated perfluoropropyl chains is observed, showing a clear tendency to helicoidal conformation related to fluorine-fluorine repulsion.
- Caronna, Tullio,Corradi, Eleonora,Valdo Meille, Stefano,Novo, Barbara,Resnati, Giuseppe,Sidoti, Giancarlo
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p. 183 - 190
(2007/10/03)
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- Novel chiral oxazoline ligands for potential charge-transfer effects in the Rh(I)-catalysed enantioselective hydrosilylation
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Novel 2-(4,4′-bipyridin-2-yl)oxazolines, bearing a chiral oxazoline moiety, were synthesised starting from 4,4′-bipyridine and selectively monomethylated in the N′-position. After coordination to rhodium these electron-poor ligands are supposed to exhibit charge-transfer effects with electron-donating substrates in the Rh(I)-catalysed enantioselective hydrosilylation (see next publication). Similar effects were expected from 4,4′-bipyridine- and pyrazine-bisoxazolines after complexation with rhodium. For comparison 2-(4-phenylpyridin-2-yl)oxazoline ligands were synthesised. Rh(I)-complexes of selected ligands were prepared and characterised, including an X-ray structure analysis.
- Brunner, Henri,Stoeriko, Reinhard,Rominger, Frank
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p. 771 - 781
(2007/10/03)
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- Heterosupramolecular Chemistry: Synthetic Strategies for the Covalent and Noncovalent Assembly and Organization of Nanocrystals and Molecules
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Described are the preparation of nanocrystals and the synthesis of molecules that may be covalently or noncovalently assembled in solution to yield heterosupermolecules possessing a well-defined heterosupramolecular function. Also described are preparative and synthetic methods that yield organized assemblies of heterosupermolecules possessing an addressable heterosupramolecular function. Finally, the development of these synthetic strategies to permit the covalent and noncovalent assembly and organization of a wide range of condensed phase and molecular components is outlined.
- Nagarajo Rao,Fitzmaurice, Donald
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p. 902 - 915
(2007/10/03)
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- Reactivity of perfluoro-(cis-2,3-dialkyloxaziridines) with heteroaromatic nitrogen compounds
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Pyridine N-oxides 3 are exclusively formed under particularly mild conditions when perfluorinated dialkyloxaziridines 1 are reacted with pyridine derivatives 2 bearing a substituent at the 2-position. Starting from pyridines substituted at the 3- and 4-positions, the previously unreported N-perfluoroacylpyridiniumaminides 4 are also produced and isolated as solid, stable compounds. Bis(pyridinium-N-aminides) 9, which have been prepared starting from bis-pyridine substrates and pyridazine and quinoxaline starting materials, also show the same reactivity. This behaviour reveals how oxaziridines 1 can work as both animating and oxygenating agents.
- Bernardi, Rosanna,Novo, Barbara,Resnati, Giuseppe
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p. 2517 - 2521
(2007/10/03)
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- Studies on organometallic compounds. IX. Synthesis of bipyridine N-oxides and terpyridines by palladium catalyzed cross-coupling reaction of trimethylstannylpyridines with bromopyridines
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Reaction of trimethylstannylpyridines with bromopyridines in the presence of Pd(PPh3)4 directed toward a practical use was accomplished, giving all nine pyridinylpyridine N-oxides in satisfactory yields. Similarly, nicotelline and 2,2′:6′,2″-terpyridine were produced in good yields.
- Yamamoto, Yutaka,Tanaka, Takuo,Yagi, Masayoshi,Inamoto, Masayuki
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p. 189 - 194
(2007/10/02)
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- From bipyridines to tobacco alkaloids and related compounds
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Starting from structural considerations which led to the hypothesis that a chemical relationship could exist between two families of natural compounds (mainly pyridinic and pyrrolidinic alkaloids), experiments were carried out in order to establish a correlation route between the two studied classes. Of special interest was the central position of nicotine in these studies, and the main part of this work was devoted to the synthesis of nicotine starting from bipyridines. It was thus necessary to determine the conditions for selective reactions on one aromatic ring of bipyridines (N-methylation, N-oxidation and reduction of the heterocycle). Ring contraction procedure allowed us to obtain nicotine from the parent compound (3,3′-bipyridine). Complementary studies yielded various isomers of piperidinylpyridines (hexahydro derivatives of bipyridines) in a regiochemically controlled manner by means of original methods. Elsevier,.
- Plaquevent, Jean-Christophe,Chichaoui, Ilhame
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p. 369 - 379
(2007/10/03)
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- Reduction Regiospecifique des Bipyridines
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A method for the specific reduction of bipyridines through the use of the N-oxo derivatives is described.
- Plaquevent, Jean-Christophe,Chichaoui, Ilhame
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p. 5287 - 5288
(2007/10/02)
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