- Role of the Bridging Group in Bis-Pyridyl Ligands: Enhancing Both the Photo- and Electroluminescent Features of Cationic (IPr)CuI Complexes
-
We report on the benefits of changing the bridging group X of bis-pyridyl ligands, that is, Py-X-Py where X is NH, CH2, C(CH3)2, or PPh, on the photo- and electroluminescent properties of a new family of luminescent cationic H-heterocyclic carbene (NHC) copper(I) complexes. A joint experimental and theoretical study demonstrates that the bridging group affects the molecular conformation from a planar-like structure (X is NH and CH2) to a boat-like structure (X is C(CH3)2 and PPh), leading to i) four-fold enhancement of the photoluminescence quantum yield (?em) without affecting the thermally activated delayed fluorescence mechanism, and ii) one order of magnitude reduction of the ionic conductivity (σ) of thin films. This leads to an overall enhancement of the device efficacy and luminance owing to the increased ?em and the use of low applied driving currents.
- Elie, Margaux,Weber, Michael D.,Di Meo, Florent,Sguerra, Fabien,Lohier, Jean-Fran?ois,Pansu, Robert B.,Renaud, Jean-Luc,Hamel, Matthieu,Linares, Mathieu,Costa, Rubén D.,Gaillard, Sylvain
-
-
Read Online
- Boron Dipyridylmethene (DIPYR) Dyes: Shedding Light on Pyridine-Based Chromophores
-
Boron dipyrromethene (BODIPY) derivatives have found widespread utility as chromophores in fluorescent applications, but little is known about the photophysical properties of pyridine-based BODIPY analogues, dipyridylmethene dyes. Indeed, it has been repo
- Golden, Jessica H.,Facendola, John W.,Sylvinson, Daniel M.R.,Baez, Cecilia Quintana,Djurovich, Peter I.,Thompson, Mark E.
-
-
Read Online
- Synthesis of methylene- and methine-bridged oligopyridines
-
A variety of methylene- and methine-bridged oligopyridines are conveniently accessible through stepwise nucleophilic aromatic substitution with fluoro-substituted pyridines. The yields achieved are regularly above 90%. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Dyker, Gerald,Muth, Oliver
-
-
Read Online
- Synthesis and Isomeric Analysis of RuII Complexes Bearing Pentadentate Scaffolds
-
A RuII-pentadentate polypyridyl complex [RuII(κ-N5-bpy2PYMe)Cl]+ (1+, bpy2PYMe = 1-(2-pyridyl)-1,1-bis(6-2,2′-bipyridyl)ethane) and its aqua derivative [RuII(κ-N5-bpy2PYMe)(H2O)]2+ (22+) were synthesized and characterized by experimental and computational methods. In MeOH, 1+ exists as two isomers in different proportions, cis (70%) and trans (30%), which are interconverted under thermal and photochemical conditions by a sequence of processes: chlorido decoordination, decoordination/recoordination of a pyridyl group, and chlorido recoordination. Under oxidative conditions in dichloromethane, trans-12+ generates a [RuIII(κ-N4-bpy2PYMe)Cl2]+ intermediate after the exchange of a pyridyl ligand by a Cl- counterion, which explains the trans/cis isomerization observed when the system is taken back to Ru(II). On the contrary, cis-12+ is in direct equilibrium with trans-12+, with absence of the κ-N4-bis-chlorido RuIII-intermediate. All these equilibria were modeled by density functional theory calculations. Interestingly, the aqua derivative is obtained as a pure trans-[RuII(κ-N5-bpy2PYMe)(H2O)]2+ isomer (trans-22+), while the addition of a methyl substituent to a single bpy of the pentadentate ligand leads to the formation of a single cis isomer for both chlorido and aqua derivatives [RuII(κ-N5-bpy(bpyMe)PYMe)Cl]+ (3+) and [RuII(κ-N5-bpy(bpyMe)PYMe)(H2O)]2+ (42+) due to the steric constraints imposed by the modified ligand. This system was also structurally and electrochemically compared to the previously reported [RuII(PY5Me2)X]n+ system (X = Cl, n = 1 (5+); X = H2O, n = 2 (62+)), which also contains a κ-N5-RuII coordination environment, and to the newly synthesized [RuII(PY4Im)X]n+ complexes (X = Cl, n = 1 (7+); X = H2O, n = 2 (82+)), which possess an electron-rich Hκ-N4C-RuII site due to the replacement of a pyridyl group by an imidazolic carbene.
- Gil-Sepulcre, Marcos,Axelson, Jordan C.,Aguiló, Joan,Solà-Hernández, Lluís,Francàs, Laia,Poater, Albert,Blancafort, Lluís,Benet-Buchholz, Jordi,Guirado, Gonzalo,Escriche, Lluís,Llobet, Antoni,Bofill, Roger,Sala, Xavier
-
-
Read Online
- Condensation of 2-pyridylmethyllithium nucleophiles and pyridine electrophiles as a convenient synthetic route to polydentate chelating N-donor ligands
-
Condensation of 2-pyridylmethyllithium or (6-methyl-2-pyridyl)methyllithium nucleophiles and pyridine, 2-picoline, or 4-tert-butylpyridine as electrophiles leads to new polydentate N-donor ligands, methyl-, tert-butyl-substituted tripyridinedimethanes, or to tripyridinedimethane itself, in good or high yields. Depending on the reagent ratio, solvent used, and reaction conditions, the corresponding intermediate dipyridinemethanes can be minor by-product or major products of the condensation. In contrast to 2-pyridylmethyllithium, lithiated 2-isopropylpyridine does not react with pyridine electrophiles. Vice versa, nucleophilic substitution at the C(2)-pyridine carbon of 2,2-bis(2-pyridyl)propane with 2-pyridylmethyllithium takes place to produce products of condensation of 2-isopropylpyridine and dipyridylmethyllithium. DFT calculations of the Gibbs free energies of reactions combined with pKa values of the CH-acids involved help to explain the reactivity observed.
- Vedernikov,Miftakhov,Borisoglebski,Caulton,Solomonov
-
-
Read Online
- Synthesis, Structure, and DFT Analysis of the THF Solvate of 2-Picolyllithium: A 2-Picolyllithium Solvate with Significant Carbanionic Character
-
Previous studies of different solvates of 2-methylpyridyllithium (2-picolyllithium) have uncovered electronic structures corresponding to aza-allyl and enamido resonance forms of the metallated pyridine-based compounds. Here, we report the synthesis and characterization of [2-CH2Li(THF)2C5H4N], a new THF solvate. X-ray crystallographic studies reveal a dimeric arrangement featuring a non-planar eight-membered [NCCLi]2 ring, in which the primary cation-anion interaction is between the central Li atom and the C atom of the deprotonated methyl group [length, 2.285(2) ?], suggesting a new carbanionic resonance structure for this 2-picolyllithium series. The significant carbanionic character of [2-CH2Li(THF)2C5H4N] was confirmed by gas-phase DFT calculations [B3LYP/6-311+G(d)] with the calculated electron density interrogated by means of quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. For comparison these computational analyses were also performed on the literature structures of [2-CH2Li(2-Picoline)C5H4N] and [2-CH2Li(PMDETA)C5H4N]. In a reactivity study, [2-CH2Li(THF)2C5H4N] was found to undergo nucleophilic addition to pyridine to generate dipyridylmethane in a good yield.
- Brouillet, Etienne V.,Kennedy, Alan R.,Kr?mer, Tobias,Mulvey, Robert E.,Robertson, Stuart D.,Stewart, Alexander,Towie, Stephen
-
p. 726 - 733
(2020/02/20)
-
- C-Bridged Bispyrrolidines and Bispiperidines as New Ligands
-
The preparation of methylene-bridged C2-symmetric nitrogen-heterocycles as a new class of ligands is described, including methylene-bridged pyridines, quinolones, piperidines and pyrrolidines. These methylene-bridged aromatic systems are obtained via a microwave assisted Ziegler-type reaction. The separation of diastereomers and the application of the copper complexes of these ligands for cyclopropanation reactions proves the applicability of these new types of ligands.
- Stumpf, Tim-Daniel J.,Steinbach, Manfred,H?ltke, Magdalene,Heuger, Gerold,Grasemann, Franka,Fr?hlich, Roland,Schindler, Siegfried,G?ttlich, Richard
-
p. 5538 - 5547
(2018/10/25)
-
- Direct Triflylation of Benzylic C—H Bonds with Pyridine as a Directing Group
-
The first example of benzylic C—H triflylation was accomplished with pyridine as a directing group. The reaction of various 2-benzylpyridines and (CF3SO2)2O in the presence of NEt3 in CH2Cl2 proceeded smoothly to afford the corresponding benzyl triflones in moderate to high yields.
- Yang, Jun,Hu, Juanjuan,Huang, Yangen,Xu, Xiuhua,Qing, Fengling
-
supporting information
p. 867 - 870
(2017/06/27)
-
- Versatile C(sp2)?C(sp3) Ligand Couplings of Sulfoxides for the Enantioselective Synthesis of Diarylalkanes
-
The reaction of chiral (hetero)aryl benzyl sulfoxides with Grignard reagents affords enantiomerically pure diarylalkanes in up to 98 % yield and greater than 99.5 % enantiomeric excess. This ligand coupling reaction is tolerant to multiple substitution patterns and provides access to diverse areas of chemical space in three operationally simple steps from commercially available reagents. This strategy provides orthogonal access to electron-deficient heteroaromatic compounds, which are traditionally synthesized by transition metal catalyzed cross-couplings, and circumvents common issues associated with proto-demetalation and β-hydride elimination.
- Dean, William M.,?iau?iulis, Mindaugas,Storr, Thomas E.,Lewis, William,Stockman, Robert A.
-
p. 10013 - 10016
(2016/08/16)
-
- A new class of luminescent Cu(i) complexes with tripodal ligands-TADF emitters for the yellow to red color range
-
A new class of emissive and neutral Cu(i) compounds with tripodal ligands is presented. The complexes were characterized chemically, computationally, and photophysically. Under ambient conditions, the powders of the compounds exhibit yellow to red emission with quantum yields ranging from about 5% to 35%. The emission represents a thermally activated delayed fluorescence (TADF) combined with a short-lived phosphorescence which represents a rare situation and is a consequence of high spin-orbit coupling (SOC). In the series of the investigated compounds the non-radiative rates increase with decreasing emission energy according to the energy gap law while the radiative rate is almost constant. Furthermore, a well-fit linear dependence between the experimental emission energies and the transition energies calculated by DFT and TD-DFT methods could be established, thus supporting the applicability of these computational methods also to Cu(i) complexes.
- Gneu?, Timo,Leitl, Markus J.,Finger, Lars H.,Rau, Nicholas,Yersin, Hartmut,Sundermeyer, J?rg
-
p. 8506 - 8520
(2015/05/20)
-
- Triazolopyridines. Part 30.1 Hydrogen transfer reactions; Pyridylcarbene formation
-
The transfer hydrogenation reaction of [1,2,3]triazolo[1,5-a]pyridines with Pd/C/Zn or Pd(OH)2/C/Zn in water, ethanol or water/ethanol mixture has been explored. 4,5,6,7-Tetrahydrotriazolopyridines were obtained in good to medium yields. In addition, under the same conditions 2-substituted pyridines were also formed as a result of intermediate pyridylcarbene formation, by triazole ring opening and loss of nitrogen.
- Abarca, Belen,Adam, Rosa,Alom, Shamim,Ballesteros, Rafael,Lopez-Molina, Sonia
-
p. 175 - 186
(2014/03/21)
-
- A detailed study of acetate-assisted C-H activation at palladium(IV) centers
-
This report describes a detailed investigation of acetate-assisted C-H activation at PdIV centers supported by the tris(2-pyridyl)methane (Py3CH) ligand. Mechanistic information about this transformation has been obtained through the following: (i) extensive one- and two-dimensional NMR analysis, (ii) reactivity studies of a series of substituted analogues, and (iii) isotope effect studies. These experiments all suggest that C-H activation at [(Py3CH)PdIV(biphenyl)Cl2]+ occurs via a multistep process involving chloride-to-acetate ligand exchange followed by conformational and configurational isomerization and then C-H cleavage. The data also suggest that C-H cleavage proceeds via an acetate-assisted mechanism with the carboxylate likely serving as an intramolecular base. The viability of acetate-assisted C-H activation at high valent palladium has important implications for the design and optimization of catalytic processes involving this transformation as a key step.
- Maleckis, Ansis,Kampf, Jeff W.,Sanford, Melanie S.
-
supporting information
p. 6618 - 6625
(2013/06/05)
-
- Synthesis and photoluminescent properties of new ceramidine derivatives
-
A series of new ceramidine derivatives 8a-f has been synthesized in 4-5 steps involving a Wittig reaction of ceramidonine with various triphenylphosphonium bromides. Their UV and photoluminescence (PL) properties are reported. The compounds showed medium to strong PL between 502 and 522 nm at a concentration of 1 × 10-5 M CH2Cl2.
- Park, Byung Sun,Lee, Sang Woo,Kim, In Tae,Tae, Jin Sung,Lee, So Ha
-
experimental part
p. 66 - 73
(2012/03/26)
-
- Palladium-catalyzed 2-pyridylmethyl transfer from 2-(2-pyridyl)-ethanol derivatives to organic halides by chelation-assisted cleavage of unstrained Csp3-Csp3 bonds
-
(Chemical Equation Presented) Making a break for it: Treatment of 2-(2-pyridyl)ethanol derivatives with aryl chlorides in the presence of a palladium catalyst results in the transfer of the pyridylmethyl moiety of the alcohol to yield the corresponding (2-pyridyl-methyl)arene. The reaction proceeds by chelation-assisted cleavage of an Csp3-C5p3 bond (see scheme) followed by formation of a carbon-carbon bond.
- Niwa, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
-
p. 2643 - 2645
(2008/02/13)
-
- Diarylalkylpiperazines active on the lower urinary tract
-
Disclosed herein are novel compounds and methods for the treatment of disorders of the lower urinary tract. The novel compounds are diarylalkylpiperazine derivatives. The methods comprise the administration of the novel compounds of the invention, and other compounds that bind to 5HT1A receptors, for treating disorders of the lower urinary tract.
- -
-
Page/Page column 21
(2010/02/11)
-
- Catalysts
-
The invention describes ligands of formula (I), wherein LIG represents an η5-ligand substituted by a group R1 and a group (R″)m; X represents a 1 to 3 atom bridge; Y represents a nitrogen or phosphorus atom; Z represents a carbon, nitrogen or phosphorus atom.
- -
-
-
- BISPYRIDYL- AND BISQUINOLYLMETHANES. NMR-BASED CHARGE MAPPING OF THE CARBANIONS AND METAL LIGAND PROPERTIES
-
Nmr evidence is obtained for mixtures of geometrical stereoisomers of carbanions in DMSO solution of bis(4-)- and bis(2-pyridyl)methane (1) and (2), bis(2-pyridyl)acetonitrile (3), and bis(2-quinolyl)methane (4).When incorporated into ?-charge/shift relat
- Abbotto, Alessandro,Bradamante, Silvia,Pagani, Giorgio A.,Rzepa, Henry,Stoppa, Federica
-
p. 757 - 776
(2007/10/02)
-
- Synthesis of Symmetrical Poly(pyridin-2-yl)ethane Ligands
-
Reaction of lithium derivatives of pyridin-2-ylmethanes, (C5H4N)CRR'-Li+, with mercury (II) iodide results in precipitation of mercury, and formation of symmetrical poly(pyridin-2-yl)ethanes 2 (R = H, R' = Ph; R = Me, R' = Ph; R =
- Canty, Allan J.,Minchin, Nigel J.
-
p. 1063 - 1069
(2007/10/02)
-
- Flash Vacuum Pyrolysis of Substituted Pyridine N-Oxides and Its Application to Syntheses of Heterocyclic Compounds
-
Flash vacuum pyrolysis of 2-picoline N-oxide gave 2-picoline, pyridine, 2-ethylpyridine, 2-vinylpyridine, 2-pyridylmethanol, bis(2-pyridyl)methane, 1,2-bis(2-pyridyl)ethane, and 1,2-bis(2-pyridyl)ethylene.These reactions are explained by intermediary participation of the 2-picolyl radical.Flash vacuum pyrolysis of methyl-substituted 2-benzylpyridine N-oxides led to methyl-substituted pyridoindoles or to benzoquinoline in moderate yields.
- Ohsawa, Akio,Kawaguchi, Takayuki,Igeta, Hiroshi
-
p. 3497 - 3503
(2007/10/02)
-
- FLASH VACUUM PYROLYSIS OF 2-PICOLINE N-OXIDE. FORMATION OF 2-PICOLYL RADICAL
-
The flash vacuum pyrolysis of 2-picoline N-oxide was found to give 2-picoline, pyridine, 2-vinylpyridine, bis(2-pyridyl)methane, and 1,2-bis(2-pyridyl)ethane.From the mechanistic consideration of the formation of these products, intermediacy of 2-picolyl radical (i.e., 2-pyridylmethyl radical) is strongly suggested.Keywords: flash vacuum pyrolysis; thermolysis; picoline N-oxides; heterocycles; radical reaction; radical coupling; picolyl radical; pyridylmethyl radical
- Ohsawa, Akio,Kawaguchi, Takayuki,Igeta, Hiroshi
-
p. 1481 - 1483
(2007/10/02)
-