1132-37-2Relevant academic research and scientific papers
Role of the Bridging Group in Bis-Pyridyl Ligands: Enhancing Both the Photo- and Electroluminescent Features of Cationic (IPr)CuI Complexes
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
, p. 16328 - 16337 (2017)
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.
Boron Dipyridylmethene (DIPYR) Dyes: Shedding Light on Pyridine-Based Chromophores
Golden, Jessica H.,Facendola, John W.,Sylvinson, Daniel M.R.,Baez, Cecilia Quintana,Djurovich, Peter I.,Thompson, Mark E.
, p. 7215 - 7222 (2017)
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
Synthesis of methylene- and methine-bridged oligopyridines
Dyker, Gerald,Muth, Oliver
, p. 4319 - 4322 (2004)
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.
Synthesis and Isomeric Analysis of RuII Complexes Bearing Pentadentate Scaffolds
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
, p. 11216 - 11229 (2016)
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.
Condensation of 2-pyridylmethyllithium nucleophiles and pyridine electrophiles as a convenient synthetic route to polydentate chelating N-donor ligands
Vedernikov,Miftakhov,Borisoglebski,Caulton,Solomonov
, p. 406 - 416 (2002)
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.
Synthesis, Structure, and DFT Analysis of the THF Solvate of 2-Picolyllithium: A 2-Picolyllithium Solvate with Significant Carbanionic Character
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)
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.
C-Bridged Bispyrrolidines and Bispiperidines as New 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)
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.
Direct Triflylation of Benzylic C—H Bonds with Pyridine as a Directing Group
Yang, Jun,Hu, Juanjuan,Huang, Yangen,Xu, Xiuhua,Qing, Fengling
supporting information, p. 867 - 870 (2017/06/27)
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.
Versatile C(sp2)?C(sp3) Ligand Couplings of Sulfoxides for the Enantioselective Synthesis of Diarylalkanes
Dean, William M.,?iau?iulis, Mindaugas,Storr, Thomas E.,Lewis, William,Stockman, Robert A.
, p. 10013 - 10016 (2016/08/16)
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.
A new class of luminescent Cu(i) complexes with tripodal ligands-TADF emitters for the yellow to red color range
Gneu?, Timo,Leitl, Markus J.,Finger, Lars H.,Rau, Nicholas,Yersin, Hartmut,Sundermeyer, J?rg
, p. 8506 - 8520 (2015/05/20)
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.
