2,4-Diarylquinolines: Synthesis, Absorption and Emission Properties

Adeloye, Adewale O.; Mphahlele, Malose J.

doi:10.3184/174751914x13945617338344

Cited by 6 publications

(5 citation statements)

References 24 publications

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“…For the new organophotocatalyst design, we hypothesized that engineering the C2 and/or C4 positions of quinoline skeletons with π-extended substituents could be advantageous, moving their absorption to the visible-light region and simultaneously blocking their radicophilic sites. 10 By inspecting some representative photocatalysts (e.g., Fukuzumi's and Nicewicz's catalysts), cationic nitrogen centers appear to be common traits. As such, we expected that simple protonation of our quinoline photocatalyst could exert an equal effect.…”

Section: Resultsmentioning

confidence: 99%

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H₂ Release

Huang

Han

et al. 2021

ACS Catal.

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Designing molecular photocatalysts for potent photochemical reactivities ranks among the most challenging but rewarding endeavors in synthetic photochemistry. Herein, we document a quinoline-based organophotoredox catalyst, 2,4-bis(4-methoxyphenyl)quinoline (DPQN2,4‑di‑OMe ), that could be assembled via the facile aldehyde–alkyne–amine (A3) couplings. Unlike the reported photocatalysts, which impart their photoreactivities as covalently linked entities, our mechanistic studies suggested a distinct proton activation mode of DPQN2,4‑di‑OMe . Simply upon protonation, DPQN2,4‑di‑OMe could reach a highly oxidizing excited state under visible-light irradiation (E*1/2 = +1.96 V vs a standard calomel electrode, SCE). On this basis, the synergistic merger of DPQN2,4‑di‑OMe and cobaloxime formulated an oxidative cross-coupling platform, enabling the Minisci alkylation and various C–C bond-forming reactions with a diverse pool of radical precursors in the absence of chemical oxidants. The catalytic loading of DPQN2,4‑di‑OMe could be minimized to 0.025 mol % (TON = 3360), and a polymer-supported photocatalyst, DPQN2,4-di-OR@PS, was prepared to facilitate catalyst recycling (at a 0.50 mmol % loading and up to five times without significant loss of photosynthetic efficiency).

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Section: Resultsmentioning

confidence: 99%

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H₂ Release

Huang

Han

et al. 2021

ACS Catal.

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“…The NMR data were in agreement with those reported in the literature. 29 2-(Perfluorophenyl)-4-phenylquinoline (5f). Following the general procedure, a J.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Mechanistic Insights into the B(C₆F₅)₃-Initiated Aldehyde–Aniline–Alkyne Reaction To Form Substituted Quinolines

Fasano¹,

Radcliffe

Ingleson

2017

Organometallics

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A substoichiometric quantity of the Lewis acid B(C 6 F 5 ) 3 is sufficient to initiate the aldehyde−amine−alkyne reaction, in a one-pot methodology that enables the synthesis of a range of functionalized quinolines. Optimization studies revealed that key requirements for the high-yielding tricomponent reaction initiated by B(C 6 F 5 ) 3 at raised temperatures include an excess of the in situ generated imine (which acts as a hydrogen acceptor) and an alkyne substituent able to stabilize positive charge buildup during the cyclization. Mechanistic experiments revealed that under these conditions B(C 6 F 5 ) 3 is acting as a Lewis acid-assisted Brønsted acid, with H 2 O−B(C 6 F 5 ) 3 being the key species enabling catalytic quinoline formation. This was indicated by deuterium labeling studies and the observation that the cyclization of N-(3-phenylpropargyl)aniline using B(C 6 F 5 ) 3 under anhydrous conditions afforded the zwitterion [(N-H-3-B(C 6 F 5 ) 3 -4-Ph-quinolinium], which does not undergo protodeboronation to release B(C 6 F 5 ) 3 and the quinoline product under a range of conditions. Finally, a brief substrate scope exploration demonstrated that this is an operationally simple and effective methodology for the production of functionalized quinolines.

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“…The synthesis of the reported compounds first involves the use of the 2-aryl-4-chloroquinolines ( 1a – d ) as substrates for palladium-catalyzed Suzuki cross-coupling with 4-(fluorophenylvinyl)boronic acid and 4-(methoxyphenylvinyl)boronic acid (1.2 equiv.) as coupling partners in the presence of Pd(PPh 3 ) 4 –PCy 3 catalyst complex as Pd(0) source and potassium carbonate as a base in 3:1 dioxane-water mixture ( v/v ) under reflux ( Scheme 1 ) [ 29 ]. The prepared 2-aryl-4-(4-fluorophenylvinyl)quinolines ( 2a – d ) and 2-aryl-4-(4-methoxyphenylvinyl)quinolines ( 3a – d ) were used in this investigation as models for comparative studies in the electronic absorption and emission properties, and a further electrochemical studies for the corresponding homoleptic Ir(III) complexes of the type [Ir(N ˄ C) 3 ], coded as 4a – d and 5a – d , respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Each oxidation potential was calibrated with the use of ferrocene/ferrocenium as a reference. The reported complexes were examined at a concentration of 10 −3 M and supporting electrolyte at 10 −1 M. The synthesis and analytical data of 1 have been described elsewhere [ 29 ].…”

Section: Methodsmentioning

confidence: 99%

Spectroscopic, Electrochemical and DFT Studies of Phosphorescent Homoleptic Cyclometalated Iridium(III) Complexes Based on Substituted 4-Fluorophenylvinyl- and 4-Methoxyphenylvinylquinolines

et al. 2017

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This study reports the synthesis and comparative investigation of the substituent effects of a new series of highly luminescent homoleptic tris-cyclometalated iridium(III) complexes of the type [Ir(N˄C)3]. These are based on two ligand type derivatives comprising of 4-fluorophenylvinylquinolines and 4-methoxyphenylvinylquinolines with electron-donating and/or electron-withdrawing groups as aryl substituents at 2-position. The structures of the ligands and their complexes were characterized by means of FT-IR, UV-Vis and NMR spectrometry complemented with photoluminescence and cyclic voltammetry. The photophysical properties of 2-aryl-4-(4-fluorophenylvinyl)quinoline and its corresponding complex were also studied using the density functional theory method. The photoluminescent properties of the ligands and the corresponding complexes showed high fluorescent intensities and quantum yields in solvents of different polarities. The photoluminescence spectra of the complexes in solid film, showed common transmission curves at longer wavelengths maximum (λem = 697 nm) possibly originating from the interference of scattered light of higher-order transmission of monochromators.

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2,4-Diarylquinolines: Synthesis, Absorption and Emission Properties

Abstract: The absorption and emission spectra of series of 2,4-diarylquinolines prepared via palladium catalysed Suzuki-Miyaura cross-coupling of 2-aryl-4-chloroquinolines with arylboronic acids were measured in solution to understand the influence of substituents on intramolecular charge transfer.

Cited by 6 publications

References 24 publications

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H₂ Release

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H₂ Release

Mechanistic Insights into the B(C₆F₅)₃-Initiated Aldehyde–Aniline–Alkyne Reaction To Form Substituted Quinolines

Spectroscopic, Electrochemical and DFT Studies of Phosphorescent Homoleptic Cyclometalated Iridium(III) Complexes Based on Substituted 4-Fluorophenylvinyl- and 4-Methoxyphenylvinylquinolines

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2,4-Diarylquinolines: Synthesis, Absorption and Emission Properties

Abstract: The absorption and emission spectra of series of 2,4-diarylquinolines prepared via palladium catalysed Suzuki-Miyaura cross-coupling of 2-aryl-4-chloroquinolines with arylboronic acids were measured in solution to understand the influence of substituents on intramolecular charge transfer.

Cited by 6 publications

References 24 publications

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H2 Release

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H2 Release

Mechanistic Insights into the B(C6F5)3-Initiated Aldehyde–Aniline–Alkyne Reaction To Form Substituted Quinolines

Spectroscopic, Electrochemical and DFT Studies of Phosphorescent Homoleptic Cyclometalated Iridium(III) Complexes Based on Substituted 4-Fluorophenylvinyl- and 4-Methoxyphenylvinylquinolines

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Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H₂ Release

Development of a Quinolinium/Cobaloxime Dual Photocatalytic System for Oxidative C–C Cross-Couplings via H₂ Release

Mechanistic Insights into the B(C₆F₅)₃-Initiated Aldehyde–Aniline–Alkyne Reaction To Form Substituted Quinolines