3665-72-3Relevant academic research and scientific papers
Ultrafast Observation of a Photoredox Reaction Mechanism: Photoinitiation in Organocatalyzed Atom-Transfer Radical Polymerization
Koyama, Daisuke,Dale, Harvey J. A.,Orr-Ewing, Andrew J.
, p. 1285 - 1293 (2018)
Photoredox catalysis has driven a revolution in the field of organic chemistry, but direct mechanistic insights into reactions of genuine synthetic utility remain relatively scarce. Herein we report ultrafast time-resolved spectroscopic observation of a bimolecular organocatalyzed photoredox reaction, from catalyst photoexcitation through to photoinduced electron transfer (PET) and intermediate formation, using transient vibrational and electronic absorption spectroscopy with sub-picosecond time resolution. Specifically, the photochemical dynamics of initiation in organocatalyzed atom-transfer radical polymerization (O-ATRP) are elucidated for two complementary photoredox organocatalysts (N,N-diaryl-5,10-dihydrophenazines). Following photoexcitation, a dissociative bimolecular electron transfer is observed from the first excited singlet state of both photocatalysts to methyl 2-bromopropionate in dichloromethane, toluene, and dimethylformamide. The photocatalyst excited donor state, ground state, and radical cation are tracked in real time alongside the debrominated radical fragment. Our work challenges previously proposed mechanisms of initiation in O-ATRP and indicates that PET from short-lived excited singlet states can exert control of polymer molecular weight and dispersity by suppressing the steady-state concentration of the reactive debrominated radical. More broadly, we aim to demonstrate the potential of ultrafast absorption spectroscopy to observe directly transient, open-shell intermediates in mechanistic studies of photoredox catalysis.
Ligand-Free Iron-Catalyzed C-F Amination of Diarylamines: A One-Pot Regioselective Synthesis of Diaryl Dihydrophenazines
Aoki, Yuma,O'Brien, Harry M.,Kawasaki, Hiroto,Takaya, Hikaru,Nakamura, Masaharu
supporting information, (2019/01/21)
A one-pot synthesis of various 5,10-diaryl-5,10-dihydrophenazines (DADHPs) from diarylamines has been achieved by using an iron-catalyzed C-F amination. Homodimerization of magnesium diarylamides, followed by defluorinative intramolecular cyclization (dou
Ligand-Free Iron-Catalyzed C-F Amination of Diarylamines: A One-Pot Regioselective Synthesis of Diaryl Dihydrophenazines
Aoki, Yuma,O'Brien, Harry M.,Kawasaki, Hiroto,Takaya, Hikaru,Nakamura, Masaharu
supporting information, p. 461 - 464 (2019/01/23)
A one-pot synthesis of various 5,10-diaryl-5,10-dihydrophenazines (DADHPs) from diarylamines has been achieved by using an iron-catalyzed C-F amination. Homodimerization of magnesium diarylamides, followed by defluorinative intramolecular cyclization (dou
Organic micromolecule material based on 2,6-dimethyl-4-cyanophenyl receptor unit, preparation and application
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Paragraph 0028; 0030; 0031; 0071; 0073; 0074; 0075, (2018/10/19)
The invention belongs to the technical field of organic photoelectric materials, and discloses an organic micromolecule material based on a 2,6-dimethyl-4-cyanophenyl receptor unit, preparation and application. The organic micromolecule material has a structural formula as shown in formula (I), and Ar in the formula shows a phenyl aromatic amine heterocycle or phenyl aromatic amine donor unit. Thematerial has a weak intramolecular charge transfer state, and thus, fluorescence emission of a zone from dark blue to ultraviolet can be realized. Meanwhile, because the molecules have quite short effective conjugated length, the material has high triplet state energy level. In the application of an organic electroluminescent device, the problem of unbalanced charge carriers of a unipolar organicphotoelectric material can be solved effectively, therefore, the structure of the device is simplified, and the performance of the device is improved.
COMPOSITIONS AND METHODS OF PROMOTING ORGANIC PHOTOCATALYSIS
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, (2018/09/12)
The invention provides novel compounds and methods that are useful in promoting reactions that proceed through an oxidative quenching pathway. In certain embodiments, the reactions comprise atom transfer radical polymerization.
Aerobic Oxidative Homo- and Cross-Coupling of Amines Catalyzed by Phenazine Radical Cations
Bri?ar, Rok,Unglaube, Felix,Hollmann, Dirk,Jiao, Haijun,Mejía, Esteban
, p. 13481 - 13490 (2018/11/02)
Phenazine radical cations (PhRCs) were used for the first time as efficient metal-free catalysts for the oxidative homo- and cross-coupling of a variety of different amines. A series of functional PhRCs were prepared, characterized with X-ray diffraction, and their radical character was investigated with DFT calculations. They were tested as catalysts under neat conditions with low oxygen pressure to prepare homo- and cross-coupled aliphatic and aromatic imines in high yields. Although all synthesized phenazines were catalytically active, the highest reaction rates and the best selectivity were achieved using the 5,10-dihydro-5,10-dimethylphenazine radical cation. By means of fluorescence, UV-vis and EPR spectroscopy, a mechanism of the oxidative amine coupling, catalyzed by PhRCs, is proposed.
Facile synthesis of 5,10-diaryl-5,10-dihydrophenazines and application to EL devices
Okamoto, Toshihiro,Terada, Eriko,Kozaki, Masatoshi,Uchida, Manabu,Kikukawa, Shingo,Okada, Keiji
, p. 373 - 376 (2007/10/03)
(Matrix presented) An efficient method for the synthesis of 5,10-diaryldihydrophenazine was developed using a recently developed Pd(0)-mediated cross-coupling reaction. The products 1k and 3c showed excellent properties as hole injection materials in electroluminescent (EL) devices.
