6311-60-0Relevant articles and documents
Non-photoisomerizable butterfly shaped tetrasubstituted azobenzenes: Synthesis and photophysical studies
Raman, Arunachalam,Neelambra, Afeefah U.,Karunakaran, Venugopal,Easwaramoorthi, Shanmugam
, p. 8818 - 8822 (2020)
Thetrans-azobenzene (AB) substituted derivatives with bulky carbazole (1), phenothiazine (2), and phenyl (3) have been synthesized to understand the effect of steric crowding around the -NN- linkage on the photoisomerization process. The substituents maintain orthogonality to the azobenzene plane and the electronic properties exhibit a combination of individual chromophores. Irradiation of1and2with various light sources including a 365 nm pen-ray lamp, and a 150 W Xe-Hg lamp, and even exposure to sunlight for a week does not yield thecisisomer revealing the exceptional photostability of the synthesized azobenzene derivatives. These studies suggest that possessing steric crowding around the azo linkage would be a potential strategy to develop photostable azobenzene-based functional materials.
Azo bond formation on metal surfaces
Meng, Xiangzhi,Klaasen, Henning,Viergutz, Lena,Schulze Lammers, Bertram,Witteler, Melanie C.,M?nig, Harry,Amirjalayer, Saeed,Liu, Lacheng,Neugebauer, Johannes,Gao, Hong-Ying,Studer, Armido,Fuchs, Harald
supporting information, p. 1458 - 1464 (2020/12/14)
The formation of azo compounds via redox cross-coupling of nitroarenes and arylamines, challenging in solution phase chemistry, is achieved by on-surface chemistry. Reaction products are analyzed with a cryogenic scanning tunneling microscope (STM) and X-ray photoelectron spectroscopy (XPS). By using well-designed precursors containing both an amino and a nitro functionality, azo polymers are prepared on surface via highly efficient nitro-amino cross-coupling. Experiments conducted on other substrates and surface orientations reveal that the metal surface has a significant effect on the reaction efficiency. The reaction was further found to proceed from partially oxidized/reduced precursors in dimerization reactions, shedding light on the mechanism that was studied by DFT calculations.
meta-Nitration of Arenes Bearing ortho/para Directing Group(s) Using C?H Borylation
Li, Xuejing,Deng, Xingwang,Coyne, Anthony G.,Srinivasan, Rajavel
supporting information, p. 8018 - 8023 (2019/05/29)
Herein, we report the meta-nitration of arenes bearing ortho/para directing group(s) using the iridium-catalyzed C?H borylation reaction followed by a newly developed copper(II)-catalyzed transformation of the crude aryl pinacol boronate esters into the corresponding nitroarenes in a one-pot fashion. This protocol allows the synthesis of meta-nitrated arenes that are tedious to prepare or require multistep synthesis using the existing methods. The reaction tolerates a wide array of ortho/para-directing groups, such as ?F, ?Cl, ?Br, ?CH3, ?Et, ?iPr ?OCH3, and ?OCF3. It also provides regioselective access to the nitro derivatives of π-electron-deficient heterocycles, such as pyridine and quinoline derivatives. The application of this method is demonstrated in the late-stage modification of complex molecules and also in the gram-scale preparation of an intermediate en route to the FDA-approved drug Nilotinib. Finally, we have shown that the nitro product obtained by this strategy can also be directly converted to the aniline or hindered amine through Baran's amination protocol.