122045-06-1Relevant articles and documents
Anion recognition in aqueous solution by cyclic dinuclear square cage-shaped coordination complexes
Fu, Cai-Ye,Li, Yu-Qian,Chen, Lu,Wang, Yun-Guang,Lin, Li-Rong
, (2019)
Three cyclic dinuclear complexes, namely [M2(H2L)2](ClO4)4 [M = Co2+ (1), Ni2+ (2), Zn2+ (3), H2L = (1,2)-bis-N'-(pyridin-2-ylmethylene)benzohydrazide hydrazine, C26H22N8O2], containing amide and hydrazine groups were synthesized and characterized. Each central metal ion is coordinated with two oxygen atoms and four nitrogen atoms from carbonyl, and pyridine and imine, respectively. The metal ion is six-coordinated and has a slightly deformed octahedral geometry. X-ray crystallographic analyses showed that all the three cyclic dinuclear complexes crystallize in the orthorhombic system, and belong to the C222 space group, with two molecules in each unit cell. The cyclic dinuclear molecule is linked by two H2L ligands with a Z-form-HN-NH-bridge, nearly forming a square coordination cage with edges of length around 8.4 ?. The cyclic dinuclear complexes can recognize acetate and fluoride anions in an acetonitrile solution containing 60% volume water. Recognition is governed by electrostatic interactions in cooperation with the cage structure effect with the mechanism of anion displacement reaction. The results show that the recognition of anions in acetonitrile aqueous solution is an exothermic and entropy-reducing reaction. This suggests that the enthalpy change plays an important role in the presence of highly polar water and highlights the importance of positively charged cage structure effect. A color change from light yellow to dark yellow was clearly observed for complex 3 on addition of acetate or fluoride anions in acetonitrile aqueous solution containing 60% water. Complex 3 can be used for colorimetric “naked eye” recognition of acetate or fluoride anions in acetonitrile aqueous solution. Theoretical calculations based on time dependent density functional theory (TD-DFT) show the agreement between the theoretical results and experimental data.
Pd-catalyzed direct c-h bond sulfonylation of azobenzenes with arylsulfonyl chlorides
Zhang, Duo,Cui, Xiuling,Zhang, Qianqian,Wu, Yangjie
, p. 1517 - 1522 (2015)
Pd(II)-catalyzed C-H sulfonylation of azobenzenes with arylsulfonyl chlorides has been developed. The sulfonylazobenzenes were obtained in moderate to excellent yields for 28 examples. This protocol features high efficiency, wide functional group tolerance, and atom economy.
Oxidative dehydrogenation of hydrazines and diarylamines using a polyoxomolybdate-based iron catalyst
Huang, Lei,Qiu, Shiqin,Wei, Yongge,Xie, Jingyan,Yu, Han,Zeng, Xianghua,Zhao, Weizhe
supporting information, p. 7677 - 7680 (2021/08/09)
We report an efficient method for the oxidative dehydrogenation of hydrazines and diarylamines in aqueous ethanol using Anderson-type polyoxomolybdate-based iron(iii) as a catalyst and hydrogen peroxide as an oxidant. A series of azo compounds and tetraarylhydrazines were obtained in moderate to excellent yields. The reaction conditions and substrate scopes are complementary or superior to those of more established protocols. In addition, the catalyst shows good stability and reusability in water. The preliminary mechanistic studies suggest that a radical process is involved in the reaction.
Electrocatalytic Z → E Isomerization of Azobenzenes
Goulet-Hanssens, Alexis,Utecht, Manuel,Mutruc, Dragos,Titov, Evgenii,Schwarz, Jutta,Grubert, Lutz,Bléger, David,Saalfrank, Peter,Hecht, Stefan
supporting information, p. 335 - 341 (2017/05/16)
A variety of azobenzenes were synthesized to study the behavior of their E and Z isomers upon electrochemical reduction. Our results show that the radical anion of the Z isomer is able to rapidly isomerize to the corresponding E configured counterpart with a dramatically enhanced rate as compared to the neutral species. Due to a subsequent electron transfer from the formed E radical anion to the neutral Z starting material the overall transformation is catalytic in electrons; i.e., a substoichiometric amount of reduced species can isomerize the entire mixture. This pathway greatly increases the efficiency of (photo) switching while also allowing one to reach photostationary state compositions that are not restricted to the spectral separation of the individual azobenzene isomers and their quantum yields. In addition, activating this radical isomerization pathway with photoelectron transfer agents allows us to override the intrinsic properties of an azobenzene species by triggering the reverse isomerization direction (Z → E) by the same wavelength of light, which normally triggers E → Z isomerization. The behavior we report appears to be general, implying that the metastable isomer of a photoswitch can be isomerized to the more stable one catalytically upon reduction, permitting the optimization of azobenzene switching in new as well as indirect ways.
First use of p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor having tunable selectivity towards cross azo-compounds by trapping silver ions
Sarkar, Piyali,Mukhopadhyay, Chhanda
supporting information, p. 442 - 451 (2016/01/30)
p-tert-Butylcalix[4]arene-tetra-O-acetate was established for the first time as a member of the nanoreactor series, even without having any -OH group. The nano range distribution of this nanoreactor was ascertained by DLS, SEM and TEM studies. The capability of this cavitand towards hosting amines in a competitive manner generates a new green pathway for cross coupling of aromatic amines to give the corresponding azo-compounds. In this context, using p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor and silver nitrate as a catalyst, we got the cross azo-compound in good to excellent yields in the eco-friendly solvent water. This green methodology is also applicable for the synthesis of respective homo-compounds.
Palladium-Catalyzed Oxidative Synthesis of Unsymmetrical Azophenols
Nguyen, Thi Hong Long,Gigant, Nicolas,Delarue-Cochin, Sandrine,Joseph, Delphine
, p. 1850 - 1857 (2016/03/15)
A straightforward palladium-catalyzed oxidative hydroxylation of azobenzenes is reported. The developed methodology tolerates various functional groups and allows the synthesis of diverse unsymmetrical azophenols under mild conditions in good to excellent yields. A complementary procedure was also investigated by in situ generation of PIFA. This study represents the first general method for the synthesis of o-hydroxyazobenzenes starting from simple azoarenes.
AgNO3 as nitrogen source for rhodium(III)-catalyzed synthesis of 2-aryl-2H -benzotriazoles from azobenzenes
Li, Jixing,Zhou, Hui,Zhang, Jinlong,Yang, Huameng,Jiang, Gaoxi
supporting information, p. 9589 - 9592 (2016/08/01)
A new approach has been established for Rh(iii)-catalyzed direct aza oxidative cyclization of non-prefunctionalized azobenzenes to provide 2-aryl-2H-benzotriazoles in good yields, in which AgNO3 instead of conventional azide reagents for the first time functions as the nitrogen source for the nitrogenation reaction. Preliminary mechanistic studies suggest that the Rh(iii)-catalyst could account for the nitration reaction, and subsequently cationic silver species might both play a vital role in the fission of the nitrogen-oxygen bonds in nitro groups and promote aza oxidative cyclization.
Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes
Geng, Xiaoyu,Wang, Congyang
supporting information, p. 2434 - 2437 (2015/05/27)
The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the first time, the acetate-acceleration effect is showcased in Re-catalyzed C-H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which is in sharp contrast to those of previous Rh- and Co-systems. (Chemical Presented).
Palladium-Catalyzed sp2 C-H Arylation of Azoarenes with Arylhydrazines
Li, Mingyang,Ye, Yong
, p. 4137 - 4142 (2015/12/26)
Transition-metal-catalyzed direct functionalization of C-H bonds is important for new compound synthesis, but usually needs special reagents and harsh conditions. With the aid of an azo directing group, the palladium-catalyzed ortho-sp2 C-H bond activation of azoarenes with hydrazines has been explored. In the reaction, the Pd catalyst reacts with azobenzene to form a palladacyclic intermediate, which reacts with a phenyl radical generated from phenylhydrazine under heating and oxygen to produce a PdIV or PdIII intermediate. This finally undergoes reductive elimination to give the ortho-arylated products with the release of the PdII catalyst. This reaction provides a novel access to ortho-aryl azoarenes under mild conditions in high yield. Helpful hydrazines: With the aid of an azo directing group, the palladium-catalyzed ortho-sp2 C-H bond activation of azoarenes with hydrazines has been explored. The catalyst reacts with azobenzene to form a palladacyclic intermediate, which reacts with a phenyl radical generated from phenylhydrazine produce a PdIV or PdIII intermediate. This undergoes reductive elimination to give the ortho-arylated products and regenerate the catalyst. This reaction provides a novel access to ortho-aryl azoarenes under mild conditions in high yield.
Palladium-catalyzed ortho-functionalization of azoarenes with aryl acylperoxides
Qian, Cheng,Lin, Dongen,Deng, Yuanfu,Zhang, Xiao-Qi,Jiang, Huanfeng,Miao, Guang,Tang, Xihao,Zeng, Wei
, p. 5866 - 5875 (2014/08/05)
With the aid of an azo directing group, Pd-catalyzed ortho-sp2 C-H bond activation/functionalization of azoarenes with aryl acyl peroxides has been explored. This transformation provides easy access to regioselectively introducing acyloxyl and aryl groups into azoarenes by simply changing the reaction temperature and solvent. This journal is the Partner Organisations 2014.
