99-27-4Relevant articles and documents
Multi-Stimuli-Responsive Directional Assembly of an Amphiphilic Donor–Acceptor Alternating Supramolecular Copolymer
Chakraborty, Saptarshi,Ray, Debes,Aswal, Vinod K.,Ghosh, Suhrit
, p. 16379 - 16387 (2018)
The stimuli-responsive supramolecular co-assembly of two π-amphiphiles, NDI-1 and Py-1, in which an acceptor (A) (naphthalene diimide) and a donor (D) (pyrene) chromophore, respectively, serve as the hydrophobic segment, is described. In addition, both contain an amide group in a designated location so that H-bonding and D–A charge-transfer (CT) interactions can operate simultaneously. H-bonding among the amide groups not only enhanced the CT interaction promoted by the alternating D–A stacking propensity, but also fixed the lateral orientation of the two chromophores and thus compelled the anionic and nonionic hydrophilic head groups, appended with the D and A amphiphiles, respectively, to remain segregated on two opposite sides of the amphiphilic alternating supramolecular copolymer. This copolymer showed spontaneous polymersome assembly with the D-appended anionic groups displayed at the outer surface, whereas the A-appended hydrophilic wedge converged at the inner lacuna. In contrast, spherical or cylindrical micellar structures were produced by Py-1 and NDI-1, respectively. Effective functional-group display in the D–A supramolecular polymersome enabled protein-surface recognition and inhibition of the enzymatic activity of Cht. Under a reducing environment, formation of NDI.? jeopardized the D–A interaction and thus the A chromophores were ejected out of the membrane of the polymersome causing its gradual contraction in size by >75 %. D–A supramolecular polymersomes also exhibited a lower critical solution temperature that could be tuned across a temperature window of 40 to 70 °C by varying the ratio of the A and D components in the alternating supramolecular copolymer.
Chemoselective Hydrogenation of Nitroarenes Catalyzed by Molybdenum Sulphide Clusters
Pedrajas, Elena,Sorribes, Iván,Gushchin, Artem L.,Laricheva, Yuliya A.,Junge, Kathrin,Beller, Matthias,Llusar, Rosa
, p. 1128 - 1134 (2017/03/27)
Herein, we describe an atom efficient and general protocol for the chemoselective hydrogenation of nitroarenes to anilines catalyzed by well-defined diimino and diamino cubane-type Mo3S4 clusters. The novel diimino [Mo3S4Cl3(dnbpy)3]+ ([5]+) (dnbpy=4,4′-dinonyl-2,2′-dipyridyl, L1) trinuclear complex was synthesized in high yields by simple ligand substitution reactions starting from the thiourea (tu) [Mo3S4(tu)8(H2O)]Cl4?4 H2O (3) precursor. This strategy has also been successfully adapted for the isolation of the diamino [Mo3S4Cl3(dmen)3](BF4) ([6](BF4)), (dmen=N,N′-dimethylethylenediamine) salt. Applying these catalysts, high selectivity in the hydrogenation of functionalized nitroarenes has been accomplished. Over thirty anilines bearing synthetically functional groups have been synthesized in 70 to 99 % yield. Notably, the integrity of the cluster core is preserved during catalysis. Based on kinetic studies on the hydrogenation of nitrobenzene and other potential reaction intermediates, the direct reduction to aniline is the preferential route.
Ni@Pd core-shell nanoparticles supported on a metal-organic framework as highly efficient catalysts for nitroarenes reduction
Jian, Siping,Li, Yingwei
, p. 91 - 97 (2016/01/12)
Ni@Pd core-shell nanoparticles with a mean particle size of 8-9 nm were prepared by solvothermal reduction of bivalent nickel and palladium in oleylamine and trioctylphosphine. Subsequently, the first-ever deposition of Ni@Pd core-shell nanoparticles having different compositions on a metal-organic framework (MIL-101) was accomplished by wet impregnation in n-hexane. The Ni@Pd/MIL-101 materials were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy and also investigated as catalysts for the hydrogenation of nitrobenzene under mild reaction conditions. At 30 °C and 0.1 MPa of H2 pressure, the Ni@Pd/MIL-101 gives a TOF as high as 375 h-1 for the hydrogenation of nitrobenzene and is applicable to a wide range of substituted nitroarenes. The exceptional performance of this catalyst is believed to result from the significant Ni-Pd interaction in the core-shell structure, together with promotion of the conversions of aromatics by uncoordinated Lewis acidic Cr sites on the MIL-101 support.
