24567-97-3Relevant articles and documents
Suspending Ion Electrocatalysts in Charged Metal–Organic Frameworks to Improve the Conductivity and Selectivity in Electroorganic Synthesis
Guo, Wei-Wei,Zhang, Chi,Ye, Ji-Jie,Liu, Zi-Kun,Chen, Kai,Wu, Chuan-De
supporting information, p. 3627 - 3634 (2019/07/31)
Electroorganic synthesis is an environmentally friendly alternative to traditional synthetic methods; however, the application of this strategy is heavily hindered by low product selectivity. Metal–organic frameworks (MOFs) exhibit high selectivity in numerous catalytic reactions; however, poor conductivity heavily limits the application of MOFs in electroorganic synthesis. To realize the electrocatalytic application of MOFs in selective electroorganic synthesis, a practically applicable strategy by suspending ion electrocatalysts in charged MOFs is herein reported. This approach could markedly improve the product selectivity in electroorganic synthesis. In the electrocatalytic oxidative self-coupling of benzylamine experiments, the imine product selectivity is markedly improved from 61.3 to 94.9 %, when the MOF-based electrocatalyst is used instead of the corresponding homogeneous electrocatalyst under the identical conditions. Therefore, this work opens a new route to improve the product selectivity in electroorganic synthesis.
Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water
Bardelang, David,Casano, Gilles,Poulhs, Florent,Karoui, Hakim,Filippini, Jessica,Rockenbauer, Antal,Rosas, Roselyne,Monnier, Valrie,Siri, Didier,Gaudel-Siri, Anouk,Ouari, Olivier,Tordo, Paul
supporting information, p. 17570 - 17577 (2015/02/19)
The flexible tetranitroxide 4T has been prepared and was shown to exhibit a nine line EPR spectrum in water, characteristic of significant through space spin exchange (Jij) between four electron spins interacting with four nitrogen nuclei (Jij aN). Addition of CB[8] to 4T decreases dramatically all the Jij couplings, and the nine line spectrum is replaced by the characteristic three line spectrum of a mononitroxide. The supramolecular association between 4T and CB[8] involves a highly cooperative asymmetric complexation by two CB[8] (K1 = 4027 M-1; K2 = 202 800 M-1; α = 201) leading to a rigid complex with remote nitroxide moieties. The remarkable enhancement for the affinity of the second CB[8] corresponds to an allosteric interaction energy of ≈13 kJ mol-1, which is comparable to that of the binding of oxygen by hemoglobin. These results are confirmed by competition and reduction experiments, DFT and molecular dynamics calculations, mass spectrometry, and liquid state NMR of the corresponding reduced complex bearing hydroxylamine moieties. This study shows that suitably designed molecules can generate allosteric complexation with CB[8]. The molecule must (i) carry several recognizable groups for CB[8] and (ii) be folded so that the first binding event reorganizes the molecule (unfold) for a better subsequent recognition. The presence of accessible protonable amines and H-bond donors to fit with the second point are also further stabilizing groups of CB[8] complexation. In these conditions, the spin exchange coupling between four radicals has been efficiently and finely tuned and the resulting allosteric complexation induced a dramatic stabilization enhancement of the included paramagnetic moieties in highly reducing conditions through the formation of the supramolecular 4T@CB[8]2 complex.
