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Catalytic Asymmetric Friedel–Crafts Reactions of Nitroalkenes
Published in Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera, Catalytic Asymmetric Reactions of Conjugated Nitroalkenes, 2020
Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera
Song et al. reported an asymmetric Friedel–Crafts alkylation of indoles 2 with nitroalkenes 1 in the presence of 5 mol% of cationic chiral NCN pincer Pt(II) aquo complex C5 along with bis-(imidazolinyl)phenyl (Phebim) ligand. The products, nitroalkylated indoles 3, were obtained in high yields with good enantioselectivities (up to 83% ee, Scheme 5.13).32
Effects of Calcium and Chloride Ions in Iron Ore Reverse Cationic Flotation: Fundamental Studies
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Deisiane Ferreira Lelis, Daniel Geraldo da Cruz, Rosa Malena Fernandes Lima
In the spectra of hematite conditioned with CaCl2 and without a reagent (Figure 10), a band is found at 1654 cm−1, which may arise from a shift in the H–O–H bending vibrations from water between 1630 and 1600 cm−1 (Nakamoto 1978), as well as the neutral aquo-complex [Fe(H2O)(OH)2] and the chloro-complex [Fe(H2O)22+Cl−]+ + OH−. A new absorption band at 1465 cm−1 appears for the hematite conditioned with CaCl2, possibly from the chloro-complex [Fe(H2O)22+Cl−]+ + OH− on the hematite surface. However, the decrease in the recovery of hematite conditioned with CaCl2 (Figure 2) may be related to the physical adsorption (via electrostatic attraction) of Ca2+ ions (~1.8 × 10−3 M) on the negatively charged hematite surface at pH 10.5. This adsorption, plus the positively charged iron chloro-complexes on the hematite surface, would prevent aminium ion adsorption, the main adsorption mechanism of which is via electrostatic attraction to negatively charged sites on the mineral surface (Churaev et al. 2000; Kou, Tao and Xu 2010; Smith and Scott 1990).
Nitric oxide release from a photoactive water-soluble ruthenium nitrosyl. Biological effects
Published in Journal of Coordination Chemistry, 2018
Meredith A. Crisalli, Lilian P. Franco, Bruno R. Silva, Alda K. M. Holanda, Lusiane M. Bendhack, Roberto S. Da Silva, Peter C. Ford
The ΦNO values for 1 at acidic pH are consistent with that (5 × 10−3) reported previously for the aquo complex [Ru(salen)(H2O)(NO)]Cl (4) in aqueous solution when irradiated at 365 nm [10b]. However, both are surprisingly less photolabile than is the simpler, but water-insoluble, salen complex Ru(salen)(NO)Cl (5, salen = N,N’-ethylenebis(salicylideneiminato)) when irradiated in acetonitrile at 365 nm (ΦNO = 0.13 ± 0.01) [8b]. We do not have a ready explanation for the > 20-fold lower quantum yields for NO release from 1 and 4 in buffered aqueous media than from 5 in acetonitrile, unless the solvent H2O somehow accelerates nonradiative deactivation of the responsible excited state(s). Lehnert and coworkers [26] noted a similar decrease in NO photolability of several other ruthenium nitrosyl complexes in aqueous solution and pointed out that such decreases might affect the biological efficacy. The quantum yield for NO release for photolysis carried out at 470 nm with a blue LED is even smaller (ΦNO = 0.2 × 10−3 in pH 7.4 buffered solution, SI Figure S1).
High performance {Nb5TaX12}@PVP (X = Cl, Br) cluster-based nanocomposites coatings for solar glazing applications
Published in Science and Technology of Advanced Materials, 2022
Clément Lebastard, Maxence Wilmet, Stéphane Cordier, Clothilde Comby-Zerbino, Luke MacAleese, Philippe Dugourd, Naoki Ohashi, Tetsuo Uchikoshi, Fabien Grasset
Distilled water and acetone were selected as the dispersing media to obtain stable and transparent solutions. The optical absorption of the K4[{Nb5TaXi12}Xa6] (X = Cl, Br) cluster compounds and the [{Nb5TaCli12}Cla2(H2O)a4]∙4 H2O aquo-complex dispersed in water and acetone solvents are reported in Figures S5 and S6, respectively. For K4[{Nb5TaCli12}Cla6], the main absorption peak in the UV region is located at 388 nm in water and 416 nm in acetone. In the NIR region, a large peak at 873 nm is observed for water (with a small shoulder at lower energy ≈650 nm), whereas acetone presents peaks at higher wavelengths, one at 993 nm and a large peak shoulder around 1300 nm. As already demonstrated for Ta6 and Nb6 clusters [45,50], this behavior clearly indicated the chemical instability of the reduced {Nb5TaCli12}2+ cluster cores in acetone in the presence of oxygen and its oxidation into {Nb5TaCli12}3+/4+ cluster cores (VEC = 14 or 15) during the dissolution process of K4[{Nb5TaCli12}Cla6] in oxygenated acetone media. Similar results were obtained for K4[{Nb5TaBri12}Bra6], nevertheless the optical properties are less interesting due to a stronger absorption in the visible range. Regarding the [{Nb5TaCli12}Cla2(H2O)a4]∙4 H2O aquo-complexes, after solubilization in water, the UV-Vis-NIR spectrum presents superimposable bands with the corresponding precursors K4[{Nb5TaXi12}Xa6] (X = Cl, Br) cluster compounds dispersed in water, so it was inferred that the solutions contain the same species, i.e. [{Nb5TaXi12}(H2O)a6]2+ cluster units with a VEC = 16 (Figure S5).