Copper-Mediated Trifluoromethylation of Benzylic Csp3 -H Bonds.

Trifluoromethyl-containing compounds play a significant role in medicinal chemistry, materials and fine chemistry. Although direct C-H trifluoromethylation has been achieved on Csp2 -H bonds, direct conversion of Csp3 -H bonds to Csp3 -CF3 remains challenging. We report herein an efficient protocol for the selective trifluoromethylation of benzylic C-H bonds. This process is mediated by a combination CuIII -CF3 species and persulfate salts. A wide range of methylarenes can be selectively trifluoromethylated at the benzylic positions. A combination of experimental and theoretical mechanistic studies suggests that the reaction involves a radical intermediate and a CuIII -CF3 species as the CF3 transfer reagent.

Tuning Gold Nanoparticles with Chelating Ligands for Highly Efficient Electrocatalytic CO2 Reduction.

Capped chelating organic molecules are presented as a design principle for tuning heterogeneous nanoparticles for electrochemical catalysis. Gold nanoparticles (AuNPs) functionalized with a chelating tetradentate porphyrin ligand show a 110-fold enhancement compared to the oleylamine-coated AuNP in current density for electrochemical reduction of CO2 to CO in water at an overpotential of 340 mV with Faradaic efficiencies (FEs) of 93 %. These catalysts also show excellent stability without deactivation (<5 % productivity loss) within 72 hours of electrolysis. DFT calculation results further confirm the chelation effect in stabilizing molecule/NP interface and tailoring catalytic activity. This general approach is thus anticipated to be complementary to current NP catalyst design approaches.

Two-fold 2D + 2D → 2D interweaved rhombus (4,4) grid: synthesis, structure, and dye removal properties in darkness and in daylight.

Compound [Cu(NI-mbpy-44)2(NO3)2]·4H2O (1, NI-mbpy-44 = N-(pyridin-4-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide) adopting a two-dimensional (2D) periodical rhombus (4,4) grid has been synthesized. This grid doubly interweaves in a parallel fashion to result in overall 2D + 2D → 2D networks with approximately 14% sufficient free volumes in which lattice H2O molecules reside. Dye removal studies show that 1 selectively adsorbs anionic methyl orange (MO) and acid orange 7 (AO7) over cationic methylene blue (MB) and malachite green (MG) from aqueous solutions containing single or mixed dyes in darkness at room temperature. The experimental isotherm data were analyzed using linear Langmuir and Freundlich isotherm equations; the results indicated that the Langmuir model showed a better fit for the adsorption of MO and AO7 over 1, with high dark adsorption capacities of 810 and 370 mg g-1, respectively, although there could also be other associated mechanisms. The dark adsorption kinetics of MO and AO7 over 1 obeyed the pseudo-second-order kinetic model. Electrostatic attraction appears to be the dominating mechanism for adsorptive removal of MO and AO7 by 1, whereas π-π stacking (MO and AO7) and hydrogen-bonding interactions (AO7) could also be responsible. Exploration of the adsorption performance of MO and AO7, including studying the kinetics in daylight, shows similar results to those obtained in darkness, indicating the negligible influence of daylight on the dye removal. Nevertheless, 1 could liberate NI-mbpy-44 and Cu(ii) into water throughout the entire adsorption experiment, which could be a potential environmental hazard, this could cause secondary pollution and mean that 1 is impractical for use as an adsorbent candidate.