Study of the effect of the ligand structure on the catalytic activity of Pd@ ligand decorated halloysite: Combination of experimental and computational studies

Abstract

Taking advantage of computational chemistry, the best diamine for the synthesis of a multi‐dentate ligand from the reaction with 3‐(trimethoxysilyl) propylisocyanate (TEPI) was selected. Actually, predictive Density Functional Theory (DFT) calculations provided the right diamino chain, i.e. ethylenediamine, capable to sequester a palladium atom, together with the relatively polar solvent toluene, and then undergo the experiments as a selective catalytic agent. The ligand was then prepared and applied for the decoration of the halloysite (Hal) outer surface to furnish an efficient support for the immobilization of Pd nanoparticles. The resulting catalyst exhibited high catalytic activity for hydrogenation of nitroarenes. Moreover, it showed high selectivity towards nitro functional group. The study of the catalyst recyclability confirmed that the catalyst could be recycled for several reaction runs with only slight loss of the catalytic activity and Pd leaching. Hot filtration test also proved the heterogeneous nature of the catalysis.

Phenoxylation of Alkynes through Mono‐ and Dual Activation Using Group 11 (Cu, Ag, Au) Catalysts

“…NCI plots computed by the NCIPLOT package, confirmed the significant additional non‐covalent interactions due to the aromatic rings of the IPr* ligand, whereas only the ones between the phenoxide and one of the aryl rings on the diphenylacetylene for the IMe based system (see Figure ). The plot for the IPr ligand is placed in between, and it confirms the effect of the substitution of phenyl by methyl groups, with much less favourable π‐π staking interactions . Thus, NCI plots and EDA analyses here unveil why the sterically more hindered IPr* ligand ends up showing less unfavourable kinetics and thermodynamics than expected for the C–O bond formation.…”

Can Heteroarenes/Arenes Be Hydrogenated Over Catalytic Pd/C Under Ambient Conditions?

“…[21] In a recent study of palladium nanoparticles, highly active and selective hydrogenation of nitro group within nitroarenes was achieved using Pd@Hal/di-urea. [22] Functional groups possessing unsaturated bonds, such as esters, amides, and N=C-N bonds (ex: guanidine, which is known for Y-aromaticity [23] ), proved to be resilient to reduction. In addition, hydroxyl groups at positions other than benzyl remained, as shown in the reaction of 3-(pyridin-2-yl)prop-2-yn-1-ol, which could be quantitatively hydrogenated in this work, although we previously reported that use of 500 mol% Pd/C led to a moderate yield of 57 %.…”

“…In contrast, previous studies on dearomatic hydrogenation method of quinoline utilizing palladium nanoparticles reported selective hydrogenation on the ring containing nitrogen . In a recent study of palladium nanoparticles, highly active and selective hydrogenation of nitro group within nitroarenes was achieved using Pd@Hal/di‐urea . Functional groups possessing unsaturated bonds, such as esters, amides, and N=C‐N bonds (ex: guanidine, which is known for Y‐aromaticity), proved to be resilient to reduction.…”

Pd on magnetic hybrid of halloysite and POSS‐containing copolymer: An efficient catalyst for dye reduction

“…[ 9–11 ] The increasing growth of Hal is due to its tunability and also capability to be incorporated in composites and hybrids. [ 12–15 ]…”

“…In the pursuit of our inquiries on the chemistry and usage of Hal, [ 14,32–37 ] herein, we wish to describe synthesis and application of a new magnetic composite of Hal and polymer for catalytic dye degradation. The target composite was covalent and fabricated through reaction of vinyl‐functionalized magnetic Hal with hydroxyethyl methacrylate (HEMA) and methacrylate polyhedral oligomeric silsesquioxane (POSS).…”