Water soluble polymer–surfactant complexes-stabilized Pd(0) nanocatalysts: Characterization and structure–activity relationships in biphasic hydrogenation of alkenes and α,β-unsaturated ketones

• Supramolecular self-assemblies developed for the synthesis of Pd nanoparticles.
• The physico-chemical properties were modulated with polymer–surfactant assemblies.
• Selective hydrogenation of α,β-unsaturated ketones was obtained in water.
• Higher TOFs were achieved using surfactant-rich mixtures.
• Correlation of the zeta-potential values with the catalytic activities was demonstrated.

A suitable approach to stabilize palladium nanoparticles in water as a green reaction medium for catalytic hydrogenation reactions is described. Supramolecular self-assemblies, obtained through the mixture of modified polyethyleneimines as amphiphilic polymers and water-soluble ammonium salts as surfactants, were used as efficient protective agents in the synthesis of Pd(0) nanospecies. The size and dispersion of the nanoparticles prepared with these original self-assemblies were characterized by TEM, SAXS and DLS techniques. The performances of the catalysts according to the polymer–surfactant mixtures were investigated in the hydrogenation of alkenes and α,β-unsaturated ketones in pure biphasic water/substrate medium, under mild conditions (room temperature and 1 bar H2). The nanocatalysts showed efficient catalytic activities and selectivity towards CC bonds. From investigations, the polymer–surfactant complexes act as cooperative protective agents and a pertinent structure–activity relationship was proposed based on the zeta-potential values and the catalytic activity of the resulting colloids.

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