Lipidic Mesophase-Embedded Palladium Nanoparticles: Synthesis and Tunable Catalysts in Suzuki–Miyaura Cross-Coupling Reactions

Abstract

Lipidic cubic phases (LCPs) can reduce Pd2+ salts to palladium nanoparticles (PdNPs) of ∼5 nm size in their confined water channels under mild conditions. The resulting PdNP-containing LCPs were used as nanoreactor scaffolds to catalyze Suzuki–Miyaura cross-coupling reactions in the aqueous channels of the mesophase. To turn on catalysis, PdNP-containing LCPs were activated by swelling the aqueous channels of the lipidic framework, thereby enabling diffusion of the water-soluble substrates to the catalysts. The mesophases play a threefold role: they act as reducing agents for Pd2+, as limiting templates for their growth, and as support. The system was characterized and investigated by small-angle X-ray scattering (SAXS), cryo-transmission electron microscopy, dynamic light scattering, and nuclear magnetic resonance. Bulk LCPs and three dispersed palladium/lipid hybrid nanoparticle types were applied in the catalysis. The latterliposomes, hexosomes, and cubosomescan be obtained by design through combination of lipids and additives. The Suzuki–Miyaura cross-coupling of 5-iodo-2′-deoxyuridine and phenylboronic acid was used as a model reaction to study these systems. Bulk Pd-LCPs deliver the Suzuki–Miyaura product in 24 h in conversions up to 98% at room temperature, whereas with palladium/lipid dispersions at 40 °C, 68% of the starting material was transformed to the product after 72 h.

New Amphiphilic Imidazolium/Benzimidazolium Calix[4]arene Derivatives: Synthesis, Aggregation Behavior and Decoration of DPPC Vesicles for Suzuki Coupling in Aqueous Media

“…Recently, phospholipid vesicles were successfully used as both effective stabilizers for Pd(0) nanoparticles and microreactors for Suzuki–Miyaura coupling in aqueous media [ 44 ]. To the best of our knowledge, vesicles doped by amphiphilic NHC metal complexes and their application for the catalysis are not presented in literature.…”

Lipid Nanoparticles─From Liposomes to mRNA Vaccine Delivery, a Landscape of Research Diversity and Advancement

“…In another example, stable palladium nanoparticles with sizes between 1–3 nm were prepared by reduction of a palladium precursor within liposomal nanoreactors using glycerol as both the reducing agent and stabilizer . Palladium nanoparticles ∼5 nm in diameter were prepared in the aqueous mesophase channels of lipidic cubic phases by reduction of Pd 2+ salts and used as supported catalysts for Suzuki–Miyaura cross-coupling reactions . Similar methods using nanoreactors have been used for the synthesis of nonmetallic nanoparticles.…”

“…242 Palladium nanoparticles ∼5 nm in diameter were prepared in the aqueous mesophase channels of lipidic cubic phases by reduction of Pd 2+ salts and used as supported catalysts for Suzuki−Miyaura cross-coupling reactions. 243 Similar methods using nanoreactors have been used for the synthesis of nonmetallic nanoparticles. For example, monodisperse nanocrystals of CdS, ZnCdS, and HgCdS have been synthesized in the cores of liposomes, using them as nanoreactors for precipitation or crystallization.…”

What Vibrational Spectroscopy Tells about Water Structure at the Electrified Palladium–Water Interface

“…Pd or Pt metal finds many applications in heterogeneous catalysis. − The application of massive Pd in electrocatalysis is hindered by hydrogen absorption and Pd hydrides formation. This limitation is removed when a thin film of Pd is deposited on a gold surface.…”