Correlation of adsorbed and embedded palladium species in chitosan composite nanofibers with their catalytic activities for Suzuki reactions

Study on the relationship of catalytic activities and o‐Ps annihilation properties of supported palladium species chelated by different functional groups

“…Interestingly, it is reported that o ‐Ps can react with metal ions and then lowering the likelihood of o ‐Ps annihilation. [ 21 ] In our previous study, [ 22 ] we also found that the intensity ( I 3 ) decreased with the increase of the content of Pd 2+ cations adsorbed or embedded in the chitosan composite nanofibers, indicating the o ‐Ps annihilation by Pd 2+ cations. Moreover, due to the different surrounding environments, the embedded and adsorbed Pd 2+ cations exhibited distinct o ‐Ps annihilation properties.…”

“…Moreover, due to the different surrounding environments, the embedded and adsorbed Pd 2+ cations exhibited distinct o-Ps annihilation properties. On the basis of the above studies, [21,22] we have speculated that the o-Ps could be used as the probe to determine the annihilation properties of Pd 2+ cations in different local environments, which then could be associated with their catalytic activities. The effectiveness of ligands or chelating groups on catalytic activities of palladium catalysts can then be eventually resolved.…”

Palladium Supported on Bioinspired Materials as Catalysts for C–C Coupling Reactions

“…The final Pd@CS/PMAA nanofibers were applied as catalyst in the Mizoroki-Heck cross-coupling: working with 0.54 mol% of Pd loading, the reaction of aryl iodides with terminal alkenes afforded products with complete trans-stereoselectivity and 62-98% yields after 3-10 h; moreover, good recyclability of the catalyst was also testified, up to ten cycles without loss of activity (Scheme 48). Very recently, Qi et al proposed a small modification in the preparation of palladium catalysts embedded in chitosan/poly(methacrylic acid) composite nanofibers: that is, the use of a small amount of PEO as a further co-spinning agent, in order to improve both chemical and mechanical properties of the final Pd@CS/PMAA/PEO nanofibers [126].…”

“…Catalysts 2023, 13, x 45 of 62 Scheme 48. Mizoroki-Heck coupling of aryl iodides with terminal alkenes promoted by palladium catalyst supported on chitosan/poly(methacrylic acid) composite nanofibers (Pd@CS/PMAA), reported in 2022 by Qi et al [126].…”

A PPh3 modified-chitosan supported Pd nanocatalyst for heterogeneous Suzuki–Miyaura cross coupling reactions

“…22 Chitosan (CS) is composed of linear polysaccharides and its abundant NH 2 and OH groups enable it to act as a suitable ligand for immobilization and stabilization of Pd metal. In recent years, the modified-chitosans [23][24][25][26] and composite materials of chitosan with Fe 3 O 4 [27][28][29][30][31] carbon nanotubes, 32 MOFs 33 and nanofibers 34 have been reported for the heterogeneous Suzuki-Miyaura coupling reactions.…”