Ionic liquid decorated chitosan hybridized with clay: A novel support for immobilizing Pd nanoparticles.

Taking advantage of biocompatible chitosan (CS), halloysite (Hal) and ionic liquid (IL), a triple hybrid system, Hal-CS-SFIL was designed and prepared via covalent bonding of Cl-functionalized Hal and CS-SFIL. The hybrid system was successfully utilized as a heterogeneous catalyst support for immobilizing Pd nanoparticles. The resulting hybrid catalyst, Pd@Hal-CS-SFIL was used as a heterogeneous catalyst for catalyzing Sonogashira reaction under mild reaction condition. The results showed that this catalyst was efficient. Studying the recyclability of the catalyst confirmed that the catalyst could be recycled for seven reaction runs with slight loss of the catalytic activity and Pd leaching. The role of each hybrid component in the catalysis was confirmed by comparing the catalytic activity of Pd@Hal, Pd@CS, Pd@Hal-CS and Pd@Hal-CS-SFIL. Moreover, the synergism between the components was established by observing the superior catalytic activity of the catalyst with those of Pd@Hal-CS + SFIL, Pd@CS-SFIL+Hal and Pd@Hal + CS-SFIL.