Fabrication of uniform Pd nanoparticles immobilized on crosslinked ionic chitosan support as a super-active catalyst toward regioselective synthesis of pyrazole-fused heterocycles

• Published in: International journal of biological macromolecules 2023-12, Vol.253, p.126589-126589, Article 126589
• Main Authors: Elyasi, Zahra, Ghomi, Javad Safaei, Najafi, Gholam Reza, Sharif, Mahboubeh A.
• Format: Article
• Language: English
• Subjects: biodegradability; biopolymers; Chitosan; copolymerization; crosslinking; heterocyclic compounds; Heterogeneous nanocatalyst; ionic liquids; nanocatalysts; nanoparticles; palladium; Pd nanoparticles; Poly ionic liquid; porosity; raw materials; Regioselective synthesis; regioselectivity; surface area; thermal stability; ultrasonics; weight loss
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2023.126589

Selection of biodegradable chitosan as a raw material is a smart technique due to its easy modifiability and high renewability. Herein, taking advantage of these functional characteristics, an ionic biopolymer support is produced from copolymerization of allylated chitosan (with 48 % degree of substitution) and polymerizable ionic liquid ([MEVIm]Br). Next, palladium nanoparticles are successfully stabilized in this designed support through a facile manner based on interconnected porous network, ionic nature and rich functional groups. Then, the Pd@CS-PIL structure was utilized as a heterogeneous catalyst for regioselective synthesis of pyrazole-fused heterocycles. The as-synthesized Pd@CS-PIL was characterized by various techniques such as XRD, EDX, FESEM, elemental mapping, TEM, BET, ICP, TGA, and FT-IR to better determine the structure, morphology, purity and physical properties. The obtained results revealed that the proposed nanostructure provides favorable porosity with significant specific surface area (139.2 m2.g−1), Pd nanoparticles with high dispersion (mean diameter ∼ 22.8 nm) and crosslinked nature with good thermal stability (50 % weight loss about 600 °C). Therefore, Pd@CS-PIL nanostructure showed the key features of a super-active catalyst, and pharmaceutical pyrazole-fused scaffolds were produced in favorable yields (86–96 %) under ultrasound conditions. [Display omitted] •A new and professional ionic chitosan-based support was introduced.•Pd@CS-PIL was fabricated as a novel bifunctional heterogeneous nanocatalyst.•The catalytic performance was evaluated in regioselective construction of pharmaceutical pyrazole-fused heterocycles.