Chitosan as capping agent in a robust one-pot procedure for a magnetic catalyst synthesis

Tomer A Dickstein; Ergang Zhou; Kian K Hershberger; Angela K Haskell; David Gene Morgan; Maren Pink; Barry D Stein; Linda Zh Nikoshvili; Valentina G Matveeva; Lyudmila M Bronstein

doi:10.1016/j.carbpol.2021.118267

Chitosan as capping agent in a robust one-pot procedure for a magnetic catalyst synthesis

Carbohydr Polym. 2021 Oct 1:269:118267. doi: 10.1016/j.carbpol.2021.118267. Epub 2021 May 31.

Affiliations

¹ Indiana University, Department of Chemistry, 800 E. Kirkwood Av., Bloomington, IN 47408, USA.
² Indiana University, Department of Biology, 1001 E. Third St., Bloomington, IN 47405, USA.
³ Tver State Technical University, Department of Biotechnology, Chemistry, and Standardization, A.Nikitin str., 22, 170026 Tver, Russian Federation.
⁴ Tver State Technical University, Department of Biotechnology, Chemistry, and Standardization, A.Nikitin str., 22, 170026 Tver, Russian Federation; Tver State University, Regional Technological Centre, Zhelyabova str., 33, 170100 Tver, Russian Federation.
⁵ Indiana University, Department of Chemistry, 800 E. Kirkwood Av., Bloomington, IN 47408, USA; A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov St., Moscow 119991, Russian Federation; King Abdulaziz University, Faculty of Science, Department of Physics, Jeddah 21589, Saudi Arabia. Electronic address: lybronst@indiana.edu.

PMID: 34294299
DOI: 10.1016/j.carbpol.2021.118267

Abstract

Here, we report a one-pot solvothermal method for the development of magnetically recoverable catalysts with Ru or Ag nanoparticles (NPs) capped by chitosan (CS), a derivative of natural chitin. The formation of iron oxide NPs was carried out in situ in the presence of CS and iron acetylacetonate in boiling triethyleneglycol (TEG) due to CS solubilization in warm TEG. Coordination with Ru or Ag species and the NP formation take place in the same reaction solution, eliminating intermediate steps. In optimal conditions the method developed allows stabilization of 2.2 nm monodisperse Ru NPs (containing both Ru⁰ and Ru⁴⁺ species) that are evenly distributed through the catalyst, while for Ag NPs, this stabilizing medium is inferior, leading to exceptionally large Ag nanocrystals. Catalytic testing of CS-Ru magnetically recoverable catalysts in the reduction of 4-nitrophenol to 4-aminophenol with excess NaBH₄ revealed that the catalyst with 2.2 nm Ru NPs exhibits the highest catalytic activity compared to samples with larger Ru NPs (2.9-3.2 nm). Moreover, this catalyst displayed extraordinary shelf-life in the aqueous solution (up to ten months) and excellent reusability in ten consecutive reactions with easy magnetic separation at each step which were assigned to its conformational rigidity at a constant pH. These characteristics as well as favorable environmental factors of the catalyst fabrication, make it promising for nitroarene reduction.

Keywords: Chitosan; Magnetically recoverable catalysts; Nanoparticles; Nitrophenol reduction; Ruthenium.