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Carboxylated Chitosan Nanocrystals: Novel Synthetic Route and Application as Superior Support for Gold-Catalyzed Reactions

preprint
submitted on 23.01.2020, 14:10 and posted on 24.01.2020, 11:24 by Tony Jin, Davis Kurdyla, Sabahudin Hrapovic, Alfred Leung, Sophie Régnier, Yali Liu, Audrey Moores, Edmond Lam

Chitin nanocrystals (ChNCs) were prepared by partial cleavage of glycosidic bonds in chitin with concurrent oxidation of chitin C6 primary alcohols to produce carboxylate groups on the surface of the ChNCs. Following alkaline deacetylation of the ChNCs in the presence of NaBH4 to inhibit “end-peeling” afforded chitosan nanocrystals (ChsNCs) with a degree of deacetylation (DDA) >80%. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform Infrared (FTIR) spectroscopy were used to determine the morphology and composition of these carboxylated ChNCs and ChsNCs. Subsequently, two methods were used to deposit Au onto the nanocrystals, and the catalytic activities of the resulting biomass-based nanocatalysts were tested for the 4-nitrophenol reduction and the aldehyde-amine-alkyne (A3) coupling reaction. In particular, Au nanoparticles over ChsNCs featured the highest turnover frequency value for the 4-nitrophenol reduction reported to date. Spectroscopic and imaging techniques confirmed the importance of controlling precisely the redox state of Au as it is being deposited to afford highly disperse active site on the bio-nano-support.

Funding

Natural Science and Engineering Research Council of Canada (NSERC) Discovery Grant - Discovery Accelerator Supplement

Canada Foundation for Innovation

National Research Council (NRC) New Beginnings Initiative Ideation fund

Centre in Green Chemistry and Catalysis (CGCC)

Fonds de Recherche du Québec – Nature et technologies

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National Research Council Canada

McGill University

History

Email Address of Submitting Author

audrey.moores@gmail.com

Institution

McGill University

Country

Canada

ORCID For Submitting Author

0000-0003-1259-913X

Declaration of Conflict of Interest

We have no conflict of interest to declare

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