Novel cellulose acetate grafted poly(NHC complex) as an efficient and robust catalyst for CuAAC and ketone reduction

Developing robust and biobased heterogeneous catalysts remains a major challenge in sustainable chemistry. In this work, cellulose triacetate (CTA), an organically soluble polysaccharide derivative, was combined with N-heterocyclic carbene (NHC) ligands to design a new family of CTA-supported Cu-NHC catalysts. A series of polymerizable N-vinylimidazolium salts was synthesized by N-quaternization of 1-vinylimidazole and subsequently copolymerized with CTA via AIBN-initiated free-radical polymerization to afford CTA-grafted polyimidazolium salts serving as NHC precursors. Deprotonation with tBuOK followed by CuBr coordination yielded the corresponding Cu-NHC complexes, denoted CTA-g-[(NHC)CuBrR]. The synthesized materials were thoroughly characterized by FTIR, NMR, TGA, XRD, UV-Vis spectroscopy, CHN elemental analysis, zeta potential measurements, and ICP analysis. The resulting Cu-NHC complexes exhibited excellent catalytic activity in Huisgen [3 + 2] cycloaddition and ketone hydrosilylation reactions, as well as remarkable thermal and structural stability. Most importantly, they retained high catalytic performance over five consecutive recycling runs in click reactions. These findings demonstrate the potential of CTA-supported Cu-NHC complexes as efficient, recyclable, and sustainable biobased catalysts.