N-Hydroxysuccinimide-activated esters as a functionalization agent for amino cellulose: synthesis and solid-state NMR characterization
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We propose a mild and versatile synthesis protocol based on N-hydroxysuccinimide-activated esters for the introduction of new functionalities to cellulose, using as starting point established protocols for the tosylation of cellulose and its subsequent reaction with a diamine linker. As a proof of concept, we describe the functionalization of microcrystalline cellulose with a N-hydroxysuccinimide-activated ester of benzophenone, a photoreactive functional group. Irradiation of the final product with UV light yields a self-standing polymer film and is expected to result in cross-linking among cellulose chains. To monitor structural changes at the molecular level, each functionalization step is characterized by a multinuclear solid-state NMR approach. DNP-enhanced 15N CP MAS NMR experiments reveal the formation of the amide bond to the photoreactive linker and deliver further information about the binding situation of nitrogen-containing groups in these materials. The flexible synthesis protocol described here can be easily extended to a broad range of other functionalities of interest, both for the cellulose and macromolecular research.
KeywordsSolid-state NMR Dynamic nuclear polarization Functionalization
This work has been supported by the Project iNAPO by the Hessen State Ministry of Higher Education, Research and the Arts and intramural funding in the FIPRE consortium. GB and TG thank the DFG under contract Bu 911/26-1 for financial support.
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