Abstract
Abstract: The limited access to fast and facile general analytical methods for cellulosic and/or biocomposite materials currently stands as one of the main barriers for the progress of these disciplines. To that end, a diverse set of narrow analytical techniques are typically employed that often are time-consuming, costly, and/or not necessarily available on a daily basis for practitioners. Herein, we rigorously demonstrate a general quantitative NMR spectroscopic method for structural determination of crystalline cellulose samples. Our method relies on the use of a readily accessible ionic liquid electrolyte, tetrabutylphosphonium acetate ([P4444][OAc]):DMSO-d6, for the direct dissolution of biopolymeric samples. We utilize a series of model compounds and apply now classical (nitroxyl-radical and periodate) oxidation reactions to cellulose samples, to allow for accurate resonance assignment, using 2D NMR. Quantitative heteronuclear single quantum correlation (HSQC) was applied in the analysis of key samples to assess its applicability as a high-resolution technique for following cellulose surface modification. Quantitation using HSQC was possible, but only after applying T2 correction to integral values. The comprehensive signal assignment of the diverse set of cellulosic species in this study constitutes a blueprint for the direct quantitative structural elucidation of crystalline lignocellulosic, in general, readily available solution-state NMR spectroscopy. Graphic abstract: [Figure not available: see fulltext.]
Original language | English |
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Pages (from-to) | 7929-7953 |
Journal | Cellulose |
Volume | 27 |
Issue number | 14 |
DOIs | |
Publication status | Published - 1 Sept 2020 |
MoE publication type | A1 Journal article-refereed |
Funding
Open access funding provided by University of Helsinki including Helsinki University Central Hospital. The authors would like to thank the Academy of Finland for funding under the project ‘WTF-Click-Nano’ (Project #: 311255).
Keywords
- Cellulose dissolution
- Ionic liquid
- Nitroxyl radical
- Periodate
- Quantitative HSQC
- TEMPO