Are They Connected? Liquid-State NMR Spectroscopy of Chitinous Materials

Since the resurgence of interest in chitinous materials in the 1970s, significant efforts have been devoted to their utilization and valorization. With the availability of ISO 13485-certified chitinous materials suitable for biomedical use, these polymers are no longer merely waste-derived byproducts. Chemical derivatization has resulted in a large and diverse body of literature on chitinous-based materials. Nevertheless, the reproducibility of reported results remains a persistent challenge, often arising from inadequate structural and compositional characterization. To address this limitation and to facilitate unambiguous structure-property correlations, this review proposes a first set of minimum NMR reporting standards, illustrated through practical examples. In addition, it provides guidance on the effective use of classical liquid-state NMR techniques, such as ¹H, ¹³C, ¹H-¹H COSY, ¹H-¹³C HSQC, HMBC and H2BC, as well as emerging diffusion-based methods for the characterization of unknown chitinous materials and their derivatives.