Sensitive chemoselectivity of cellulose nanocrystal films

Abstract

Cellulose nanocrystals (CNCs), self-assembled into a chiral nematic structure film, create an advanced platform for the fabrication of remarkable sensing, photonic and chiral nematic materials. Despite extensive progress in the knowledge of functions of CNCs, their chemoselectivity has rarely been reported. Here, we report a brand-new perspective of CNCs in chemoselectivity, which shows sensitive selectivity even between isomers of monosaccharides and disaccharides by generating discernible crystal patterns. This sensitive selectivity of glucose homologs is attributed to the selective carbohydrate–carbohydrate interactions (CCIs) through generating hydrogen bonds between CNC units and the glucose homologs, endowing a remarkable color variation of the CNC films. Moreover, the CCIs are distinct for different immersion times and concentrations of glucose homologs, verified through Fourier Transform Infrared Spectroscopy (FTIR) spectra. Based on the sensitive CCIs, pristine CNC films are then used as templates to generate chiral mesoporous carbon films with tunable specific surface areas by assembly of CNC suspensions and the glucose homologs. We envision that the sensitive chemoselectivity of CNC films as well as precise structure modulation could provide insights into the recognition of carbohydrates and the preparation of mesoporous carbon in numerous practical applications. A pristine chiral nematic cellulose nanocrystal film with sensitive chemoselectivity to glucose homologues and even isomers of monosaccharides and disaccharide are prepared through self-assembly. For different kinds of glucose homologs, distinct crystal morphologies are formed due to the selective carbohydrate–carbohydrate interactions. Besides, the highly ordered left-helical layered structure of pristine cellulose nanocrystal film could be used as templates for the precise construction of delicate nanostructures.