Carbamoyl-Decorated Cyclodextrins for Carbon Dioxide Adsorption

Advances in materials science and technology have prompted researchers to look to nature for new high-performance, low-cost materials. Among these, cyclodextrins have been widely used as a material in industrial applications. Inspired by previous work by our research group that led to the functionalization of cucurbit[6]uryl and its conversion into supramolecular nanospheres with good CO2 adsorption capacity, this work aims to improve the ability of cyclodextrins to capture CO2 by functionalizing them with amide groups. Carbon dioxide adsorption experiments on functionalized cyclodextrins showed an adsorption capacity similar to that of BEA zeolite, a material currently used in the industry for gas adsorption. Moreover, these adsorption properties could also be exploited to improve the adsorption capacity of drugs, a field in which cyclodextrins are widely used. The new cyclodextrin molecules were characterized by nuclear magnetic resonance spectroscopy and mass spectrometry, thanks to which we could determine the degree of functionalization of the new macrocycles. In addition, using Fourier-transform infrared spectroscopy, we demonstrated the presence and interaction of carbon dioxide adsorbed by the material, whereas an in silico study confirmed the chemisorption as the principal adsorption process, as experimentally inferred using the pseudo-second-order (PSO) kinetic model.