Structure elucidation of a complex CO2-based organic framework material by NMR crystallography

• Published in: Chemical science (Cambridge) 2016-01, Vol.7 (7), p.4379-4390
• Main Authors: Leclaire, Julien, Poisson, Guillaume, Ziarelli, Fabio, Pepe, Gerard, Fotiadu, Frédéric, Paruzzo, Federico M, Rossini, Aaron J, Dumez, Jean-Nicolas, Elena-Herrmann, Bénédicte, Emsley, Lyndon
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Cristallography
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c5sc03810c

A three-dimensional structural model of a complex CO2-based organic framework made from high molecular weight, self-assembled, flexible and multi-functional oligomeric constituents has been determined de novo by solid-state NMR including DNP-enhanced experiments. The complete assignment of the N-15, C-13 and H-1 resonances was obtained from a series of two-dimensional through space and through bond correlation experiments. MM-QM calculations were used to generate different model structures for the material which were then evaluated by comparing multiple experimental and calculated NMR parameters. Both NMR and powder X-ray diffraction were evaluated as tools to determine the packing by crystal modelling, and at the level of structural modelling used here PXRD was found not to be a useful complement. The structure determined reveals a highly optimised H-bonding network that explains the unusual selectivity of the self-assembly process which generates the material. The NMR crystallography approach used here should be applicable for the structure determination of other complex solid materials.