Camphor Sulfonimine Compounds: Bottom-Up Design of MOFs from Organic Frameworks Based on X-rays and DFT-D3

Abstract

DFT-D3 calculations based on structural X-ray diffraction data obtained for 3-oxo-camphorsulfonyl imine (1), camphorsulfonyl chloride (2) and seven camphor sulfonimines (O2SNC10H13NR, L1−L7), from which L2 (R=4-OHC6H4), L4 (R=4-ClC6H4) and L6 (R=3,5-(CH3)2C6H3) are synthesized and characterized in this work, provide information into the intra- and inter-molecular interactions with concomitant elucidation of the supramolecular arrangement of the compounds. The DFT-D3 calculations performed in small clusters of two or three molecular units reproduce the interactions observed via X-ray analyses, showing that, as a general trend, the structural arrangement of the molecules is driven by electronic rather than by packing parameters. In all compounds, the self-assembly of 3D structures involves the sulfonyl imine group (-NSO2) either to establish hydrogen bonds through oxygen atoms or non-classic oxygen–aliphatic hydrogen or non-bonding interactions (NBIs), which also involve sulfonyl oxygen atoms. Interestingly, the camphor sulfonimine compounds (L2, L3), having protic groups (R=C6H4X:X=OH, L2 or X=NH2, L3) at the aromatic imine substituents (=NR), present an extra π-π stacking, which is absent in the other compounds’ aromatic derivatives. The X-ray analysis shows that all the reported camphor sulfonimine compounds display the E configuration with respect to the imine substituent (R). The study of the redox behavior of the compounds by cyclic voltammetry enables insight into the solution properties of the compounds and the rationalization of the molecular interactions that stand in the solid and solution states. Camphor sulfonimine compounds (L) display appropriate binding atoms to coordinate transition metals. The results herein show that monodentate coordination through the nitrogen atom of the sulfonimine five-membered ring to the {Ag(NO3)} metal center is favored. When this imine nitrogen atom is not itself involved in the organic framework, DFT-D3 calculations show that the complexation does not affect the non-covalent interactions that are reproduced in the MOF structure.