Anion assisted conformationally guided self-assemblies of multi-component cocrystals of dioxime

Abstract

Multi-component cocrystals of 1,3-benzenedialdoxime (H₂BNAD) with tetrabutylammonium salts provide examples of dendrimer-like anion assisted assemblies. The assembly of the multi-component cocrystal comprised of H₂BNAD and tetrabutylammonium fluoride has dendrimer-like packing. It possesses dimeric cyclic sub-assemblies of dioximes and monomeric dioxime molecules to which fluoride ions act as connectors. Chloride ions act as connectors to three dioxime molecules in a dendrimer-like assembly of a multi-component cocrystal of H₂BNAD with tetrabutylammonium chloride. In this assembly water molecules are held in the interstices by hydrogen bonding interactions with host oximes. The assembly forms cyclic ensembles in such a way as to accommodate the tetrabutylammonium cations. The cocrystal of H₂BNAD comprised of tetrabutylammonium cations and HBNAD⁻ possesses dimeric hydrogen bonded cyclic sub-assemblies of neutral H₂BNAD and HBNAD⁻ connected to each other in a chain-like structure. In general, two conformers of H₂BNAD originating from different orientations of the oxime functional groups across the phenylene ring are key factors in providing directionality to the self-assemblies. Single crystal X-ray structure determination and Raman spectroscopy were used to ascertain signatures of the H₂BNAD conformers present in these assemblies.