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.