The Molecular Complexes of Monoalkylammonium Bromide Salts with (R)-(+)-1,1′-Bi-2-Naphthol and Rac-1,1′-Bi-2-Naphthol

Abstract

The crystal structures of hexyltrimethylammonium bromide (6TAB) adduct of (R)-(+)-1,1′-bi-2-naphthol (RBNP) and decyltrimethylammonium bromide (10TAB) adduct of rac-1,1′-bi-2-naphthol (BNP) have been determined by the X-ray diffraction method. The molecules of the 6TAB/RBNP complex are held in their aggregates by O1…Br [3.228(4)Å], O2…Br [3.225(6)Å] intermolecular hydrogen bonds and C-H…π interactions between the alkyl chain, methyl groups and aromatic rings of the naphthol moieties. It was observed in the crystal structure of 10TAB adduct of BNP that the crystal structure formation was mainly stabilized by the intermolecular hydrogen bonds between the bromide anion and OH group of BNP (01…Brl [3.241(4)Å], O2…Br2 [3.172(3)Å]). In both complexes, the packing arrangement of the monoalkylammonium bromide salts with non-planar aromatic molecules are different from those observed in complexes of monoalkylammonium bromide salts with planar aromatic guest molecules. X-ray powder diffraction studies on both complexes showed that the crystals complex can be obtained by crystallization from solution and also by mixing powdered samples in a mortar. This study has shown that a non-chiral host amphiphile can form a complex with either a chiral or racemic aromatic guest compound.