The hexadecyltrimethylammonium chloride inclusion complex with rac-1,1 '-bi-2-naphthol

The crystal structure of 1:1 inclusion complex of hexadecyltrimethylammonium chloride (16TAC) with rac-1,1'-bi-2-naphthol (BNP) [a = 47.968(2), b = 8.757(2), c = 18.249(2)Angstrom, beta = 100.772(6)degrees, C2/c, R = 0.075 for 2578 observed reflections] was determined by the X-ray diffraction method. In the crystal structure there is a strong hydrogen bond between one of the OH groups of BNP and the oxygen of water molecule (O1 ... OW, 2.665(3)Angstrom). The chloride anion acts as the hydrogen acceptor of the OH group of the water molecule (OW ... Cl-, 3.105(3)Angstrom), and of the second OH group of BNP (O2 ... Cl-, 3.108(2)Angstrom). The short C-H ... C distances between hydrogen atoms of the alkyl carbon atom together with one of the methyl groups, and carbon atoms in one of the naphthol rings indicated an existence of C-H ...pi interactions. The hydrophobic long alkyl chain of the 16TAC molecule contributes to the unique molecular packing arrangement observed in the 16TAC/BNP complex. The alkyl chain of the 16TAC molecule in this crystal is bent at C10 and does not exhibit the complete zig-zag planes as reported on the 16TAC crystal. The BNP molecules are completely trapped between the 16TAC molecules, and the interdigitated arrangement of the 16TAC molecules are clearly observed in the ac-plane. The X-ray powder diffraction studies on the mixed powdered samples of 16TAC and BNP suggested that the complex can be obtained by crystallization from the solution and also by mixing powdered samples in a mortar.