Complex Formation of Aromatic Compounds Containing an Hetero Ring

3 Complex Formation of Aromatic Compounds Containing an Hetero Ring [54] 

In the previous section, only the complexes comprising aromatic compounds without hetero rings were analysed. A variety of aromatic compounds with a hetero ring also form complexes with cationic surfactants. In this section, five kinds of complex crystal structures are discussed. 

1 Crystal structures of X (CTAB-acridine), XI (CTAB-phenoxazine) and XII (CTAB-phenothiazine) 

The crystal structure of X is isomorphous to crystals II and III. Since the occupancy factor of the acridine molecule is 0.5, there is one acridine molecule, on average, in the two unit cells along the c-axis. Although there is no hydrogen bond between acridine and the bromide anion, the intermolecular distances suggest the presence of a weak C-H... Br contact. The hydrophilic ribbon comprises the bromide anion and trimethylammonium cation, and the hydrophobic ribbon comprises the alkyl group and acridine. The ribbons are packed alternately to define a planar sheet parallel to the ac-plane. The crystal structures of XI and XII are isostructural to X, with the same pattern of occupancy of the heteroaromatic rings. 

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