Intercalation of Nitroanilines into Kaolinite and Second Harmonic Generation

Kaolinite intercalates ortho - and para -nitroanilines ( o NA and p NA) between the layers whereas meta- nitroaniline ( m NA) is not intercalated. para- Nitroaniline takes a monolayer arrangement with the long axis inclined to the layers of kaolinite. o NA molecules also take a monolayer arrangement though the orientation is not well ordered. Kaolinite− p NA and − o NA intercalation compounds exhibit second harmonic generation, which is evaluated quantitatively by the second-harmonic wave generated with evanescent wave (SHEW) method. This indicates noncentrosymmetric arrangements of p NA and o NA, and such orientations are induced by the asymmetric environment of the interlayer region of kaolinite.