A novel approach to characterization of a relatively unstable intercalation compound under ambient conditions:...

Characteristics of a kaolinite-acetone intercalation compound prepared using a kaolinite N-methylformamide intercalation compound (Kaol-NMF) as an intermediate were obtained by a set of techniques with attention to suppressing evaporation and deintercalation of acetone. X-ray diffraction (XRD) with spectroscopic analyses, Fourier-transform infrared spectroscopy (FTIR) accompanied by solid-state ¹³C and ²⁹Si nuclear magnetic resonance (NMR) spectroscopy with cross polarization (CP) and magic angle spinning (MAS) enable us to demonstrate full replacement of a pre-intercalated NMF monolayer with an acetone monolayer between the layers of kaolinite with an increase in the basal spacing from 1.08 nm (Kaol-NMF) to 1.12 nm. In addition, the appearance of an additional OH stretching band at 3630 cm^-1 and the shift of the C[double bond, length as m-dash]O stretching band to a lower wavenumber, from 1714 to 1701 cm^-1, in the FTIR spectrum, along with a downfield shift of the signal due to C[double bond, length as m-dash]O groups from 209 ppm, where a singlet was observed in the liquid-state ¹³C NMR spectrum of acetone in CDCl₃, to 219 ppm in the ¹³C CP/MAS NMR spectrum, indicate hydrogen bond formation between interlayer hydroxyl groups of kaolinite and C[double bond, length as m-dash]O groups of the intercalated acetone molecules. These careful characterization studies provide information on an interaction between kaolinite and acetone under ambient conditions.