NMR spectra of PF1-1 Floridan palygorskite strongly suggest that Al3+ occurs only in octahedral coordination. X-ray microanalysis of the palygorskite fibers indicate a chemical composition defined by the atomic ratios: Mg/Si = 0.34, Al/Si = 0.27, and Fe/Si = 0.04. Considering the NMR and CEC data in this report along with the previously published results of IR and Mössbauer spectroscopic studies, the following structural formula is proposed for PF1-1 palygorskite:

$${\rm{(M{g_{2.12}}A{l_{1.68}}F{e^{3 + }}_{0.24}{\square _{0.96}})S{i_8}{O_{20}}{(OH)_2}{(O{H_2})_4}}}$$

Dynamic nuclear polarization (DNP) is a technique in magic-angle spinning (MAS) nuclear magnetic resonance (NMR) which leads to sensitivity enhancement and helps to overcome the issue of low polarization in detected nuclei. Recent research showed, that methyl groups, which show active reorientation dynamics and cause heteronuclear cross relaxation at typical DNP temperatures around 100 K, may be used as a pinpoint source of polarization for selective and site-specific probing. In this study, we investigated the cross-relaxation behavior of methyl groups in nicotine and caffeine under DNP. These effects could be useful for investigating receptor/ligand binding.

The intercalation of the cationic surfactant cetyltrimethylammonium (C16TMA) into the interlayer of an acid-activated clay in the presence of different anions has been studied in detail. When Br or OH anions were used, the basal spacing increased significantly, the increase being related to the loading concentration of the surfactant solution. For intercalated compounds prepared from the hydroxide form, the basal spacing at room temperature varied from 1.6 to 3.8 nm. However, for organoclays prepared from the surfactant bromide, the basal spacing is almost loading- independent (1.9 nm). The use of hydroxide and bromide at higher pH is crucial to intercalating larger amounts of C16TMA cations and, hence, to improving the exfoliation of the silicate sheets. Magic-angle spinning 13C nuclear magnetic resonance spectroscopy indicates that the intercalated surfactants exhibit a significant degree of gauche conformation. According to in situ powder X-ray diffraction, an increase of the basal spacing to 4.08 nm is observed at intermediate temperatures of 50 to 150°C for organoclay with an initial basal spacing of 3.7 nm. At higher temperatures, decomposition of the surfactant occurs and the basal spacing decreases to ~1.4 nm.