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Organo-modified layered materials characterization poses challenges due to their complexity and how other aspects such as contamination, preparation methods and degree of intercalation influence the properties of these materials. Consequently, a deep understanding of their interlayer organization is of utmost importance to optimize their applications. These materials can in fact improve the stability of photoactive molecules through intercalation, avoiding the quenching of their emission at the solid state, to facilitate their use in sensors or other devices. Two synthetic methods for the preparation of saponites with a cationic surfactant (CTABr) and a neutral chromophore (Fluorene) were tested and the obtained products were initially characterized with several complementary techniques (XRPD, SEM, TGA, IR, UV-Vis, Fluorescence and Raman spectroscopy), but a clear understanding of the organization of the guest molecules in the material could not be obtained by these techniques alone. This information was obtained only by thermogravimetry coupled with gas chromatography and mass spectroscopy (TGA-GC-MS) which allowed identifying the species present in the sample and the kind of interaction with the host by distinguishing between intercalated and adsorbed on the surface. [ABSTRACT FROM AUTHOR]

The heating process (30–200 °C) of a palygorskite-indigo mixture has been monitored in situ and simultaneously by synchrotron powder diffraction and Raman spectroscopy. During this process, the dye and the clay interact to form Maya blue (MB), a pigment highly resistant to degradation. It is shown that the formation of a very stable pigment occurs in the 70–130 °C interval; i.e., when palygorskite starts to loose zeolitic water, and is accompanied by a reduction of the crystallographic a parameter, as well as by alterations in the C=C and C=O bonds of indigo. Mid- and near-infrared spectroscopic work and microporosity measurements, employed to study the rehydration process after the complex formation, provide evidence for the inhibition of the rehydration of MB as compared with palygorskite. These results are consistent with the blocking of the palygorskite tunnel entrance by indigo molecules with a possible partial penetration inside the tunnels. The surface silanols of palygorskite are not perturbed by indigo, suggesting that MB is not a surface complex. [ABSTRACT FROM AUTHOR]

X-ray powder diffraction played a key role in materials science over the past 25 years. It is now possible to employ powder diffraction at in situ conditions to study solid-state transformations. “Real” materials science samples often show deviations from the “perfectly crystalline” state and hence powder diffraction reaches its limits. Spectroscopic techniques can often provide useful complementary information. With the aim of gaining information from this aspect, we combined Raman spectroscopy with diffraction. A novel experimental setup for simultaneous in situ Raman and XRPD experiments was designed and realized at the SNBL line at ESRF Synchrotron (Grenoble-F). High-resolution XRPD data can be collected with a time resolution in the range of minutes. A permanently installed Raman spectrometer can now be used to measure the same sample at the same spot under the same conditions. A wide variety of non-ambient conditions are available. The setup is described with limitations and potentialities, by describing one example of application. Finally some hints on future improvements are described. [ABSTRACT FROM AUTHOR]

Materials containing disordered moieties and/or amorphous or liquid-like phases or showing surface- or defect-related phenomena constitute a problem with respect to their characterization using X-ray powder diffraction (XRPD), and in many cases Raman spectroscopy can provide useful complementary information. A novel experimental setup has been designed and realized for simultaneous in situ Raman/high-resolution XRPD experiments, to take full advantage of the complementarities of the two techniques in investigating solid-state transformations under non-ambient conditions. The added value of the proposed experiment is the perfect synchronization of the two probes with the reaction coordinate and the elimination of possible bias caused by different sample holders and conditioning modes used in ` in situ but separate' approaches. The setup was tested on three solid-state transformations: (i) the kinetics of the fluorene–TCNQ solid-state synthesis, (ii) the thermal swelling and degradation of stearate–hydrotalcite, and (iii) the photoinduced (2 + 2)-cyclization of ( E)-furylidenoxindole. These experiments demonstrated that, even though the simultaneous Raman/XRPD experiment is more challenging than separate procedures, high-resolution XRPD and Raman data can be collected. A gas blower allows studies from room temperature to 700 K, and 100 K can be reached using a nitrogen cryostream. The flexibility of the experimental setup allows the addition of ancillary devices, such as a UV lamp used to study photoreactivity. [ABSTRACT FROM AUTHOR]

Low-ordered carbon/layered double hydroxide (LDH) nanocomposites were prepared by rehydration of the oxides produced by calcination of an organic LDH. While the memory effect is a widely recognized effect on oxides produced by inorganic LDH, it is unprecedented from the calcination/rehydration of organic ones. Different temperatures (400, 600, and 1100 °C) were tested on the basis of thermogravimetric data. Water, instead of a carbonate solution, was used for the rehydration, with CO2 available from water itself and/or air to induce a slower process with an easier and better intercalation of the carbonaceous species. The samples were characterized by X-ray powder diffraction (XRPD), infrared in reflection mode (IR), and Raman spectroscopies and scanning electron microscopy (SEM). XRPD indicated the presence of carbonate LDH, and of residuals of unreacted oxides. IR confirmed that the prevailing anion is carbonate, coming from the water used for the rehydration and/or air. Raman data indicated the presence of low-ordered carbonaceous species moieties and SEM and XRPD the absence of separated bulky graphitic sheets, suggesting an intimate mixing of the low ordered carbonaceous phase with reconstructed LDH. Organic LDH gave better memory effect after calcination at 400 °C. Conversely, the carbonaceous species are observed after rehydration of the sample calcined at 600 °C with a reduced memory effect, demonstrating the interference of the carbonaceous phase with LDH reconstruction and the bonding with LDH layers to form a low-ordered carbon/LDH nanocomposite. [ABSTRACT FROM AUTHOR]