Crystalline structure characterization methods

Recently the pyridine adduct of borabenzene 5 has been synthesized as a yellow crystalline solid (26). Its structural characterization by X-ray methods provides the first structural data of an uncomplexed borabenzene... 

It is shown that electrolytic manganese dioxide, which has been obtained from fluorine-containing electrolytes differs from traditional types of Mn02 obtained by state-of-the-art synthesis methods. This material is characterized by the increased amount of structural defects. It is shown that crystalline structure with a large number of defects has a higher catalytic and electrochemical activity. 

Protonated polymethylbenzenes281 and the chlorohexamethylbenzenium cation,282 intermediates in aromatic electrophilic substitutions known as Wheland intermediates, have been isolated as crystalline salts, allowing investigators to obtain their X-ray crystal structure. Nitrosoarenium a complexes of various arenes were directly observed by transient absorption spectroscopy.283 Kochi presented a method combining appropriate instrumental techniques (X-ray crystallography, NMR, time-resolved UV-vis spectroscopy) for the observation, identification, and structural characterization of reactive intermediates fa and n complexes) in electrophilic aromatic substitution.284... 

The metal oxides prepared by conventional baking or by the CVD method are, in general, chemically stable, crystalline materials, and show excellent mechanical, electrical, optical, and physical properties. Flexible porous gel films obtained by the surface sol-gel process are totally different. In this chapter, we described a new preparative method for ultrathin metal oxide films by stepwise adsorption of various metal alkoxides. We named this method the surface sol-gel process. Structural characterization of the gel films thus obtained, the electrical property, and formation of nano-composites with organic compounds, were also explained. The soft porous gel contains many active hydroxyl groups at the surface and interior of the film. This facilitates adsorption of organic compounds, and consequent preparation of ultrathin metal oxide/polymer nano-composite films and organization of functional small molecules. In the nano-composites, proper selection of polymer components leads to the design of new materials with unique electrical, optical, and chemi-... 

The crystalline structure of cellulose has been characterized by X-ray diffraction analysis and by methods based on the absorption of polarized infrared radiation. The unit cell of native cellulose (cellulose I) consists of four glucose residues (Figs. 3-6 and 3-7). In the chain direction (c), the repeating unit is a cellobiose residue (1.03 nm), and every glucose residue is accordingly displaced 180° with respect to its neighbors, giving cellulose a... 

In addition to identifying and characterizing known crystalline phases, single crystal, and more recently, powder diffraction methods can be used to determine the atomic positions within the crystal structures of new and uncharacterized materials. An excellent demonstration of how XRD structure determination methods can be applied in concert with other characterization techniques for... 

The driving force behind the rapid development of powder diffraction methods over the past 10 years is the increasing need for structural characterization of materials that are only available as powders. Examples are zeolite catalysts, magnets, metal hydrides, ceramics, battery and fuel cell electrodes, piezo- and ferroelectrics, and more recently pharmaceuticals and organic and molecular materials as well as biominerals. The emergence of nanoscience as an interdisciplinary research area will further increase the need for powder diffraction, pair-distribution function (PDF) analysis of powder diffraction pattern allows the refinement of structural models regardless of the crystalline quality of the sample and is therefore a very powerful structural characterization tool for nanomaterials and disordered complex materials. 

Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and infrared spectroscopy are the common techniques used in the characterization of the structure of the congealed solid. Thermal analytic methods, such as DSC and differential microcalorimetric analysis (DMA), are routinely used to determine the effect of solutes, solvents, and other additives on the thermomechanical properties of polymers such as glass transition temperature (Tg) and melting point. The X-ray diffraction method is used to detect the crystalline structure of solids. The infrared technique is powerful in detecting interactions, such as complexation, reaction, and hydrogen bonding, in both the solid and solution states. 

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