Spectra solid-state

Water of crystallation (solid state spectra) 3600-3100 (w) Usually a weak band at 1640-1615 cm also. Water in trace amounts in KBr disks shows a broad band at 3450 cm k... 

Aldehydes —CHO (See also Table 7.49 for C—H.) All values given below are lowered in liquid-film or solid-state spectra by about 10-20 cm Vapor-phase spectra have values raised about 20 cm Saturated 1740-1720 ... 

It was already suggested in the early investigations that the differences between the chemical properties of aminopyrimidines and anilines might result from tautomerism see, for example, reference 319. The early infrared studies on the solid-state spectra of these... 

The tautoraerism of certain difunctional derivatives of l-thia-3,4-diazole has received considerable attention. Pala assigned structure 156 to 2,5-dimercapto-l-thia-3,4-diazole on the basis of infrared spectral data, and Thorn" reached the same conclusion by comparing its ultraviolet spectrum (measured in ethanol) with those of the four possible methylated derivatives. However, the infrared spectrum of a chloroform solution of the parent compound showed bands at 2600-2550 cm indicating an SH group and the probable occurrence of form 157 under these conditions, and this conclusion is supported by the occurrence of SH bands in solid state spectra obtained by Swiss investigators. For a summary of earlier work on these compounds, see reference 187. 

The substituted five-ring OPVs have been processed into poly crystal line thin films by vacuum deposition onto a substrate from the vapor phase. Optical absorption and photolumincscence of the films are significantly different from dilute solution spectra, which indicates that intermolecular interactions play an important role in the solid-state spectra. The molecular orientation and crystal domain size can be increased by thermal annealing of the films. This control of the microstruc-ture is essential for the use of such films in photonic devices. 

The chemical shifts are for the solid state spectra obtained by the CP-MAS technique and referred to hexamethyl benzene (132.3 ppm compared to TMS). 

The conclusion that solid-state spectra provide evidence for a lignin-carbohydrate complex is of special interest. Solid-state spectra of lignin fractions obtained by ball milling and extraction with dimethyl sulfoxide exhibit carbohydrate signals and vice... 

Recent reports 54 seem to indicate that the resolution of the notoriously difficult solid-state spectra of coals may be enhanced by such techniques as double exponential multiplication and convolution difference. Differential relaxation behaviour as discussed in connection with intermolecular effects in carbohydrates and low temperature methods may further improve identification. 

It has been shown that fairly quantitative solid-state spectra can be obtained for coals. With other polymers our experience indicates the same behaviour. Only in the case of highly polar groups, e.g. carbonyl and carboxyl groups, may difficulties be noted. 

The deuteron solid state spectra are completely dominated by the quadrupole coupling of the deuteron I = 1 spin, the NMR frequency being given by lS)... 

The purpose of this article is to discuss conformational shift variations in some selected solid state spectra on the basis of discrete rotational isomeric states and to compare them with molecular packing effects. 

Fig. 3a and b. Fast exchange-slow exchange NMR transition for the conformational interconversion of octamethyltetrasiloxane. a, MAS 13C-NMR solid state spectra on the left side in comparison to solution spectra in propane-di on the right side (at 75.47 MHz), b. MAS 29Si-NMR spectra at 59.63 MHz. Temperatures are indicated in K, shift positions refer to TMS = 0 ppm and correspond to the scale at the bottom. (Ref. I0))... 

Figure 5 shows a conformational model of OMTS for discussion the solid state spectra. At the left a tilted crown type conformation is shown, where the carbons oc-... 

In the 1970s the structure and dynamics of lipid bilayer membranes were extensively investigated by NMR. The principles of the NMR spectroscopy applied to the study of biomembranes are reviewed in Ref. 5, together with the fruitful achievements in the early stage. In the 1980s the NMR biomembrane research was carried out mainly by applying the solid-state NMR techniques [6-11]. Generally, the solid-state spectra are of low reso-... 

Fig. 9 Solid-state spectra of bromide complexes with TCP (solid lines) 1 Pr4N+[Br", (TCP)4], 2 (Et4N+)2[(Br )2,(TCP)3], 3 Bu4N+ [Br, (TCP)4]. Note spectra of the corresponding complexes in solution are shown as gray dashed line [23]...

Generally, however, linewidths in solid state spectra are grater than in solution. An example is shown in Fig. 48, which compares the solution spectrum (a above) of a bisphosphonate (the structure of which is shown in the Figure) with that in the solid state (b below). While the lines are much sharper in the upper spectrum, we can clearly see splittings in the solid state spectrum. Since the protons are decoupled, these must be due not to coupling but to nonequivalence. In the solid state the molecule becomes unsymmetrical due to... 

We have referred to the various interactions which can cause line broadening in the solid state. One of these, which is normally not a problem in liquid state NMR, is due to the fact that the chemical shift itself is a tensor, i.e. in a coordinate system with orthogonal axes x, y and z its values along these axes can be very different. This anisotropy of the chemical shift is proportional to the magnetic field of the spectrometer (one reason why ultra-high field spectrometers are not so useful), and can lead in solid state spectra to the presence of a series of spinning sidebands, as shown in the spectra of solid polycrystalline powdered triphenylphosphine which follows (Fig. 49). In the absence of spinning, the linewidth of this sample would be around 75 ppm ... 

The anisotropies that lead to line broadening in isotropic ESR spectra influence solid-state spectra more directly. Accordingly a more complex spin Hamiltonian is required to interpret such spectra ... 

Far less effort has been directed at organic solid-state spectra than at organo-metallics and coordination complexes. Much of the work on organic systems was done by Walter Gordy and his students at Duke University in the 1960s and 1970s. We review a couple of these experiments here. More information is available in Gordy s book.30... 

The same general considerations apply to nonazo pigments. Attempts have been made to theoretically interpret absorption spectra of polycylic compounds by quantum mechanics. These studies compared the absorption of systems such as indigo [1] with known spectra of polymethine dyes. However, the investigation of solid state spectra is aggravated by interactions within the crystal lattice and has rarely been studied. 

Considering the fact that pigments exist as crystals dispersed in the application media, these studies are only of theoretical value. However, it has been shown that the maximum specific extinction of Pigment Red 112 is independent of whether it is measured in solution or in crystalline form. The study compared transmission spectra of the dissolved pigment with the solid-state spectra of crystals in a transparent film. 

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