IR spectra of the polycrystalline samples of D PAM, dispersed in the KBr pellets, measured at two diferent temperatures and in the N_H and N_D ranges. found, no general diferentiation of the polarization properties of the two opposite spectral branches of the N_H band occurs. Therefore, the PAM crystal spectra in regard to these properties fairly resemble significantly the spectra of N methylthioacet amide and acetanilide crystals measured earlier. In Figure 6 IR spectra of polycrystalline samples of PAM, N methylthio acetamide, and acetanilide, measured in the frequency range of the N_H band, are shown. 3. 4. Isotopic Dilution Effects in the Crystalline Spectra. Replacement of protons by deuterons in the hydrogen bonds of PAM crystals causes the appearance of a new band in the 2300_2500 cm range, attributed to the N_D bond stretching N_D ).

In Figure 7 IR spectra of partially deuterated polycrystalline samples of PAM, measured in the vibrations the ac plane, 60% D PAM and 40% PAM, the ab plane, 60% D PAM and 40% PAM. vector of the incident beam of the IR radiation with respect to the oriented crystal lattice. The observed homogeneous linear dichroic properties of the crystalline spectra LY294002 in the N_D band range prove that the band consists of only one spectral branch. It remains in an approximate relation by the 2 factor with the frequency of the higher frequency branch of the residual N_H band. Next the almost homogeneous polarization properties of the residual N_H band were also measured. The shape of the band remained practically unchanged in spite of the replacement of the major part of the hydrogen bond protons by deuterons.

The residual N_H bands of the two crystal forms remain unchanged while the correspond ing bands of the isotopically Maraviroc neat crystals difer to some extent. 4. 1. Choice of Model forthe Spectra Interpretation. Wewill show that all the discussed spectral properties of the PAM crystals can be quantitatively described in terms of a model by assuming that a centrosymmetric dimer of the N_H 3 3 3 O hydrogen bonds is the bearer of the basic crystal spectral properties. This means that from a unit cell of a crystal the model selects only those translationally independent pairs of hydrogen bonds that are most strongly exciton coupled. The exciton coupling involves the pairs of the N_H 3 3 3 O hydrogen bonds that are connected with the symmetry center inversion operation.

Moreover, each hydrogen bond belongs to another, translationally nonequivalent chain of the associated molecules. Indeed, such dimeric systems of the hydrogen bonds are considered responsible for the isotopically diluted crystal spectra. The relatively weak exciton coupling in the unit cell, involving these two translationally nonequivalent dimers are only responsible for GPCR Signaling the negligibly small splitting of the spectral lines. This effect differentiates the spectra measured for the two different crystallographic faces. These latest fine spectral effects seem to be attributed to the couplings seem to concern the adjacent hydrogen bonds in each chain.

Then we will prove that the contour shapes of the residual N_H and N_D bands can be quantitatively reproduced by the model calculations based on the formalism of the strong coupling theory of the IR spectra of a centrosymmetric dimeric hydrogen 6_8 bond system. 4. 2. Model Calculations of the N_H and N_D Band Contour Shapes. Model calculations, aiming at reconstituting the residual and band DNA Damage shapes, were performed within the limitsofthestrong coupling theory, foramodelcentrosymmetric N_H N_D 6_8 N_H 3 3 3 main O hydrogen bond dimeric system. We assumed that the N_H and N_D band shaping mechanism involved a strong anharmonic coupling, including the high frequency proton stretching vibrations and the low frequency N 3 3 3 O hydrogen bridge stretching vibrational motions. According to the consequences of the strong coupling model for centrosymmetric.

The N_H band from the PAM band shape simulation PARP in the limits of the strong coupling model: the plus dimeric band reconstitut ing the symmetry allowed transition band, the minus dimeric band reproducing the forbidden transition band, the superposition of the plus and minus bands with their statistical weight parameters N_D band from the band shape simulation in the limits of the strong coupling model: the plus dimeric band reconstituting the symmetry allowed transition band, the minus dimeric band reproducing the forbidden transition band, the superposition of the plus and minus bands with their statistical weight parameters Ft and F_ taken into account. The corresponding experimental spectrum treated as a superposition of two component bands. They corre sponded to the excitation of the two kinds of proton stretching vibrations, each exhibiting a different symmetry. For the C i point symmetry group of the model dimer, the proton totally symmetric in phase vibration normal coordinate belongs to the A g representation when the nontotally symmetric out of phase vibration coordinate belongs to the A u represen tation.