Contribution à l'etude des spectres de vibration du thiazole

Etude des spectres de vibration de l'isothiazole et des spectres infrarouges de trois mono et dideutério isothiazoles

“…tableaux 3 et 4). Soulignons, en faveur de I'attribution de la frtquence 1236 cm-' une vibration de dtformation 6(CH), dans le spectre de l'isothiazole, que l'oscillation 6(CH) la plus tlevte de nombreux dtrivts heterocycliques pentagonaux, est observte vers 1250 f 20 cm-' (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). Par analogie, nous relions aussi un mouvement 6(CH), la suite vers 1200 cm-', composte de bandes i.r.…”

“…1) et devient fine, symCtrique et beaucoup plus intense, dans celui du dideutkrio-4,5 isothiazole a 1'Ctat dissous dans un solvant neutre. C'est ce comportement, analogue a celui de certaines absorptions y(CH) dans les hCtCrocycles thiazoliques (19)(20), qui nous a incitCs a choisir, pour la vibration y(CD), cette frCquence plut6t que celle, plus basse, a 541 cm-', qui a Ct C rattachke a l'oscillation de noyau I ? , .…”

Mechanical Properties versus Morphology of Ordered Polymers. Volume III. Part I

“…In this case, the Raman spectra were obtained using less Since the isotropic to nematic phase transformation occurs near 5% concentration, the spectral changes cannot be associated with the change in the intermolecular interaction, but rather with the structure of the polymer. On the basis of the vibrational spectra obtained for biphenyl and heterocyclic model compounds [26][27][28][29][30], the Raman bands observed were assignable to the stretching vibrations of the heterocyclic group, the phenyl ring and the C-C bond linking them [12].…”

“…The angle predicted from conformational energy calculations is 600 [20], larger than actually measured. It appears that intermolecular interactions tend to keep the angle low in the solid state [28,29]. When the material is stressed, or in material lacking orientational order, it is reasonable to assign the changing polarization to a disruption of the intermolecular forces or to a direct weakening of the bond connecting two rings, thus affecting the coplanarity of the two rings.…”

“…Tentative assignments based on model compounds and the measured transition moments are listed in Table 1 [12,13,[14][15][16][17][18].…”