| Popis: |
(Carbazole + tert -amide) systems were investigated through measurement of (solid + liquid) equilibria (s.l.e.), i.r. study, and semi-empirical calculations. The s.l.e. studies included three systems, namely (carbazole + tetramethylurea, orN , N - diphenylacetamide, or N -acetylcarbazole). In spite of the identical tertiary N-atom, andC = O group occurring in each studied amide assumed to dominate molecular interactions, the liquidus curves have revealed the presence of a hydrogen-bond complex only in the first system. The remaining two are simple eutectic systems, probably owing to sterical hindrance exhibited by large substituents. Each system, as well as (carbazole + N, N - dimethylformamide) were studied using i.r. spectroscopy in 1,1,2,2-tetrachloroethene solutions. In contrast to s.l.e. data, hydrogen-bond formation manifested itself in each system studied by the i.r. method. The enthalpy of complex formation was determined from the spectroscopic data for each system except for (carbazole + N -acetylcarbazole). The i.r. studies were supported by semi-empirical calculations performed for the optimized hydrogen-bond geometries. |
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