FUSED STATE C-13-NMR STUDY ON MOLECULAR-ORIENTATION IN A CARBONACEOUS MESOPHASE

Molecular behavior of coronene, pyrene, and hexamethylbenzene blended in a carbonaceous mesophase was investigated by fused state C-13-NMR. Sharp signals attributed to aromatic carbons of these compounds in the fused mesophase pitch were observed at markedly lower fields compared with those in solution, indicating that their aromatic planes were oriented parallel to the mesophase lamellae aligning along the magnetic field. Order parameters of these compounds, as well as the mesophase constituents, were calculated from the observed chemical shifts, a correlation between their order parameter and molecular weight being observed. This correlation suggested that probe molecules in the fused mesophase behave like mesogens.