ELECTRONIC AND MOLECULAR-STRUCTURES OF 1,3,5-TRIS(PHENYLMETHYLENE)BENZENE (S=3) AS MODELS FOR DISCOTIC HIGH-SPIN LIQUID-CRYSTALS - SINGLE-CRYSTAL ESR AND X-RAY-DIFFRACTION STUDIES

The electronic and molecular structures of the two-dimensional septet- state molecules(S=3), 1,3,5-tris(p-methoxyphenylmethylene)benzene A an d 1,3,5-tris(phenylmethylene)benzene B, were investigated by single-cr ystal ESR spectroscopy. A was designed for a prototypical core model f or discotic liquid-crystalline organic high-spin molecules. We determi ned the fine-structure constants of A by the ESR spectroscopy and anal yzed the crystal and molecular structures of B by X-ray diffraction. T he effect of the methoxy functional group on the fine-structure consta nts was found: the effect showed up in the significant reduction of th e fine-structure constant D value for A, indicating the modification o f the topologically controlled robust pi spin polarization. The observ ed non-vanishing E value is in accord with the molecular symmetry and crystal structure of the host molecule, 1,3,5-tris(alpha-benzoyl)benze ne.