GLASS-FORMATION AND PHASE-TRANSITION OF NOVEL PI-ELECTRON STARBURST MOLECULES, 1,3,5-TRIS(PHENYL-2-THIENYLAMINO)BENZENE AND 1,3,5-TRIS(PHENYL-3-THIENYLAMINO)BENZENE

Novel pi-electron starburst molecules, 1,3,5-tris(phenyl-2-thienylamino)benzene (alpha-TPTAB) and 1,3,5-tris(phenyl-3-thienylamino)benzene (beta-TPTAB), are found to form amorphous glasses with well-defined glass-transition temperatures of 38 and 46 degrees C, respectively, while 1,3,5-tris(diphenylamino)benzene instantly crystallizes. The result leads to a concept of ''increasing the number of conformers of nonplanar molecules'' for a molecular design of amorphous molecular glasses. The glasses of alpha-TPTAB and beta-TPTAB are found to be transformed finally into crystals with the highest melting points via metastable crystals on heating.