A new triphenylpyridine-containing aromatic diamine monomer named 4-phenyl-2,6-bis(4-aminophenyl) pyridine was successfully synthesized. A series of polyimides (PIs) with triphenylpyridine moieties were prepared from the newly synthesized diamine monomer via a one-step polymerization with oxydiphthalicanhydride. All the PIs were amorphous and showed excellent solubility in many polar aprotic solvents at room temperature and most of them could afford flexible, transparent, and tough films with good mechanical properties. All the PIs had useful levels of thermal stability associated with high glass-transition temperatures (299-341 A degrees C), 10 % weight-loss temperatures in excess of 537 A degrees C, and char yields at 800 A degrees C in nitrogen higher than 54.9 %.