Synthesis and characterization of heterocyclic, and optically active poly(amide-imide)s by phosphorylation polycondensation

N, N'-Pyromelliticdiimido- di-L-methionine ( 1), N, N'-Pyromelliticdiimido- di-L-alanine ( 2), N, N'-Pyromelliticdiimido- di-L-phenylalanine ( 3), and N, N'-Pyromelliticdiimido-di-L- leucine ( 4) were prepared from the reaction of Pyromellitic dianhydride with corresponding L-amino acids in a mixture of glacial acetic acid and pyridine solution ( 3/2 ratio) under refluxing conditions. The phosphorylation polycondensation of the corresponding diimide-diacid monomers with 4-phenyl-2,6-bis(4-aminophenyl) pyridine ( 6) or 4-(p-methylthiophenyl)-2,6-bis( 4- aminophenyl) pyridine ( 8) were carried out in N-methyl-2-pyrolidone ( NMP). The resulting poly (amide-imide)s were obtained in quantitative yields, showed admirable inherent viscosities (0.20- 0.97 dl g(-1)), were soluble in polar aprotic solvents, showed good thermal stability and high optical purity. The synthetic compounds were characterized by IR, MS, H-1 NMR and C-13 NMR spectroscopy, elemental analysis and specific rotation.