Synthesis and characterization of new optically active polyamides containing 2-(4-nitro-1,3-dioxoisoindolin-2-yl)succinic acid and aromatic diamines via direct polycondensation

Abstract

A new class of optically active polyamides (PAs) (6a-e) having 4-nitro-1,3-dioxoisoindolin-2-yl pendent groups were prepared by direct polycondensation reaction of 2-(4-nitro-1,3-dioxoisoindolin-2-yl) succinic acid (4) with various aromatic diamines in a medium consisting of triphenyl phosphite, calcium chloride, pyridine, and N-methyl-2-pyrrolidone. The resulting new polymers were obtained in high yields with inherent viscosities ranging between 0.32 and 0.48 dL/g, and were characterized by elemental analysis, FT-IR spectroscopy, specific rotation, solubility tests, and thermogravimetric analysis techniques (TGA and DTG). Bulky pendent groups of the polymer chains disturb interchain and intrachain interactions and make these PAs readily soluble in polar organic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), NMP (N-methyl-2-pyrrolidone), and sulfuric acid. 2-(4-nitro-1,3-dioxoisoindolin-2-yl) succinic acid (4) was prepared by reaction of 3-nitrophthalic anhydride (1) and L-aspartic acid (2) in acetic acid solution.