The preparation of a new unsymmetrical kink non-coplanar heterocyclic diamine, 1,2-dihydro-2-(4-aminophenyl)-4-[4-(3-phenyl-4-aminophenoxy)phenyl]- (2H)phthalazin-l-one (3), from a readily available unsymmetrical phthalazinone bisphenol-like (1) was described. The diamine can be directly polymerized with various aromatic bis(trimellitimide)s (4a-e) by using triphenyl phosphite and pyridine as condensing agents to give a series of new aromatic poly(amide imides) (5a-e) containing the kink non-coplanar phthalazinone heterocyclic units with inherent viscosities of 0.57-1.06 dL/g. The polymers were readily soluble in a variety of solvents such as N,N-dimethylform- amide, N,N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidinone, and even in pyridine and m-cresol and could be cast to form flexible and tough films. The glass transition temperatures were in the range of 315-340degreesC, and the temperatures for 5% weight loss in nitrogen were in the range of 487-512degreesC. (C) 2004 Wiley Periodicals, Inc.