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Toward poly(aminophthalimide), structures of dimers and trimers

“…N-Arylmaleimides 13b,c were prepared by a two-step imidation of maleic anhydride with 7b,c according to the literature. 37 2,5-Diiodothiophene-1,1-dioxide (15) was selected as a diene substrate because elimination of sulfur dioxide from the Diels-Alder adduct and the subsequent aerobic oxidation to aromatize the product were highly expected to take place spontaneously after the [4+2] cycloaddition. 38 Indeed, heating a mixture of 15 and 13b or 13c in DMF at 130 C for 18-22 h gave the corresponding 3,6-diiodophthalimides 17b,c, albeit in rather low yields.…”

“…The hydrogen bond distances of PAP dimers 3a,b are 0.15-0.35 Å longer than that of PUP dimer 20a. The two phthalimide units (A and B) in 3a,b are mutually tilted by [35][36][37][38][39][40][41] to avoid a steric (and possibly electrostatic) repulsion between the aromatic ortho protons. It seems that the tilt angle is influenced by substitution on the phenyl rings, when one compares 3a and 3b.…”