Solvation controlling reaction paths and gel-formation in imide derivatives

1,8-Naphthalic anhydride condenses with 4-nitro-1,2-diaminobenzene in acetic acid to give 11-nitrobenzo[d,e]benzo[2,1-a]isoquinoline-1,3-dione (1), whereas the same reaction carried out in DMF gives 2-(2-amino-4-nitrophenyl)-benzo[d,e]isoquinoline-1,3-dione (2). The condensation reaction of 1,8-naphthalic anhydride with 1-amino 3,5-benzene dicarboxylic acid leads to corresponding imide, which forms a gel in a mixed solvent such as water in DMSO. A similar compound 5-(1,3-dioxo-1,3-dihydroisoindol-2-yl)-isophthalic acid derived from phthalic anhydride forms gel in a mixed solvent of DMSO and water, whereas a crystalline solvate of DMSO with 2 could be obtained upon crystallization from DMSO. The crystal structure of this solvate is determined and its structure is compared with 2-(1,3-dioxo-1,3-dihydro-isoindol-2-yl)-benzoic acid. The latter does not form a gel in the mixed solvent and adopts an intermolecular hydrogen bonded structure.