Synthesis and crystal structures of three Schiff bases derived from 3-formylacetylacetone and o-, m- and p-aminobenzoic acid

Abstract

Treatment of 3-formylacetylacetone with the isomeric o-, m- and p-aminobenzoic acids led to the formation of the corresponding Schiff bases, namely, 3-[(2-carboxyphenylamino)methylidene]pentane-2,4-dione, 1, 3-[(3-carboxyphenylamino)methylidene]pentane-2,4-dione, 2, and 3-[(4-carboxyphenylamino)methylidene]pentane-2,4-dione, 3, all C13H13NO4, that contain a planar amino-methylene-pentane-2,4-dione core with a strong intramolecular N—H...O hydrogen bridge. The carboxyphenyl groups attached to the nitrogen atom are almost coplanar to the central molecular fragment. Depending on the position of the carboxyl unit, different supramolecular structures with hydrogen-bonding networks are formed in the three title structures.