Salts of 3,5-dinitrobenzoic acid with organic diamines: hydrogen-bonded supramolecular structures in one, two and three dimensions.

The trigonally trisubstituted carboxylic acid 3,5-dinitrobenzoic acid, (O(2)N)(2)C(6)H(3)COOH, forms 2:1 salts with a range of organic diamines L, with the general composition [LH(2)](2+) x [[(O(2)N)(2)C(6)H(3)COO](-)](2). When L is a bis-tertiary amine the hard N-H...O hydrogen bonds generate finite three-component aggregates, anion...cation...anion, and these aggregates are further linked by soft C-H...O hydrogen bonds to form one-dimensional molecular ladders when L is N,N,N',N"-tetramethyl-1,2-diaminoethane and chains of rings when L is 4,4'-dipyridylethane or 4,4'-dipyridylethene; two-dimensional sheets are formed when L is 1,4-diazabicyclo[2.2.2]octane and a three-dimensional framework is formed when L is N,N'-dimethylpiperazine. When L is the bis-secondary amine piperazine, the hard N-H...O and soft C-H...O hydrogen bonds each generate continuous motifs in the form of distinct chains of rings, the combination of which generates sheets, while when L is the bis-primary amine 1,2-diaminoethane the hard N-H...O hydrogen bonds alone generate a three-dimensional framework.