4,6-Dinitro-N,N′-di-n-octylbenzene-1,3-diamine, 4,6-dinitro-N, N′-di-n-undecyl-benzene-1,3-diamine and N,N′-bis-(2,4-dinitro-phen- yl)octane-1,8-diamine

4,6-Dinitro-N,N′-di-n-octylbenzene-1,3-diamine, C22H ₃8N4O₄, (I), 4,6-dinitro-N,N′-di-n-undecyl-benzene- 1,3-diamine, C28H₅0N4O₄, (II), and N,N′-bis-(2,4- dinitro-phenyl)octane-1,8-diamine, C20H₂4N6O8, (III), are the first synthetic meta-dinitro-arenes functionalized with long-chain aliphatic amine groups to be structurally characterized. The intra- and inter-molecular inter-actions in these model compounds provide information that can be used to help understand the physical properties of corresponding polymers with similar functionalities. Compounds (I) and (II) possess near-mirror symmetry, with the octyl and undecyl chains adopting fully extended anti conformations in the same direction with respect to the ring. Compound (III) rests on a center of inversion that occupies the mid-point of the central C - C bond of the octyl chain. The middle six C atoms of the chain form an anti arrangement, while the remaining two C atoms take hard turns almost perpendicular to the rest of the chain. All three mol-ecules display intra-molecular N - H⋯O hydrogen bonds between the amine and nitro groups, with the same NH group forming a bifurcated inter-molecular hydrogen bond to the nitro O atom of an adjacent mol-ecule. In each case, these inter-actions link the mol-ecules into one-dimensional mol-ecular chains. In (I) and (II), these chains pack so that the pendant alkyl groups are inter-leaved parallel to one another, maximizing non-bonded C - H contacts. In (III), the alkyl groups are more isolated within the mol-ecular chains and the primary non-bonded contacts between the chains appear to involve the nitro groups not involved in the hydrogen bonding.