Nitroaniline crystal structures, hydrogen bonds

The other important role that hydrogen bonds play in nitroaniline crystal structures... 

Three general dimer types were considered for both nitroanilines A, the optimal dimer with two distinct H-bonds, each between one amino-hydrogen and one nitro-oxygen B, a relaxed geometry, with at least one bifurcated H-bond that is the local minimum closest to the crystal structure, and, C, the structure obtained by fixing the H-bonds at their experimental (crystal structure) distances and optimizing the rest of the dimer within the same constraints as A and B. Structure C is closest to the experimental structure. 

Hexakis(2,6-di-0-methyl)-a-CyD complexes with a small guest molecule, such as iodine and 1-propanol, crystallize with the cage-type packing structure [185]. Compared with the structure of the corresponding -CyD complex, the guest molecules in the both complexes are shifted to the secondary hydroxyl side from the center of the cavity. 3-Iodopropionic acid [186], m-nitroaniline [187], and acetonitrile [188] are also fully accommodated in the host cage . A 3-0 acetylated host, hexakis(2,6-di-0-methyl-3-0-acetyl)-a-CyD, was crystallized from butylacetate [189]. In spite of the disruption of intramolecular hydrogen bonds, the host molecule is in a round shape because of the inclusion of butylacetate. 

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