198 Topics in Current Chemistry Editorial Board: A. de Meijere KN ...

102 R.E. Meléndez · A.D. Hamilton
Fig. 3. Tape structure formed by p-nitroaniline (1)
component and the dashed lines represent intermolecular interactions. In terms
of crystal engineering, the ribbon motif is less appealing since at this stage it is
the more complex to understand and control.
Tapes and ribbons have been of interest in crystal engineering due to various
applications in material sciences. Stabilization of the translation of molecules
through intermolecular forces in a solid can generate polarity, which is a necessary
condition for a number of physical properties. For example, small-molecule
nitroaniline compounds show preference for a motif that involves one amino
proton associating with both oxygens of a nitro group, leading to the formation
of a tape structure (Fig. 3). In particular, p-nitroaniline (1) has been studied for
its non-linear optical properties [21].
The sheet archetype has received much interest because of its potential to
generate structural patterns that contain voids, which may in turn have applications
in the area of zeolitic materials. Trimesic acid (2) (Fig. 9) has been extensively
studied for this purpose [22]. However, Etter and Frankenbach have been
able to form polar sheets when 2,5-dinitrobenzoic acid (3) and 4-aminobenzoic
acid (4) are cocrystallized by using the nitro-amine and carboxylic acid recognition
motif (Fig. 4) [23].
We will present examples of tapes, ribbons, and sheets based on hydrogen
bonding and other intermolecular interaction patterns. The use of both strong
hydrogen bonding groups such as carboxylic acids and amides, as well as, weak
interactions such as C-H◊◊◊O hydrogen bonds and iodo◊◊◊nitro polarization
interactions will be covered.
3
Hydrogen Bonding
Hydrogen bonding is without doubt the most studied intermolecular interaction,
presumably due to its frequent presence in organic solids and biological
molecules. Various attempts have been made to define the hydrogen bond [24,
25] and many detailed investigations of its properties have been carried out [9,
26]. Pioneering scientists such as Etter [27, 28], Leiserowitz and Schmidt [16, 17],
Jeffrey and Saenger [29, 30], and Taylor and Kennard [31] have conducted extensive
studies of the solid-state structures of organic compounds in a search for
patterns, directionality, and strength in the occurrence of hydrogen bonding.
The selectivity and directional nature of hydrogen bonding has led to its
extensive use in the construction and stabilization of large non-covalently bonded
molecular and supramolecular structures. Hydrogen bonds are formed when