MOLECULAR RECOGNITION IN THE SOLID-STATE - HYDROGEN-BONDING CONTROL OF MOLECULAR AGGREGATION

The design of molecular subunits that self-assemble into well-defined structures in the solid state is an area of intense current interest. A key to controlling the packing arrangement lies in manipulating the type and orientation of the non-covalent interactions between the subu nits. The strong and directional nature of hydrogen bonds has led to t heir widespread use in self-assembling systems. In the solid state, ru les have been delineated to allow the reasonable prediction of hydroge n-bonding packing patterns in crystals. This had led to a search for m olecular components that because of their hydrogen-bonding characteris tics will form persistent packing motifs in well-defined shapes or pat terns. We have recently discovered that a strong bidentate hydrogen bo nding interaction is formed between 2-amino-6-methylpyridine and carbo xylic acids. Bis(2-amino-6-methylpyridine) derivatives and dicarboxyli c acids will self-assemble into alternating cocrystal structures. The packing of the two components can be controlled in a rational way by c hanging the nature, size, and orientation of the spacer groups that li nk the hydrogen-bonding subunits.