MOLECULAR-CRYSTALS WITH DIMENSIONALLY CONTROLLED HYDROGEN-BONDED NANOSTRUCTURES

Molecular crystals constructed by hydrogen bonding can be Viewed as ha ving nanostructural elements consisting of ordered, supramolecular hyd rogen-bonded networks. These networks, whose dimensionalities and moti fs are governed by the molecular structure and hydrogen-bonding topolo gy of their constituents, can serve as ''modules'' in the design and s ynthesis of molecular materials. Robust supramolecular modules can red uce significantly the number of possible solid-state packing motifs, a key goal of crystal engineering strategies which aim to design and sy nthesize molecular solids with controlled solid-state structure and pr operties. Several examples of hydrogen bonded modules in molecular cry stals are described, including one-dimensional hydrogen-bonded wires, two-dimensional hydrogen-bonded layers, and nanoporous hydrogen-bonded lattices with voids having differing dimensionalities. The presence o f reliable modules in these materials provides for a better general un derstanding of the organization principles governing molecular and sol id-state assembly by reducing the number of variables in systematic st udies.