The preparation of designed two-dimensional hydrogen bonded networks: Applications in material science

The development of a general strategy for the preparation of low dimensional solids is a worthy supramolecular goal because of the potential anisotropic property of the material. Our goal structure is the β-network since the resulting layered solids are challenging synthetic targets with useful applications. The preparation of layered solids does not require complete control over the solid state. Rather the fundamental requirement is control over some important features of the solid, in this instance, a molecule capable of forming two independent and nonparallel interactions. The self-assembly of these molecules would lead to β-networks; the subsequent stacking of the β-networks to layered solids. Since the successful supramolecular synthesis of β-networks depends critically on the strength, directionality and reliability of the intermolecular interactions, hydrogen bonds were used to prepare our β-networks. We have developed this strategy for the preparation of two-molecule or binary β-networks.; We can control the symmetry and molecular spacing within the β-networks. Control of intermolecular spacing and molecular repeat distances is an important property in the crystal engineering, the design and preparation of new molecular solids, because of the potential useful applications. An attractive application is the topochemical control of chemical reactivity. Among the topochemically-controlled reactions, the polymerization of diacetylene has attracted considerable attention because the resulting all-trans, fully-conjugated polydiacetylene polymer may possess unique optical or electrical properties and would be therefore of interest to material science. We have successfully used the two-molecule approach in the layering of diacetylenes and were fortunate to have also structurally characterized the polydiacetylene polymer single crystal by x-ray crystallography. We have recently explored the potential application of the topochemically-controlled polymerization of diacetylenes in the stabilization of open-channel networks.