Molecular tectonics

Abstract

Tectons are defined as molecules whose interactions are dominated by specific attractive forces that induce the assembly of aggregates with controlled geometries; molecular tectonics is the art and science of supramolecular construction using tectonic subunits. Intermolecular hydrogen bonds offer a particularly effective force for promoting controlled tectonic aggregation, and tectons able to participate in extensive networks of hydrogen bonds can be constructed by the simple expedient of attaching multiple 2-pyridone subunits to carefully chosen molecular frameworks. For example, tectons that incorporate four tetrahedrally oriented 2-pyridone subunits are predisposed to generate diamondoid networks or related three-dimensional lattices. As expected, crystallization of nominally tetrahedral tectons 8, 10, and 11 produces diamondoid hydrogen-bonded networks with distances between the centers of adjoining tectons varying from approximately 12 to 20 Å. These networks define large internal volumes that are filled by a combination of independent interpenetrating diamond networks and enclathrated guests. Such networks are porous enough to permit the exchange of guests and robust enough to remain intact, even though their structural integrity is maintained only by hydrogen bonding. Three-dimensional hydrogen-bonded networks not based on diamond can be generated by the association of related tectons, including stannane 13, that incorporate features designed to make them more deformable. These observations are important because they suggest that clever application of the strategy of molecular tectonics can be used to build an unlimited range of ordered three-dimensional organic networks with some of the desirable properties of zeolites and related inorganic materials, including high structural integrity, potentially large void volumes, and adjustable microporosity.