Synthesis of tetrahedral molecular building blocks for the design of porous crystalline solids

We are investigating supramolecular building blocks to construct solids with nanoporous properties. We have shown previously that mono- and bis-2,6-dicarboxypyridines bind transition or lanthanide metals through metal ligand coordination and hydrogen bonds and hydrogen bonding into two-dimensional and three-dimensional scaffolds. Current efforts in our laboratory are focused on the synthesis of large tetrahedral building blocks that will exhibit nanoporous properties through metal-ligand coordinated aggregation. Organic building blocks are synthesized incorporating 2,6-dicarboxypyridine units covalently linked to acetylene units in symmetrical arrangements around the tetrahedral core. We currently use several synthetic approaches to form tetrahedral building blocks, in which Sonogashira coupling of aryls to acetylene is utilized. All compounds are characterized by ?H and ??C NMR and IR spectroscopies. Our goal is to build large tetrahedral building blocks that through metal-ligand coordination bonds will form expanded diamondoid frameworks. We expect the resulting structures will have large porous features (~ several thousand A?)