Crystal engineering using f-metals: Structural systematics of uranium and neodymium containing materials

Crystal engineering is an effective route to the production of metal-organic coordination polymers as it allows for a logical approach to the design of the materials. We have applied this approach to the construction of a family of novel metal-organic coordination polymers containing f-metals. The use of f-metals is attractive because their inherit coordination environments that allow for a variety of primary building units. Ln(III) metals have a spherical coordination environment and are typically found coordinated to nine or ten donor atoms. Ac(VI), specifically U(VI), is found as a linear triatomic cation (UO22+) in aqueous solution which only allows for further bonding to occur in the equatorial plane giving rise to three possible primary building units: square, pentagonal and hexagonal bipyramids. These primary building units can polymerize into larger secondary building units (SBUs) such as dimers, tetramers and chains which is a recurring theme in our materials. We have successfully been able to crystallize a series of novel structures using either Nd(III) or U(VI) bound to aliphatic dicarboxylic acids of various lengths. In addition we have been able to influence the topologies of the U(VI)-dicarboxylates by the addition of a second bipyridine organic species. Presented herein is the structural systematics of a family of novel metal-organic coordination polymers containing f-metals.