Manipulating Metal Complex Assembly (and Function) via Structure-Directing "Third-Generation" Scorpionate Ligands

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Daniel Reger at the University of South Carolina to synthesize new types of coordination compounds with highly organized molecular and supramolecular structures based on poly(pyrazolyl)borate, multitopic poly(pyrazolyl)methane and related ligands. These ligands, which are designed to bond one or more metal ions in a predetermined architectural arrangement are used to prepare complex molecular and supramolecular structures that show distinct electrical, photophysical, and magnetic properties. Ligands designed to bring two coordinatively unsaturated metals into proximity, so as to result in bimetallic activation, will be used to prepare a series of homobimetallic complexes containing an unusual structural arrangement of a linear M-X-M ion bridge (M = first row metal; X = F-, H-, Cl-, O2-, N3-). The ligands are flexible enough to allow variable MM distances so as to yield a variety of distinct magnetic, Mossbauer (M = Fe) and electrochemical properties. Heterobimetallic complexes that contain two different luminophores will be prepared and studied with newly prepared un-symmetrical ligands. These new complexes containing different types of multi-chromophoric metal centers should exhibit photophysical properties that will be influenced by the anticipated highly organized supramolecular structures. In an unusual variation of multi-chromophoric molecules, metal complexes containing ligands with the photoactive 1,8-naphthalimide synthon will be prepared. This group has a strong directionally controlled pi-stacking interaction that dominates its supramolecular structures leading to the ability to prepare unusual metalorganic frameworks, including higher-order pillared networks. Newly developed tris(pyrazolyl)borate ligands will be used to make fundamental advancements in the field of spin-crossover Fe(II)N6 complexes, complexes with switchable domains with possibilities for development as memory devices. New complexes will be prepared and studied that have attached functional groups capable of organizing the Fe(II)N6 complexes into highly-ordered arrays, strongly impacting on the spin-crossover behavior. Poly(pyrazolyl)methane ligands will be developed that can act as the axle in rotaxanes, which can be functionalized with metal systems to prepare mechanically interlocked compounds containing photoactive metal units. Through a collaboration with Professor Ken Brown at Winston-Salem State University undergraduate students from underrepresented groups in science students will work with the South Carolina group. The also has an agreement with Columbia College, a local womens college, for the use of NMR and mass spectroscopy facilities at the University of South Carolina.