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B.S., University of Texas, Austin, 1996. Ph.D., University of California, Berkeley, 2000 (Kenneth N. Raymond). Postdoctoral: The Scripps Research Institute, 2001-03 (Julius Rebek, Jr.). Honors and Awards: Phi Beta Kappa; NIH Postdoctoral Fellow, 2002-03; NSF CAREER Award, 2006; Research Corporation Cottrell Scholar Award, 2006. At Oregon since 2003.
Research Interests:
Research in the group explores problems in coordination chemistry and organic synthesis using the relatively new field of supramolecular chemistry as a tool. Research projects include developing specific metal chelators for a variety of toxic and environmentally hazardous metals; using organic reactions to mediate inorganic cluster formation; designing efficient syntheses of nanoscale organic cage structures through supramolecular intermediates; and using multiple weak interactions within small molecule receptors to target environmentally and biologically relevant substrates. The research in the group spans a diverse range of disciplines: organic synthesis of ligands and receptors; inorganic chemistry of supramolecular coordination complexes and inorganic clusters; computer modeling and ligand design; analytical chemistry of metal extractants; solution thermodynamics of host-guest and metal-ligand complexes; and materials science of supramolecular assemblies. The characterization of these nanoscale molecules requires investigation by X-ray crystallography, calorimetry, multidimensional NMR techniques and other spectroscopic methods.
I. Supramolecular Main Group Chemistry and
Specific Metal Chelation
We are elaborating a design strategy for forming coordination capsules comprised
of toxic metal ions or main group elements (such as arsenic or lead). We
have recently shown that ligand H2L binds arsenic(III) within a very stable
As2L3 cage. Surprisingly, two As2L2Cl2 macrocycles were also isolated as
intermediates in the reaction. Applications in metal remediation, both environmental
and medical, are envisioned by designing the ligands to target a specific
toxic or hazardous metal ion. Furthermore, incorporating these nanoscale
coordination capsules into extended solid-state structures leads to applications
in materials science, and the novel cavity environments in these capsules
will lead to unusual host-guest properties.
II. Inorganic Nanoclusters
Developing predictive design strategies to prepare inorganic cluster compounds
has attracted much research interest, due in part to the potential applications
of these novel materials. We have developed an unusual new synthetic strategy
for preparing discrete inorganic clusters, and we have used this strategy
to prepare the first crystalline example of an inorganic tridecameric Ga
cluster (Ga13, see figure). This same facile synthetic methodology also
yields the analogous tridecameric aluminum complex and a mixed Ga/In tridecameric
cluster in preparative scales after several days. We are currently exploring
the use of these inorganic aggregates as synthons for the generation of
a wider range of particles and assemblies via exchange of the peripheral
water ligands with appropriate organic ligands.
III. Organic Nanocages & Molecular Recognition.
Self-assembly reactions have yielded a variety of spectacular
discrete three-dimensional nanoscale architectures. Covalent capture of
these self-assembled capsules can trap the assemblies as organic cages.
We seek to investigate the host-guest chemistry of these structures and
to explore their use as specific metal chelators for toxic metal ions.
Nature exploits the tandem use of hydrogen bonding, metal coordination, aromatic and van der Waals interactions, and the hydrophobic effect to bind small substrates. We are interested in mimicking this behavior by developing synthetic receptors that use multiple weak attractive forces, such as coordination chemistry and hydrogen bonding, to target environmentally and biologically relevant substrates.
Selected Publications:
Berryman, O. B.; Hof, F.; Hynes, M. J.; Johnson, D.W. “Anion-π Interaction Augments Halide Binding in Solution” Chem. Commun. 2006, 506-508.
Healey, E. R.; Vickaryous, W. J.; Berryman, O. B.; Johnson, D. W. "Self-Assembled Supramolecular Main Group Coordination Complexes" In BOTTOM-UP NANOFABRICATION: Supramolecules, Self-Assemblies, and Organized Films; Ariga, K., Nalwa, H. S., Eds.; American Scientific Publishers: Stevenson Ranch, 2006, in press.
Vickaryous, W. J.; Healey, E. R.; Berryman, O. B.; Johnson, D. W. “Synthesis and Characterization of Two Isomeric, Self-Assembled Arsenic-Thiolate Macrocycles” Inorg. Chem. 2005, 44, 9247-9252.
Carter, T. G.; Healey, E. R.; Pitt, M. A.; Johnson, D. W. “Supramolecular Secondary Bonding Interactions Stabilize Two Arsenic Thiolate Complexes” Inorg. Chem. 2005, 44, 9634-9636.
Rather, E.; Gatlin, J. T.; Nixon, P. G.; Tsukamoto, T.; Kravtsov, V.; Johnson, D. W. “A Simple Organic Reaction Mediates the Crystallization of the Inorganic Nanocluster [Ga13(µ3-OH)6(µ2-OH)18(H2O)24](NO3)15” J. Am. Chem. Soc. 2005, 127, 3242-3243. (Highlighted in Editor’s Choice in Science, 2005, 307, 1377.)
Vickaryous, W. J.; Herges, R.; Johnson, D. W. “Arsenic-π Interactions Stabilize a Self-Assembled As2L3 Supramolecular Complex” Angew. Chem. Int. Ed. 2004, 43, 5831-5833.
To Contact Dr. Johnson:
Phone: 541-346-1695
dwj@uoregon.edu
WEBMASTER
lynde@uoregon.edu
