Office: PHSC 436 Phone: (405) 325-4836 Email: RHalterman@ou.edu Full Publications List

Ronald L. Halterman Professor B.S. (University of California, Riverside, summa cum laude, Phi Beta Kappa) 1980 Ph.D. (University of California, Berkeley) 1985 College of Natural and Agricultural Sciences Outstanding Graduating Senior Award, 1980 Alumni Award for Most Outstanding Graduating Senior, 1980 NIH Postdoctoral Fellow (Massachusetts Institute of Technology) 1985-1987 Alexander von Humboldt Fellowship - TU Berlin, May 1995-July, 1996. Regents' Award for Superior Accomplishment in Research, 1997 DAAD (German Academic Exchange Service) Visiting Professor, Technical University of Berlin, April 2001 - August, 2002

Division: Organic Chemistry Research Interests Synthesis of functional molecules-A:  Substituted metallocenes and chiral porphyrins for stereoselective catalysis. Synthesis of functional molecules-B:  preparation of chiroptical molecular switches. Synthesis of functional molecules-C:  preparation of substituted catenanes for control of molecular motion and materials applications.

Research Description

Conformational Mobility in Potential Molecular Ratchets

Unlike macroscopic mechanical devices, molecular-scale rotors have been demonstrated to achieve preferential unidirectional motion through controlled and directed input of energy such as chemical or photochemical energy.  Our research is aimed at understanding the factors that favor the motion of a molecular ring faster in one direction than in the reverse direction.  We are focusing our efforts on the exchange between two isoenergetic coordinating sites of a ring along a second catenated ring.  In initial studies we have established the ability to turn "on" or "off" pathways over the "top" or "bottom" of  bipyridinium-based catenanes as illustrated in 1 below.  We are currently extending the project to incorporate biased pathways as in 2 to examine their effect on the rates of conformational interconversions.

Previous Projects

Our current work on molecular motion has grown out of our previous research work in the area of stereoselective reactivity.  In those studies, we prepared novel chiral highly symmetrical metalloporphyrins, prepared sterically unbiased substrates to examine the effectiveness of stereoelectronic control of diastereoselective reactions and our major research effort in the preparation and application of chiral metallocenes.  Some examples are shown here, for additional examples see our group home page.  A key underlying issue in all of these projects has been the centrality of synthesis in the service of increasing our understanding of molecular processes.

Halterman, Ronald L.; Martyn, David E.; Pan, Xingang; Ha, Diana B.; Frow, Michael; Haessig, Kathryn. Path Selection for Conformational Interconversions in [2]Catenanes. Organic Letters (2006), 8(10), 2119-2121.

Halterman, Ronald L.; Martyn, David E. Translational Isomerizations in [2]Catenanes with Unsymmetrically Substituted Resorcinol-Based Tethers. Journal of Organic Chemistry (2007), 72(21), 7841-7848.

Martyn, Tami A.; Moore, Jason L.; Halterman, Ronald L.; Yip, Wai Tak. Cucurbit[7]uril Induces Superior Probe Performance for Single-Molecule Detection. Journal of the American Chemical Society (2007), 129(34), 10338-10339.

Halterman, Ronald L.; Pan, Xingang; Martyn, David E.; Moore, Jason L.; Long, Andrew T. Conformational Interconversions in [2]Catenanes Containing a Wide Rigid Bis(p-benzyl)methyl Spacer. Journal of Organic Chemistry (2007), 72(17), 6454-6458.

"Preparation of Chiral Annulated Indenes Derived from Nopinone, Verbenone and Menthone"  Halterman, R.L. and Crow, L.D. Tetrahedron Letters 2003, 44, 2907-2909

"Synthesis, Structure and Catalytic Activity of some new chiral (-)-2-Menthylindenyl- and (-)-2-Menthyl-4,7-dimethylindenyl Rhodium Complexes." Schumann, H.;  Stenzel, O.; Dechert, S.; Girgsdies, F.;  Blum, J.; Gelman, D.; R. L. Halterman,R.L.  Eur. J. Inorg. Chem., 2002 211-219

"Menthyl Functionalized Chiral Nonracemic Bis(indenyl) Complexes of Zirconium, Iron, Nickel, and Ruthenium" Schumann, H.; Stenzel, O.; Dechert, S.; Halterman, R. L. Organometallics  2001,  20,  1983-1991

Synthesis, Characterization and Polymerization Properties of Bis(2-menthylindenyl)zirconium Dichloride and Bis(2-menthyl-4,7-dimethylindenyl)zirconium Dichloride Halterman, R. L.; Fahey, D.R.; Bailly, E.F.; Dockter, D. W.; Stenzel, O.;  Shipman, J. L.; Khan, M. A.; Dechert, S.; Schumann, H. Organometallics  2000, 19, 3824-3829.

"The Synthesis of C7-C7'-Ethylene and -Methylene Bridged C₂-Symmetric Bis(Indenyl)zirconocene and -titanocene Dichlorides" Halterman, R. L.; Combs, D.; Khan, M. A. Organometallics  1998, 17, 3900-3907.

"Synthesis of Chiral Titanocene and Zirconocene Dichlorides" Halterman, R. L., in Metallocenes, Halterman, R. L.; Togni, A., eds; Wiley-VCH, New York, 1998, 455-544.

"Synthesis and Catalytic Reactivity of D4-Symmetric Dinorbornabenzene-Derived Metallotetraarylporpyrins" Halterman, R. L.; Jan, S.-T.; Nimmons, H. L.; Standlee, D. J.; Khan, M. A. Tetrahedron 1997, 53, 11257-11276.

"Synthesis and Application of Chiral Cyclopentadienylmetal Complexes"  Halterman, R. L. Chem. Rev.  1992, 92, 965-994.

"Catalytic Asymmetric Epoxidation of Unfunctionalized Alkenes Using the First D₄-Symmetric Metalloporphyrin"  Halterman, R. L.; Jan, S.-T. J. Org. Chem. 1991, 56, 5253-5254.