Berea College Chemistry
Dr. Lee E. Roecker
Associate Professor of Chemistry
Berea College, CPO 1966
Berea, KY 40404
Phone: (859) 985-3318
[EDUCATION] [RESEARCH INTERESTS] [PUBLCATIONS/PRESENTATIONS][UNDERGRADUATE COLLABORATORS]
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Course Information for Students in Natural Science This link will lead you to the class syllabus, suggested readings, practice exercises, and study guides for my Natural Science class taught during the Spring 2001 term.
Course Information for Students in GST 256 A Chemist's View of Space Exploration
· B.S., University of Cincinnati, 1981; M.S., 1982-- Worked with Edward Deutsch as an undergraduate and M.S. student on the base hydrolysis of cobalt(III) complexes coordinated by thioether ligands.
· Ph.D., University of North Carolina, 1985--Worked with Thomas J. Meyer studying the oxidation mechanisms of Ru(IV) oxo complexes.
· Postdoctoral work at The Australian National University from 1985-1987 working with Alan M. Sargeson and at The Ohio State University from 1987-1988 working with Daryle H. Busch.
Transition Metal Surfactants
In 1993, Sargeson and Behm reported soap-like molecules that destroy the surface membranes of parasitic worms. One of these molecules has a water soluble head which carries a tripositive electrical charge due to a transition metal, cobalt(III). The molecule also has a long alkyl tail that is fat soluble. Molecules similar in structure to this include soaps, detergents, and the walls of cells. If we put some grease in water and add soap, the hydrophobic portion of the soap molecule will bury itself in the glob of grease. More and more soap molecules do the same thing and eventually the grease is broken down into smaller globs that are now essentially surrounded by the water soluble head groups. The grease will now dissolve in water and can be washed away.
Sargeson's molecule above is thought to dissolve the cell walls of intestinal worms in a like manner. When a dilute solution of this molecule is placed in solution with tapeworms, their membranous outer structures start to disintegrate within 8 minutes. SargesonŐs basic premise is that larger molecules with more highly charged heads might bind more tightly to cell membranes and thus have a more disruptive effect on cell membranes.
Not all surfactant tails are composed of simple alkyl linkages, however. The molecule pardaxin, for example, is a polypeptide composed of 33 amino acids. One end of the molecule, the hydrophilic end, is more water soluble than the other end. These solubility differences are due to the side chains present on the amino acids. Pardaxin is produced by some species of flatfish as a defense against predators. A possible mode of action has been proposed. The tail of the pardaxin molecule penetrates the cell walls of the predators gills (just like the soap tail enters grease) until it is stopped by the hydrophilic head group. The molecules then migrate towards each other forming a channel from which the cell contents leave. The resulting distress to the predator is enough of a distraction that the prey can escape. This process must occur very rapidly and with great efficiency.
My research students are currently linking transition metal containing head groups to pardaxin-like tails. These hybrid molecules will allow us to examine how charged head groups affect the ability of pardaxin-like polypeptides to disrupt cell membranes. Our initial work is concentrating on the preparation and characterization of several of transition metal complexes that are appended by amino acids and short polypeptides. Future work will produce hybrids with longer polypeptide chains attached and investigate how these new molecules interact with cell membranes.
References
1. Thompson, S.A.; Kazou,T.; Nakanishi, K.; Kubota, I. Science 1986, 233,
341-343.
2. Behm, C. A.; Creaser, I. I.; Korybut-Daszkiewicz, B.; Geue, R. J.; Sargeson,
A. M.; Walker, G. W. J. Chem. Soc. Chem Commun. 1993, 24, 1844.
Thiourea Complexes of Cobalt(III)
As a followup to our published work on urea ligands coordinated to cobalt(III) {"Synthesis, Characterization, and Reactivity of Urea Derivatives Coordinated to Cobalt(III)." Lee Roecker, Janet Akande*, L. Nelson Elam*, Irina Gauga*, Billy W. Helton*, Miranda C. Prewitt*, Alan M. Sargeson, Jason H. Swango, Anthony C. Willis, Tianpei Xin* and Jun Xu*. Inorg. Chem.1999, 38, 1269-1275} we are extending this work to thiourea ligands. Our interest was to see how the reactivity of the complexes might be altered or perhaps isolate reaction intermediates. What we thougth might be a simple extrapolation from the oxygen to the sulfur systems has turned out to be complicated. We are actively working on this project and hope to have the system figured out soon.
Monitoring Sustainable Soils
In 1999, the Berea College Department of Agriculture and Natural Resources revitalized a 5 acre community garden plot. In this renewal, most of the gardens were designated as "organic" and are now being tended with sustainable agricultural practices in mind. Several test areas were designated- no till, deep beds, etc, and several methods of composting are being examined. In the summer of 1999, we started to monitor soil nitrate throughout the growing season on these plots. We plan to continue working closely with the Department of Agriculture and Natural Resources to monitor pesticide residue, pesticide drift from neighboring "non-organic" plots, and make various measurements of soil and compost quality.
Professional Organizations
- American Chemical Society (1980-present)
- National Council of Undergraduate Research (1993-1998)
- Kentucky Academy of Sciences (1991-present)
- Kentucky Academy of Sciences Board of Directors (1996-2000)
Publications (* denotes undergraduate student)
- 18. "Synthesis, Characterization, and Reactivity of Thiourea Derivatives Coordinated to Cobalt(III)" Lee Roecker, Alison Anderson*, Elizabeth Pearl Smith*, Sanjeewa Goonasekera*, Cawas B. Engineer*, Joan Fetty*, Charles Kaiza*, Jeanette Krause-Bauer. Manuscript in preparation for submission to Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry in 2000.
- 17. "Synthesis and Base Hydrolysis of Cobalt(III) Complexes Coordinated by Monodentate and Bidentate Thioether Ligands. Chelate Effects and the SN1(CB) Mechanism." Lee Roecker, Michael Clark*, Thomas Demond*, L. Nelson Elam*, Billy Helton*, Regina Hicks*, Thane Morgan*, Pele Okullo*, Gregory Reeder*, Matthew J. Saderholm*, Manuel San*, J. Kiely Law*, Jason H. Swango*, Craig Thompson*, Jeanette Krause-Bauer. Manuscript in preparation for submission to the Australian Journal of Chemistry in 2000.
- 16. "Synthesis, Characterization, and Reactivity of Urea Derivatives Coordinated to Cobalt(III)." Lee Roecker, Janet Akande*, L. Nelson Elam*, Irina Gauga*, Billy W. Helton*, Miranda C. Prewitt*, Alan M. Sargeson, Jason H. Swango, Anthony C. Willis, Tianpei Xin* and Jun Xu*. Inorg. Chem.1999, 38, 1269-1275.
- 15. Roecker, L. "Space Exploration and Instrumental Analysis: An Internet Experience." Council on Undergraduate Research Quarterly.1997, March, 128-129.
- 14. Roecker, L.; Lee, S. M.*; Liu, L.*; Sun, L.*; Zaerpoor, K.* "Analysis Of First-Order Kinetic Data By A Differential Technique." Int. J. Chem. Kinet. 1997, 29, 333-338.
- 13. Ellis, A.*; Fultz, A.*; Hicks, R.*; Morgan, T.*; Parsons, L.*; Saderholm, M. J.*; Smith, L. A.*; Stabb, M.*; Starnes, J. K.*; Sun, L. J.*; Roecker, L. "Synthesis and Base Hydrolysis of the Pentaammine(dimethyl sulfide)cobalt(III) Ion." Aust. J. Chem. 1992,45, 2049-2055.
- 12. Binstead, R. A.; McQuire, M. E.; Dovletoglou, A.; Seok, W. K.; Roecker, L.; Meyer, T. J. "Oxidation of Hydroquinones by [(bpy)2(py)RuIV(O)]2+ and [(bpy)2(py)RuIII(OH)]2+. Proton-Coupled Electron Transfer." J. Am. Chem. Soc. 1992, 114, 173.
- 11. Alcock, N. W.; Creaser, I. I.; Curtis, N. J.; Roecker, L.; Sargeson, A. M.; Willis, A. C. "Intramolecular Hydrolysis of Coordinated Acetonitrile in a Binuclear Complex of Cobalt(III). X-Ray Crystallographic Analysis of Salts of [(tren)Co(µ-NH2,µ-L)Co(tren)]4+ (L = OH,CH3C(O)NH)." Aust. J. Chem. 1990, 43, 643-54.
- 10. Deutsch, E., Lydon, J.; Sargeson, A. M.; Willis, A. C.; Roecker, L.; "Intramolecular Quadridentate Synthesis: X-Ray Crystallographic Analysis of [(NH2CH2CH2NH2)Co-(NH2(CH2)2N=C(NH2)CH2S(CH2)2NH2)](CF3SO3)3.H2O." Aust. J. Chem. 1989, 42, 339-47.
- 9. Roecker, L.,Sargeson, A. M.; Willis, A. C. "Intramolecular Condensation of Coordinated Acetonitrile with an Amido Ion in a Binuclear Complex of Cobalt(III). X-ray Crystallographic Analysis of Na[(NH3)3Co(µ-OH,µ-NH2,µ-CH3C(NH)2)Co(NH3)3](S2O6)2.H2O." J. Chem. Soc. Chem. Commun. 1988, 119-121.
- 8. Gilbert, J., Roecker, L.; Meyer, T. J. "Hydrogen Atom Transfer in the Oxidation of Hydrogen Peroxide by [(bpy)2(py)RuIV=O]2+ and [(bpy)2 (py)RuIIIOH]2+." Inorg. Chem. 1987, 26, 1126-1132.
- 7. Roecker, L., Dobson, J. C.; Vining, W. J.; Meyer, T. J. "Oxygen Atom Transfer in the Oxidations of Dimethyl Sulfide and Dimethyl Sulfoxide by [(bpy)2(py)Ru(O)]2+." Inorg. Chem. 1987, 26, 779-781.
- 6. Roecker, L.; Meyer, T. J. "Hydride Transfer in the Oxidation of Alcohols by [(bpy)2(py)Ru(O)]2+. A kH/kD Kinetic Isotope Effect of 50." J. Am. Chem. Soc. 1987, 109, 746-754.
- 5. Roecker, L.; Meyer, T. J. "Hydride Transfer in the Oxidation of Formate Ion by[(bpy)2(py)Ru(O)]2+." Inorg. Chem. 1986, 108, 4066-4073.
- 4. Roecker, L.; Kutner, W.; Gilbert, J. A.; Simmons, M.; Murray, R. W.; Meyer, T. J. "Reactivity of [( bpy)2(py)Ru(O)]2+ and [(trpy)(bpy)Ru(O)]2+ in Basic Solution." Inorg. Chem. 1985, 24, 3784-3791.
- 3. Roecker, L.; Deutsch, E. "Base Hydrolysis of Bis(ethylenediamine)cobalt(III) Complexes Containing Chelated Thioether and Selenoether Ligand. Observation of Dramatic Medium Effects." Inorg. Chem. 1985, 24, 16-24.
- 2. Vanderheyden, J. L.; Ketring, A. R.; Libson, K.; Heeg, M. J.; Roecker, L.; Motz, P.; Elder, R. C.; Deutsch, E. "Synthesis and Characterization of Cationic Technetium Complexes of 1,2-Bis- (dimethylphosphino)ethane (DMPE). Structural Determinations of trans-[TcI(DMPE)3]+ Using X-ray Diffraction, EXAFS, and 99Tc NMR." Inorg. Chem. 1984, 23, 3184-4191.
- 1. Roecker, L.*; Dickman, M. H.; Nosco, D. L.; Doedens, R. J.; Deutsch, E. "Synthesis and Characterization of Bis(ethylenediamine)cobalt (III) Complexes Containing Chelated Thioether and Selenoether Ligands. Single-Crystal Structure Analysis of [(en)2Co(S(CHCON(CH2CH3COCH2)CH2CH2NH2)](ClO4)3." Inorg. Chem. 1983, 22, 2022-2028.
Selected Meetings/Workshops/Presentations
- Gordon Conference "Inorganic Reaction Mechanisms", Ventura California, March 1999.
- "Base Hydrolysis of Cobalt(III) Complexes Coordinated by Mono- and Bidentate Thioether Ligands. Chelate Effects and the SN1(CB) Mechansim." Departmental Seminar, Western Kentucky University, Fall, 1998.
- "Space Exploration and Instrumental Analysis: An Internet Experience." Physics Workshop Sponsored by the Appalachian College Association, Berea, November, 1997.
- Gordon Conference "Inorganic Reaction Mechanisms", Ventura California, March 1997.
- "Synthesis, Characterization, and Reactivity of bis(ethylenediamine)cobalt(III) Complexes Coordinated by Phenylurea Ligands." Departmental Seminar, Western Kentucky University, Spring, 1996.
- "A Quantitative use of Fe-57 Mossbauer Spectroscopy- The Determination of Amorphous and Crystalline Ferric Phosphate in Commercial Samples." Kentucky Academy of Sciences, Frankfort, KY, November, 1996.
- "Collaborative Writing With Undergraduate Students." 1994 Conference on College Composition and Communication, Nashville, TN. March, 1994.
- "The Kinetics and Mechanisms of Carbon/Sulfur Cleavage in a Thioether Ligand Coordinated to Cobalt(III)." ACS Southeastern Regional Meeting, Johnson City, TN, October 19, 1993.
- Communication Across the Curriculum Participant, Berea College, 1991-1993.
|
Year/Term |
Name |
Project |
|
Fall 1999 |
Pearl Smith & Sanjeewa Goonasekera |
Measuring the Rates of Acid Hydrolysis of Cobalt(III) Complexes Ligated by Phenylurea Ligands |
|
Summer 1999 |
Alison Anderson |
Synthesis of Cobalt(III) Complexes Coordinated by Thiourea Ligands |
|
|
Nicholas Ndiege |
Base Hydrolysis of Cobalt(III) Complexes Coordinated by Thioether Ligands Containing Alkyl Tails |
|
|
Annelie Bergquist |
Using a Spectroscopic Technique to Monitor Soil Nitrate in the Berea College Community Gardens |
|
Fall 1998 |
Christina Likirdopulos & Andrea Carter |
Converting Perchlorate Salts of Cobalt(III) Complexes Coordinated by Phenylurea Ligands into Trifluoromethanesulfonato Salts |
|
Summer 1998 |
Pearl Smith & Robert Ross |
Attaching Amino Acids to Cobalt(III) Cages |
|
|
Joe Smith |
Preparation of a Nickel(II) Precursor to Prepare Two Tailed Surfactants |
|
|
Samuel Asem |
Reducing Nitro Groups on Cobalt(III) Cage Complexes Using Tin as a Reductant |
|
|
Sanjeewa Goonasekera |
Differential Pulse Characterization of Cobalt(III) Cage Complexes |
|
Short Term 1998 |
Andrea Carter and Tamilyn Ingram |
Preparation of Quadridentate Ligands Using Cobalt(III) Complexes as Templates |
|
|
Thomas Bentley |
Synthesis of Thioether Ligands |
|
|
Slava Kichka |
Base Hydrolysis of Monodentate Thioether Ligands Coordinated to Cobalt(III) |
|
|
Adria Bentley & Ariel Drogin |
Base Hydrolysis of the Pentaammine(dimethyl sulfide)cobalt(III) Ion- A Reinvestigation |
|
Summer 1996 |
Denny Marshall |
Analysis of High Oil Corn Using GC-MS |
|
|
Anne Kinton |
Loss of Carbonyl From a High Valent Osmium Complex |
|
|
Hershel Jude |
Studying the Reaction of Super Glue with Wood Oils Using FTIR |
|
|
Irina Gagua and Janet Akande |
Measuring the Rates of Acid Hydrolysis of Cobalt(III) Complexes Ligated by Phenylurea Ligands |
- Summer1995
Anastasi Coots, L. Nelson Elam, Jun Xu, Angie Carrier (Agriculture), Joni
Norris,Pele Okullo
- Short Term1995
Laura Bertram, Robert Little
- Summer or Independent Study1994
Li Jing Sun, Joseph Bogale, Tianpei Xin, Jason Swango, Sisay Gebrekidan, Mike
Clark, Charlotte Mundy (Agriculture)
- Short Term 1994
John Mansfield (Biology), Li Jing Sun, Liwen Liu, Linda Opundo (Physics), Mike
Clark, Nelson Elam, Selina Stambaugh, Pele Okullo, Joseph Bogale, Laura
Bertram, Jason Swango, Sisay Gebrekidan
- Summer1993
Liwen Liu, Shing Mirn Lee (Mathematics/Economics), Miranda Prewitt, Regina
Hicks, Tianpei Xin (with Larry Blair)
- Short Term 1993
Thomas Demond (Agriculture)
- Fall 1992
Bereket Berhane (Physics/Mathematics)
- Summer1992
Li Jing Sun, Regina Hicks, Billy Helton
- Spring 1992
Koorosh Zaerpoor (Physics/Mathematics)
- Summer 1991
Regina Hicks, J. Kiely Starnes
- Short Term 1991
Greg Reeder, Billy Helton, Alisa Perkins, Greg Reeder, Manuel San (Biology),
Anton Jones
- Fall Term 1990
Angela Fultz , Craig Thompson
- Summer 1990
Matthew Saderholm, Larry Parsons Jr., Lee Ann Smith, Billy Helton, Anton Jones,
Russell Davis
- Short Term Independent Study 1990
Amy Ellis, David Olaker
- Spring Term 1990 (at University of Dayton)
Timothy Doerr, Michael Stabb
Dr. Lee E. Roecker
Berea College, CPO 1966
Berea, KY 40404
Phone: (606) 985-3318
WEB page updated on 27 JAN 2000 by Lee E. Roecker
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