Department of Chemistry

Byron L. Bennett

Assistant Professor of Chemistry

Ph.D. Inorganic – Organometallic Chemistry University of Wyoming – 1997

Research area: Inorganic Chemistry, Organometallic Chemistry

Student experience required for research: Chem 111, Chem 112, enrolled in Chem 301

Student experience gained from research: Synthetic methods, NMR, air-sensitive techniques, mass spectrometry, IR, UV-Vis, Cyclic voltametry

Ideal preparation for: Chemical industry, pharmaceuticals, medical research, preparation for graduate school in chemistry or for professional school

Research Description

Chemistry in Fluorocarbon Solvents: Fluorous Ligand Synthesis and Coordination

Fluorocarbon media & FBS (Fluorous Biphasic Systems) can be utilized in separation schemes for environmental benefit and improvement of industrial process efficiency (precious metal catalyst recovery).

Homogenous catalysts often result in higher reactivity than their heterogeneous counterparts and thus represent an important goal in process design. FBS represents one of the recent design advancements for homogeneous catalysis. This type of system employs combinations of hydrocarbon and fluorocarbon solvents that exhibit temperature dependent miscibility. The key to construction of a functional FBS catalytic process is synthesis of a fluorocarbon soluble transition metal catalyst.

2,2'-bipyridine complexes of Ru (II) and Re(I) have been identified as potential photochemical or electrochemical catalysts for CO2 reduction. Modification of several 2,2'-bipyridines (bpy) with fluorocarbon chains attached in the 4/4' position has been completed (see publication # 2) by our group (see scheme below).

Initial studies of the photochemical catalytic activity of the Re(I) complexes (formula fac-(bpy)Re(CO)3Cl) in CO2 reduction to CO in the DMF/TEOA media (original report ? 1980's) indicate that the substituents do not inhibit the activity of the Re(I) center in comparison to the simple unmodified bipyridine complex (comparison of both TOF and TON). Implementation of perfluorocarbon as a co-solvent in the reaction mixture is underway.

Novel 2,2'-bipyridine Pt(II) Complexes: Cisplatin Analogues

A collaborative project with Dr. Alok Bhushan (Department of Biomedical and Pharmaceutical Sciences -ISU) focuses on the preparation of 2,2'-bipyridine compounds of Pt(II) and evaluation of their function as effective cytotoxins for cancer tissue. Cisplatin is one of the original chemotherapeutic agents for cancer treatment and has a remarkably simple structure shown below. The simplicity severely limits its selectivity such that all rapidly growing tissue is targeted by the drug, tumor and non-tumor alike. A limitation of side effects would include an improvement in selectivity and decrease in dose. Our work involves the preparation of complexes which feature the replacement of the NH3 groups with 2,2'-bipyridine. Synthesis of 4,4'-disubstituted-2,2'-bipyridines is carried out implementing substituents of various steric size and shape. The modified bipyridine compounds function as ligands for Pt(II) readily forming complexes of diverse stereoelectronic character. The complete preparative procedures (nucleophilic substitution processes leading to the ligands and the coordination chemistry) are completed within our group. Dr. Carper has evaluated our preliminary series of Pt complexes and found significant cytotoxicity for the broad class of compounds when compared to cisplatin. By way of example the Pt complex shown below is 100 times more lethal than cisplatin in a breast cancer cell line (see publication #1). A variety of cancer cell lines including Head/neck, breast, lung, prostate, and testicular have been under investigation. In addition to the collogenic assay results, flow cytometry data indicates that the individual complexes block the cell cycle at different phases for each cell line. Upon consultation with the biochemical team our group prepares complexes to suit anticipated research paths and hypotheses.

Two other projects are underway:

Macrocyclic Design: Difunctional 4-pyridyl ligands and Transition Metals – Selective Detection of Small Molecules by Emission Spectroscopy

Fluorous 1,10-Phenanthroline Synthesis: Potential Liquid Crystalline Materials

Selected Publications:

1. Kyler E. Elwell, Casey Hall, Shweta Thaker, Yvonne Giraud, Byron L. Bennett, Chulsung Bae, Stephen W. Carper "A fluorine containing bipyridine Cisplatin analog is more effective than Cisplatin at inducing apoptosis in cancer cell lines", Bioorganic & Medicinal Chemistry, 2006, 14(24), 8692.

2. Byron L. Bennett, Kathleen A. Robins, Ryan Tennant, Kyler Elwell, Felice Ferri, Inna Bashta, and Grant Aguinaldo, "Fluorous Modification of 2,2'-Bipyridine", Journal of Fluorine Chemistry, 2006, 127(1), 140.

3. David W. Emerson, Byron L. Bennett, Spencer M. Steinberg, "A One Pot Synthesis of Bis(?-Fluoroalkyl) and Alkyl Disulfides", Synthetic Communications, 2005, 35, 631.

4. Vincent J. Catalano, Byron L. Bennett, Mark A. Malwitz, Renante L. Yson, Heidi M. Kar, Stamatis Muratidis and Stephen J. Horner, "Metallocryptands: Host Complexes for Probing Closed-Shell Metal-Metal Interactions" Comments on Inorganic Chemistry, 2003, 24(1), 39.

5. Byron L. Bennett, Shannon White, Brittany Hodges, Dane Rodgers, Ade Lau, and Dean M. Roddick "(Fluoroalkyl)phosphine Complexes of Nickel(0) and Cobalt(I)" Journal of Organometallic Chemistry 2003, 679(1), 65.

6. Shannon White, Eric W. Kalberer, Byron L. Bennett and Dean M. Roddick, Synthesis, Structure, and Characterization of a Bridging Ethylidene (Perfluoroalkyl)phosphine Platinum Complex, Organometallics, 2001, 20, 5731.

7. Tibor Soos, Byron L. Bennett, Drew Rutherford, Luis P. Bartel-Rosa, and J. A. Gladysz, "Synthesis, Reactivity, and Metal Complexes of Fluorous Triarylphosphines of the Formula P(p-C6H4(CH2)3(CF2)n-1CF3)3 (n = 6, 8, 10)" Organometallics, 2001, 20, 3079.

8. Vincent J. Catalano, Byron L. Bennett, Stamatis Muratidis, and Bruce C. Noll, "Unsupported Pt(0) Tl(I) Bonds in the Simple [Pt(PPh2Py)3Tl]+ Complexes", Journal of the American Chemical Society, 2001, 123, 173.

9. Vincent J. Catalano, Byron L. Bennett, Renante L. Yson, and Bruce C. Noll, "Synthesis and Characterization of Pd(0) and Pt(0) Metallocryptands Encapsulating Tl+ Ion", Journal of the American Chemical Society, 2000, 122, 10056.

10. Christian Rocaboy, Drew Rutherford, Byron L. Bennett, and J. A. Gladysz, "Strategy and Design in Fluorous Phase Immobilization: A Systematic Study of the Effect of "Pony Tails" (CH2)3(CF2)n-1CF3 Upon Partition Coefficients of Benzenoid Compounds", Journal of Physical Organic Chemistry, 2000, 13, 596.


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