Faculty

Jenine Maeyer

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First Name: 
Jenine
Last Name: 
Maeyer
Official Title: 
Senior Lecturer
Additional Titles: 
Director, General Chemistry Laboratory
Contact Information
Office Location: 
Room 152, Cret Building
Email: 
jmaeyer@sas.upenn.edu
Phone: 
215-746-6315
Education: 

Ph.D. in Chemistry

University of Arizona, Tucson, AZ

 

B.S. in Chemistry and Mathematics

The College of William and Mary, Williamsburg, VA

Jeffrey D. Winkler

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First Name: 
Jeffrey D.
Last Name: 
Winkler
Official Title: 
Merriam Professor of Chemistry

Organic Chemistry 

Contact Information
Office Location: 
449 Chemistry Bldg.
Email: 
winkler@sas.upenn.edu
Phone: 
(215) 898-0052
Fax: 
(215) 573- 6329
Admin Support: 
Education: 
  • A.B. Harvard College (1977)
  • M.A., M.Phil., Ph.D. Columbia University (1981-83)
Research Interests: 

New Synthetic Pathways Based on the Intramolecular Dioxenone and Vinylogous Amide Photocycloaddition Reactions

We have developed these methods and have applied them to the first total syntheses of several molecules of biological importance, including manzamine A, 1, saudin, 2 , and ingenol, 3.

 

Total Synthesis of Manzamine-Related Structures

Current efforts in our laboratory are focused toward the synthesis of nakadomarin, 4, a structurally complex hexacyclic alkaloid that displays a range of promising biological activities including cytotoxic activity against murine lymphoma L1210 cells, inhibitory activity against cyclin dependent kinase 4, and anti-microbial activity against a fungus and a Gram-positive bacterium. We have also demonstrated that manipulation of the structure of 1 via Grubbs metathesis leads to the formation of novel structures, i.e., 5, with antibacterial properties comparable to those of ciprofloxacin. Finally, we have embarked on a program directed toward the synthesis of neokauluamine, 6, a dimeric manzamine with highly potent immunosuppressive properties. 

 

Transformations Using Organic Photochemistry

We have recently discovered a novel approach to the synthesis of substituted thiophenes 8 from arylsulfide enone precursors 7. The study of the mechanism of this unusual transformation (9 is a byproduct) as well as its application to the synthesis of more complex structures is currently underway in our laboratory.

 

Development of Novel Inhibitors of Hedgehog Signaling Based on Cyclopamine

Aberrant activation of the Sonic Hedgehog (Hh) signaling pathway has been associated with numerous malignancies in the brain, breast, pancreas and other organs. In vivo evidence suggests the antagonism of excessive Hh signaling may provide a route to unique mechanism-based therapies for the treatment of cancer. The steroidal alkaloid cyclopamine 10 suppresses the Hh signaling pathway, and has recently been been shown to be effective in the treatment of cancer using a variety of mouse models. Human cells are also sensitive, supporting the promising use of this natural product. However, the metabolic instability of cyclopamine precludes its clinical use. A significant demand exists for more stable cyclopamine-like structures. This project is directed toward the synthesis of cyclopamine-like structures, i.e., 11, from readily available metabolically-stable steroidal precursors, i.e., estrone.

 

Total Synthesis of Cortistatin A

The development of specific anti-angiogenic agents that could serve as anticancer chemotherapeutic agents is an important goal. In 2006, Kobayashi isolated the cortistatins from the marine sponge Corticium simplex. Cortistatin A 12 is the most active member of this family. It exhibits antiproliferative activity against human umbilical vein endothelial cells at nM concentrations. The total synthesis of the cortistatins and designed materials with cortistatin-like properties is one of the goals of our laboratory.

Patrick J. Walsh

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First Name: 
Patrick J.
Last Name: 
Walsh
Official Title: 
Professor of Chemistry

Inorganic Chemistry, Organic Chemistry, Chemical Catalysis

Contact Information
Office Location: 
3001 IAST
Email: 
pwalsh@sas.upenn.edu
Phone: 
(215) 573-2875
Fax: 
(215) 573-6743
Admin Support: 
Education: 
  • Advisor Prof. K. Barry Sharpless
  • 1986 B.A. in Chemistry, University of California, San Diego
  • 1991 Ph.D in Chemistry, University of California, Berkeley
  • 1991-1994 NSF Postdoctoral Fellow Postdoctoral, The Scripps Research Institute
Research Interests: 

Research in the Walsh group merges the fields of catalysis and organic and inorganic synthesis with the goal of achieving new catalytic asymmetric transformations for the synthesis of chiral building blocks. The transformations we have chosen to study are asymmetric C-C and C-O bond forming reactions, because construction of these bonds lies at the very heart of organic synthesis. We are also interested in the development of tandem reactions that combine several steps in a single reaction vessel. By introducing tandem reactions, we can increase synthetic efficiency while reducing the number of purification steps necessary. 

 

Shown below are examples of tandem reactions developed in the Walsh group:

 

We are also interested in reaction mechanisms, which gives us the opportunity to synthesize some interesting catalysts. Shibasaki's M3(THF)n(BINOLate)3Ln (Ln = lanthanide, M = Li, Na, K) catalyst are among the most efficient known in asymmetric catalysis. We have studied the structure and reactivity of these amazing catalysts, one of which is shown below.4-6 

We are also interested in structural organozinc chemistry. The first example of zinc coordinated to C-C double bond was recently reported from our group.7 

In 2006 the Walsh group crystallographically characterized about 40 compounds, most of which contained metals.

Michael R. Topp

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First Name: 
Michael R.
Last Name: 
Topp
Official Title: 
Professor of Chemistry

Physical Chemistry 

Contact Information
Office Location: 
249 N, Lab: 240 N
Email: 
mrt@sas.upenn.edu
Phone: 
(215) 898-4859
Admin Support: 
Education: 
  • B.Sc. Sheffield University (1966) - Haworth Medal winner
  • Ph.D. University College London and the Royal Institution of Great Britain (1969)
  • Member of Technical Staff, Bell Labs, (1969-71)
  • IBM Research Fellow, Pembroke College, Oxford (1971-73)
Research Interests: 

Conformational Relaxation in Isolated Molecular Clusters

When molecules become electronically excited, the rearrangement of electronic charge can precipitate many types of relaxation processes. To probe details of such events, one can employ isolated molecular clusters consisting of only a few hydrogen-bonded molecules. One particularly interesting case is the cluster involving a Coumarin 151 molecule bonded to a water dimer. Two different structures have been identified in the ground state, as shown below.

 

 

Recent experiments have shown that the species shown on the left here is unstable in the excited state, and relaxes to that shown on the right on a picosecond or nanosecond time scale depending on the available energy. This corresponds to movement of the water dimer by ~10Å from one side of the molecule to another, following and yet the activation energy is only 60 cm-1. Such conformational changes have been studied by a combination of fluorescence and infrared double resonance techniques in conjunction with ionization and mass resolution.

 

Hydrogen-Bonded Molecular Dimers

 

Hydrogen-bonded dimers present important opportunities to study short-range intermolecular interactions, including modification of the electronic structure, and corelated proton or hydrogen atom transfer. Molecules such as the dimer of 4-Amino-N-methylphthalimide, shown here, reveal dramatic changes in their infrared spectra between the ground and excited states. The simple ground-state ground-state infrared spectrum reflects the high symmetry of the ground state. On the other hand, the much more complex excited-state spectrum shows evidence for a loss of symmetry resulting from changes in the acid-base properties of NH2 and >C=O groups, which may result in proton transfer across the intermolecular hydrogen bonds. These types of strongly bonded dimers are different from many other dimer systems studied so far, because both their electronic and vibrational spectra are highly structured, despite the large increase in binding energy upon electronic excitation. Femtosecond-domain experiments are planned, to follow in real time the changes in vibrational spectra, which will provide further insights into the reasons for their complexity in the excited state.

 

 

Ultrafast Electronic Relaxation of Hydrogen-Bonded Molecules Studied by Femtosecond Pump-Probe Spectroscopy

 

Femtosecond pump-probe experiments allow us to observe the time evolution of the first events following pulsed laser excitation, including motions in the first coordination shell of a hydrogen-bonded molecule in fluid solution. New pump-probe experiments involving the detection of ultrashort-lived fluorescence have explored spectroscopic changes of aminophthalimide molecules in hydrogen-bonding solvents on a time scale more than 10 times faster than existing data for fluorescence Stokes shifts. Both fluorescence upconversion and pump-probe methods are being used to investigate ultrafast energy transfer processes in complex molecules, in collaboration with the Regional Laser and Biomedical Technology Laboratories at Penn.

Joseph Subotnik

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First Name: 
Joseph
Last Name: 
Subotnik
Official Title: 
Professor of Chemistry

Physical and Theoretical Chemistry

Contact Information
Office Location: 
268 Cret wing
Email: 
subotnik@sas.upenn.edu
Phone: 
215-746-7078
Admin Support: 
Education: 

B.A. Harvard University, 2000

Physics and Math (summa cum laude)


Ph.D.  UC Berkeley, 2006  Biophysics

 

NSF International Research Fellow (2007 -2009), Tel-Aviv

Postdoctoral Fellow, Northwestern University (2009-2010)

Research Interests: 

Research in the Subotnik group focuses on the intersection of static quantum chemistry methods (especially for excited states) with nonadiabatic dynamics methods (specifically surface hopping). The focus is quantifying electron transfer, energy transfer, and electronic relaxation. Applications are to almost all photo-induced processes!

Amos B. Smith III

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First Name: 
Amos B.
Last Name: 
Smith III
Official Title: 
Rhodes-Thompson Professor of Chemistry

Organic Chemistry

Contact Information
Office Location: 
440N
Email: 
smithab@sas.upenn.edu
Phone: 
(215) 898-4860
Fax: 
(215) 898-5129
Admin Support: 
Education: 
  • B.S.- M.S. Bucknell University (1966)
  • Ph.D. Rockefeller University (1972)
  • Associate, Rockefeller University (1972-73)
Research Interests: 

Smith's research interests encompass three diverse areas: natural product synthesis, bioorganic chemistry and materials science. To date, more than 90 architecturally complex natural products having significant bioregulatory properties have been prepared in his Laboratory. In addition, Smith, in collaboration with Ralph Hirschmann, has achieved the design and synthesis of non-peptide peptidomimetics of neuropeptideic hormone/transmitters and protease enzyme inhibitors and, also with Stephen Benkovic (Penn State), haptens for the production of catalytic antibodies capable of peptide bond formation. At Monell, in collaboration with Peter Jurs (Penn State), he pioneered the use of computerized pattern recognition techniques for the analysis of primate chemical communication. Collaborative programs at the LRSM include the chemistry and physics of novel liquid crystals and the fullerenes. To date Smith research achievements have been reported in more than 500 peer reviewed publications.

Emmanuel Skordalakes

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First Name: 
Emmanuel
Last Name: 
Skordalakes
Official Title: 
Associate Professor, Gene Expression and Regulation Program

Biological Chemistry 

Additional Titles: 
Wistar Institute Associate Professor of Chemistry
Contact Information
Email: 
skorda@wistar.org
Phone: 
(215) 495-6884
Fax: 
(215) 573-9889
Education: 
  • 2001-2006: Postdoctoral Fellow, University of California, Berkeley
  • Ph.D.: Imperial College, University of London (2000)
  • M.Sc.: University College London (University of London) (1992)
  • B.Sc.: Anglia Ruskin University, Cambridge (1991)
Research Interests: 

 

The focus of my research lies with protein nucleic acid assemblies that participate in the replication and maintenance of eukaryotic chromosome ends, called telomeres. Telomeres protect chromosome ends from gradual length erosion, prevent end-to-end fusions and recombination, and promote proper chromosome partitioning during meiosis. Telomere length deregulation and telomerase activation are early and perhaps necessary steps in cancer cell evolution. Furthermore, telomerase and telomere dysfunction are thought to contribute to replicative senescence and programmed cell aging. Despite these fundamental roles in maintaining genome integrity and cell fate, surprisingly little is known about the molecular basis of telomere synthesis by telomerase. We are interested in elucidating the mechanism of telomere replication by telomerase and understand how telomere and telomerase binding proteins regulate telomerase activity and protect chromosome ends. The lab primarily uses structural methods coupled with biophysical and biochemical techniques to study the above systems.

Telomerase Function

Telomere replication is mediated by telomerase, an RNA dependent DNA polymerase structurally similar to retroviral reverse transcriptases and viral RNA polymerases. Biochemical studies on telomerase for more than two decades have provided a wealth of information regarding telomerase function and substrate specificity. Despite this information, the biophysical mechanisms underlying telomerase architecture and function are poorly understood. Our goal is to further elucidate the molecular basis of telomere replication by telomerase using structural and biochemical approaches. The information generated here should provide novel insights into the basic mechanisms of telomere replication and length homeostasis. It will further enrich our understanding of the mechanism of DNA replication by polymerases in general. It will provide a framework to design small molecule inhibitors of telomerase that may be of therapeutic value for cancer and other diseases associated with cellular aging.

Telomerase Regulation

In recent years, a number of factors essential for telomerase regulation and telomere maintenance have been identified. The method by which telomerase and associated regulatory factors physically interact and function with each other to maintain appropriate telomere length is poorly understood. Structural and biochemical characterization of these factors, both in isolation and in complex with one another will facilitate our understanding of how the proper function of these factors impacts telomerase function and cell proliferation.

Eric J. Schelter

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First Name: 
Eric J.
Last Name: 
Schelter
Official Title: 
Associate Professor of Chemistry

Inorganic and Materials Chemistry

Contact Information
Office Location: 
3003 IAST
Email: 
schelter@sas.upenn.edu
Phone: 
(215) 898-8633
Fax: 
(215) 573-6743
Twitter: 
@SchelterGroup
Admin Support: 
Education: 
  • B.S. Michigan Technological University (1999)
  • Ph.D. Texas A&M University, Advisor: Kim R. Dunbar (2004)
  • Glenn T. Seaborg Postdoctoral Fellow, Los Alamos National Laboratory (2004-2005)
  • Director's Postdoctoral Fellow, Los Alamos National Laboratory (2006)
  • Frederick Reines Postdoctoral Fellow in Experimental Sciences, Los Alamos National Laboratory (2006-2009)
Research Interests: 

 

Projects in the Schelter Group involve inert atmosphere/Schlenk line synthesis of inorganic and organometallic complexes. Rigorous characterization of new compounds is achieved through X-ray crystallography, NMR, FTIR, and UV-Visible absorption spectroscopies, electrochemistry and magnetic susceptibility studies. Current projects are focused on the chemistries and electronic structure effects of the lanthanides, uranium and main group elements

Advanced Rare Earths Separations Chemistry

The rare earth elements: La-Lu, Y and Sc are used in critical renewable energy applications including wind turbine generators and hybrid electric vehicle batteries. These modern applications require pure rare earth elements that must be separated from their composite mineral sources. The Peoples Republic of China currently holds ~97% of the international rare earths market comprising nearly all aspects of the (environmentally taxing) supply chain. To develop other sources of rare earths and reduce the environmental impact of their isolation, there is a clear need for new separations chemistry that reduces the cost of industrial-scale rare earths separations. This project seeks to develop a totally new extractant strategy by harnessing the physicochemical distinctiveness of certain high-value rare earths. New designer rare earth extractants will enable selective separations chemistry for these technologically critical elements.

 

Capturing Heavy-Fermion Type Electron Correlations in Molecular Complexes

The intermetallic heavy-fermion materials, comprising intermediate valence f-elements such as cerium, are characterized by exotic emergent phenomena including unconventional superconductivity. Recent results on these materials suggest a common energy scale for the emergence of the superconducting state, dependent on the local magnetic interaction of f-moments with conduction electrons. Local electron correlations are also believed to underpin the high Tc superconductivity of other families of materials. Parallel studies in molecular chemistry have begun to show inorganic and organometallic complexes are capable of exhibiting the same type of mixed-valency and correlations found in the heavy-fermion materials.

This project will generalize the requirements for emergence of Kondo-like phenomena in magnetically-dilute molecular complexes. New materials will be synthesized from fundamental units of electron correlation to three-dimensional molecular phases.

 

 

 

Exploring the Inverse Trans Influence in the Chemistry of Uranium

Antithetical to the trans influence in transition metal chemistry, which results in a weakening of metal-ligand bonds trans to strongly-bound groups, is the inverse trans influence in the chemistry of the actinides. Semi-core p-orbital mixing with valence d- or f-orbitals gives rise to the influence, however, the presence of both orbital types in the actinide valence shell precludes its simple description. The large thermodynamic stability of the ubiquitous linear, trans-dioxo uranyl cation, UO22+ is one important consequence of this influence.

This project will develop new complexes in varying geometries and coordination environments to systematically study the inverse trans influence in the structural chemistry of uranium. These results will have direct relevance to the bio-remediation of actinide contaminated ground waters, for which the thermodynamic driving force of the influence plays an important role.

Jeffery G. Saven

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First Name: 
Jeffery G.
Last Name: 
Saven
Official Title: 
Professor of Chemistry

Biological and Theoretical Physical Chemistry

Contact Information
Office Location: 
266 Cret, Lab 261 Cret
Email: 
saven@sas.upenn.edu
Phone: 
215-573-6062
Fax: 
215-573-2112
Admin Support: 
Education: 
  • BA, New College of Florida
  • PhD, Columbia University & University of Wisconsin
  • NSF Postdoctoral Fellow in Chemistry, University of Illinois, Urbana-Champaign, 1993-1995. Postdoctoral Research Associate, University of Illinois, Urbana-Champaign, 1995-1997
Research Interests: 

Computationally designed protein complex containing a nonbiological cofactor, designed and studied in collaboration with the DeGrado and Therien groups in the Department of Chemistry. On the left is the computationally designed protein scaffold (magenta) and two abiotic porphyrin cofactors (yellow). On the right is a model of the computationally designed sequence and structure.

 

Our research interests involve theoretical chemistry, particularly as it applies to biopolymers, macromolecules, condensed phases, and disordered systems. We are developing computational methods for understanding and designing molecular sytems having many physical and chemical degrees of freedom. Molecular simulation techniques are used both to study molecular systems in detail and to test and illustrate our theories. 

 

A current thrust of the group involves developing computational tools for understanding the properties of protein sequences consistent with a chosen three-dimensional structure. The group works closely with experimental groups at Penn and at other universities; some group members are involved in joint theoretical/experimental projects. Recent projects involve the design of soluble and membrane bound proteins, discerning the origins of conservation in naturally occurring proteins, biomolecular simulation, and the design of nonbiological folding molecules.

Andrew M. Rappe

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First Name: 
Andrew M.
Last Name: 
Rappe
Official Title: 
Blanchard Professor of Chemistry

Physical and Theoretical Chemistry

Additional Titles: 
Professor of Materials Science and Engineering
Co-Director, Pennergy
Contact Information
Office Location: 
264 Cret, Lab: 263, 265, 267, 268 Cret
Email: 
rappe@sas.upenn.edu
Phone: 
(215) 898-8313
Fax: 
(215) 573-2112
Admin Support: 
Education: 
  • B.A. Chemistry and Physics, Summa Cum Laude, Harvard University (1986)
  • ONR Graduate Fellow, Massachusetts Institute of Technology (1986-1989)
  • JSEP Graduate Fellow, Massachusetts Institute of Technology (1990-1992)
  • Ph. D. Physics and Chemistry, Massachusetts Institute of Technology (1992)
  • IBM Postdoctoral Fellow, University of California at Berkeley (1992-1994)
  • Assistant Professor of Chemistry, University of Pennsylvania (1994-2000)
  • Associate Professor of Chemistry, University of Pennsylvania (2000-2006)
  • Professor of Chemistry, University of Pennsylvania (2006-present)
  • NSF CAREER Award (1997-2001)
  • Alfred P. Sloan Foundation Fellow (1998-2000)
  • Dreyfus Teacher-Scholar Award (1999-2004)
Research Interests: 

 

My research group creates and uses new theoretical and computational approaches to study complex systems in materials science, condensed-matter physics, and physical chemistry.

 

We look for new phenomena that occur when different components are brought together. For example, we examine molecules adsorbing on metal surfaces, in order to understand the effect of surface composition and structure on preferred adsorption sites, dissociation pathways, and vibrational dynamics. We also study how the compositions of oxide solid solutions lead to Angstrom-scale chemical structure, nanometer scale structural disorder, and long-range ferroelectric and piezoelectric properties. These studies find real-world applications in catalysis, corrosion, SONAR, fuel cells and other important technologies. Whenever possible, we model systems analytically, in order to extract general principles and simple pictures from complex systems. We recently derived general expressions for the vibrational lifetimes of molecules on surfaces, revealing the dependence of lifetime on molecular coverage and arrangement. Our recent exploration of quantum stress fields has helped to link chemical and mechanical effects in materials.

 

We are constantly developing methods for computing new properties, and for making quantum-mechanical calculations more accurate and more efficient. We tailor computational algorithms to maximize performance on modern computing platforms such as Beowulf clusters. Wherever possible, we also model systems analytically, in order to extract general principles and simple pictures from complex systems. This combination of theoretical and computational tools enables us to identify new phenomena in complex systems, like multicenter bonds between methyl radicals and the rhodium surface. ( See figure below )

Converting the 5d wavefunction of gold to a smoother pseudowavefunction results in a dramatic reduction in the required basis set size for converged calculations.

Department of Chemistry

231 S. 34 Street, Philadelphia, PA 19104-6323

215.898.8317 voice | 215.573.2112 fax | web@chem.upenn.edu

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