Nanoscale Science and Engineering

Special Seminar: Eleni Katifori, MPI-Goettingen

Thu, 2013-01-17 10:00
Speaker: 

Dr. Eleni Katifori

Max Planck Institute - Goettingen

 

The evolution of leaf vasculature: deciphering the design of optimal loopy architectures

 

Host: Douglas Jerolmack (Earth and Environmental Sciences)

Location: 

Lynch Lecture Hall

 

Virgil Percec

Photo: 
First Name: 
Virgil
Last Name: 
Percec
Official Title: 
P. Roy Vagelos Professor of Chemistry

Organic, Supramolecular and Macromolecular Chemistry

Contact Information
Office Location: 
4003 IAST, Lab: 4160 IAST
Email: 
percec@sas.upenn.edu
Phone: 
(215) 573-5527
Fax: 
(215) 573-7888
Admin Support: 
Education: 
  • B.S. 1969 Department of Organic and Macromolecular Chemistry, Polytechnic Institute of Jassy, Romania
  • Ph.D. 1976 Institute of Macromolecular Chemistry, Jassy, Romania
  • Postdoctoral July-August 1981 Hermann Staudinger Hause, University of Freiburg, Germany
  • Postdoctoral September 1981 - March 1982 Institute of Polymer Science, University of Akron, U.S.A.
Research Interests: 

Our research group is involved in the elaboration of synthetic methods, strategies and architectural concepts, as well as in the understanding of the fundamental principles that govern the rational design and synthesis of complex molecular, macromolecular, and supramolecular nonbiological systems that exhibit biological functions. Biological systems are employed as models to develop the synthetic architectural motifs and to control their self-assembly and self-organization during the creation of ordered systems. Our research strikes a balance among a diversity of interrelated disciplines, such as organic, bioorganic, macromolecular, and supramolecular synthesis and catalysis, seeking to understand, mimic, and extend Nature's solutions to the design of synthetic functional nanosystems. 

 

Hierarchical folding, supramolecular chirality, nonbiological ionic and electronic channels and nanowires, nanostructured supramolecular membranes, externally regulated drug release mechanisms, enzyme-like catalytic systems, and self-interrupted organic and macromolecular synthesis are examples of new concepts that are under investigation. Central to the capacity of biological molecules to perform critical functions is their ability to form highly organized and stable 3-D structures using a combination of molecular recognition processes. Therefore, the combinatorial libraries of synthetic building blocks required in our strategies consist of combinations of macrocyclic, dendritic, and other primary sequences that are able to fold into well-defined conformations and also contain all the information required to control and self-repair their secondary, tertiary, and quaternary structure at the same level of precision as in biological molecules. To what extent the delicate balance between the structures and functions evolved in Nature during billions of years can be transplanted to synthetic molecules is a fascinating question.

 

Towards these goals, we also develop new synthetic methods for the formation of carbon-carbon and carbon-heteroatom bonds using metal-catalyzed homo- and cross-coupling, radical, and various ionic and ion-radical reactions. Living and non-statistically self-interrupted polymerization methods are elaborated based on these organic reactions. The design of the internal structure of complex single molecules and the elucidation of the reactivity principles induced by the controlled environment confined within a single molecule or supramolecule are actively pursued. This research involves collaborations with structural and computational chemists and biochemists.

Christopher B. Murray

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First Name: 
Christopher B.
Last Name: 
Murray
Official Title: 
Richard Perry University Professor of Chemistry and Materials Science and Engineering

Nanoscale and Inorganic Materials Chemistry

Contact Information
Office Location: 
347N (Chem 73) & 322 (LRSM) MSE
Email: 
cbmurray@sas.upenn.edu
Phone: 
(215) 898-0588
Admin Support: 
Education: 
  • 1985-1988 B.Sc. Honors Chemistry, Summa cum Laude, St. Mary's University, Halifax N.S., Canada
  • 1989 Rotary International Fellow, University of Auckland, New Zealand
  • 1990-1995 Ph.D. Physical Chemistry, Massachusetts Institute of Technology, Cambridge, MA
  • 1995- 2000 Member of research staff, IBM Corp., T. J. Watson Research Center. Established a program in the preparation and characterization of nanomaterials and devices.
  • 2000 - 2006 Manager of the Nanoscale materials and devices department leading development of nanomaterials and exploring self-organizing phenomena for applications in IT.
  • 2007- University of Pennsylvania: Richard Perry University Professor of Chemistry and Materials Science and Engineering.
Research Interests: 

Our research focuses on Materials Chemistry with full participation in both the departments of Chemistry in the School of Arts and Sciences (SAS) and in the Department of Materials Science and Engineering in the School of of Engineering and Applied Sciences (SEAS).

 

Many collective phenomena in inorganic materials have natural length scales between 1 and 50 nm. Thus size control nanometer sized crystals or "nanocrystals" allows materials properties to be engineered. Nanocrystals display new mesoscopic phenomena found in neither bulk nor molecular systems. For example, the electronic, optical and magnetic properties semiconductors and magnetic nanocrystals strongly depend on crystallite size. Excited by the potential of these nanocrystal materials our mode of operation has been to develop leading synthetic methods and to push the resulting materials toward technology demonstrations. We try to blend the perspective of academic chemistry and materials science with technological perspective that I developed in over a decade of work in industrial research. We hope this mix of influences will help to align opportunities for applications with broader understanding of nanomaterials. Materials chemistry that embraces and harnesses these principles of self-assembly is at the frontier of materials science and become one of its cornerstones within our generation. Key challenges to the advance of this field will be met by advancing synthetic design, improved analytical tools and perhaps through forethought of environmental health and safety issues. Share in efforts to meet these challenges and thus influence the evolution of both materials science and chemistry. 

Other Affiliations: 

Zahra Fakhraai

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First Name: 
Zahra
Last Name: 
Fakhraai
Official Title: 
Associate Professor of Chemistry

Physical Chemistry, Materials Chemistry, Nanoscale Science and Engineering

Contact Information
Email: 
fakhraai@sas.upenn.edu
Admin Support: 
Education: 
  • B.Sc. Physics, Sharif University of Technology, Iran 1999
  • M. Sc. Physics, Sharif University of Technology, Iran 2001
  • Ph.D. Physics, University of Waterloo, 2007
  • Post-Doctoral associate, Chemistry, University of Toronto, 2007-08.
  • NSERC Post-Doctoral Fellow, Chemistry, University of Wisconsin-Madison, 2009-11.
Research Interests: 

Our group is interested to study the effect of nano-confinement on structure, dynamics and other properties of materials. Materials behave differently on surfaces, interfaces or small length scales compared to their bulk properties.  Understanding such differences are crucial in many technological applications where materials are constrained in nanometer size spaces, such as organic electronics, polymer applications and drug delivery. One can take advantage of such difference to produce novel materials, such asexceptionally stable glasses or harvest light for various applications. In biological systems, most of the dynamics happens in nanometer size proximity of surfaces and interfaces, and understanding the properties in confinement is a key in predicting function. We focus our efforts on understanding the origins of such modified properties on a fundamental level as well as possible application of such phenomena in producing novel materials or experimental tools.


Enhanced Mobility at the Surface of Polymeric and Organic Glasses: 

 

We study the properties of glasses at the air/glass interface. Our studies show that below the glass transition temperature, where the bulk of the material is in an out of equilibrium state, the interfacial dynamics are many orders of magnitude faster that the bulk dynamics. As a result a layer close to the interface maintains equilibrium properties. We study the dynamics of this layer, its thickness, and its effect on the properties of the underlying glass. The interfacial layer can strongly modify properties of amorphous materials in nanometer length scales. They also allow one to produce near-equilibrium structures at temperatures well below bulk glass transition temperature, through physical vapor deposition.


Exceptionally Stable Glasses: 


 

The enhanced mobility of the interfacial layer allows us to produce near-equilibrium glasses at temperatures well below the bulk glass transition temperature, Tg, by means of physical vapor deposition (PVD). Exceptionally stable glasses are formed when the substrate temperature during PVD is maintained just below the glass transition temperature. We study the morphology and the kinetics of PVD films during formation and their relationship to the final properties of the stable glass. These studies provide information on mechanisms of rapid aging below Tg and stable glass formation. We also investigate exceptional material properties of these glasses and the role of the chemical structure in these properties such as the optical birefringence and electronic properties.


 

Novel Emergent Optical Properties in Disordered Nanoparticle Clusters: 


 

Using simple synthetic routs we can produce dielectric core-gold shell nanoparticles decorated with randomly packed nanoparticles of various shapes and sizes. Spiky nanoparticles are a good example of such nanoparticles. Broadband and tunable structure of spiky gold nanoshells makes them ideal for various applications such as enhanced Raman scattering, temperature and index sensing and sensors for biological and light harvesting applications. Exceptional properties, such as higher order quadrupoloar scattering and magnetic dipole plasmons in these nanoparticles are due to inherent disorder in their structure and random packing arrangements. We explore optical properties of these nanoshells, using various theoretical and experimental tools. We also develop new techniques that allow us to study properties of meta materials formed from these types of particles.

 


Surface Mediated Self-assembly of Amyloid Aggregrates: 


 

Surface self-assembly provides an alternative pathway for amyloid aggregation that is not available in bulk solutions. We us high-resolution atomic force microscopy and other imaging techniques to study the adhesion and diffusion of peptides on various surfaces and their role in facilitating amyloid fibril formation through self-assembly routs. We also use our exceptional capabilities in high-resolution imaging to study the conformation of amyloids formed under various conditions in aqueous conditions.

Selected Publications: 

1.     T. Liu, K. Cheng, E. Salami, F. Gao, C. Li, X. Tong, Y. Lin, Y. Zhang, W. Zhang, L. Klinge, P. Walsh and Z. Fakhraai, "The effect of chemical structure on the stability of physical vapor deposited glasses of 1,3,5-triarylbenzene"J. Chem. Phys. 143, 084506 (2015). 

2.     Z. Qian, S.P. Hastings, C. Li, B. Edward, C.K. McGinn, N. Engheta, Z. Fakhraai* and S.J. Park, "Raspberry-like Metamolecules Exhibiting Strong Magnetic Resonances",  ACS Nano9, 1263-1270 (2015). 

3.     E. Glor, and Z. Fakhraai, "Facilitation of Interfacial Dynamics in Entangled Polymer Films", J. Chem. Phys. 141, 194505 (2014).

4.     Y. Lin, E.J. Peterson, and Z. Fakhraai, "Surface Effects Mediate Self-Assembly of Amyloid-β Peptides"ACS Nano8, 10178-10186 (2014).

5.     S. P. Hastings, P. Swanglap, Z. Qian, Y. Fang, S.J. Park, S. Link, N. Engheta, and Z. Fakhraai, "Quadrupole-Enhanced Raman Scattering", ACS Nano,  8 , 9025-9034 (2014).

6.     B. Sanchez-Gaytan, Z. Qian, S. Hastings, M. Reca, Z. Fakhraai, and S. J. Park, “Controlling
the Topography and Surface Plasmon Resonance of Gold Nanoshells by a Templated Surfactant-Assisted Seed Growth Method
 ”, J. Phys. Chem. C. 117, 8916-8923 (2013).

7.     C. R. Daley, Z. Fakhraai, M. D. Ediger, and J. A. Forrest, “Comparing Surface and Bulk Flow of a Molecular Glass Former”, Soft Matter, 8, 2206-2212 (2012). 

8.     M. Paulite, Z. Fakhraai, N. Gunari, A. Tanur, and G. C. Walker, “Imaging Secondary Structure of Individual Amyloid Fibrils of a β(2)-Microglobulin Fragment Using Near-Field Infrared Spectroscopy”, J. Am. Chem. Soc. 133, 7376-7383 (2011).

9.     Z. Fakhraai and J. A. Forrest, “Measuring the Surface Dynamics of Glassy Polymers”, Science, 319, 600- 604 (2008).

10.  Z. Fakhraai, and J. A. Forrest, “Probing Slow Dynamics in Supported Thin Polymer Films”, Phys. Rev. Lett. 95, 025701(2005).

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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