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The Rubinstein Group

The Rubinstein Group

The research in the Rubinstein Group is in the field of polymer theory and computer simulations. The unique properties of polymeric systems are due to the size, topology and interactions of the molecules they are made of. Our goal is to understand the properties of various polymeric systems and to design new systems with even more interesting and useful properties. Our approach is based upon building and solving simple molecular models of different polymeric systems. The models we develop are simple enough to be solved either analytically or numerically, but contain the main features leading to unique properties of real polymers. Computer simulations of our models serve as an important bridge between analytical calculations and experiments.

 

The Meyer Group

The Meyer Group

The Meyer Lab has a wide range of research interests based in transition metal chemistry. We have multiple ongoing collaborations with professors in both biological to physical chemistry.

The unifying theme of our many projects is energy conversion. By studying the basic principles of electron transfer, excited states, and redox catalysis, we hope to advance the frontier of knowledge in renewable energy research. For example, we are currently investigating mechanisms of proton-coupled electron transfer, in order to understand how water is oxidized by Photosystem II during photosynthesis.

 

Cahoon Receives Packard Fellowship

We congratulate Assistant Professor James Cahoon as being one of eighteen national recipients of a David and Lucile Packard Foundation Fellowship. James was elected as one of the nation's most innovative early-career scientists and engineers receiving a 2014 Packard Fellowships for Science and Engineering. Each Fellow will receive a grant of $875,000 over five years to pursue their research.


James Cahoon

"The Packard Fellowships are an investment in an elite group of scientists and engineers who have demonstrated vision for the future of their fields and for the betterment of our society," said Lynn Orr, Keleen and Carlton Beal Professor at Stanford University, and Chairman of the Packard Fellowships Advisory Panel. "Through the Fellowships program, we are able to provide these talented individuals with the tools and resources they need to take risks, explore new frontiers and follow uncharted paths."

 

More Fluorine - Better Solar Cell Efficiency

Developing novel materials and device architectures to further enhance the efficiency of polymer solar cells requires a fundamental understanding of the impact of chemical structures on photovoltaic properties. Given that device characteristics depend on many parameters, deriving structure/property relationships has been very challenging.

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Through an international collaboration, members of the You Group discovered that a single parameter, hole mobility, determines the fill factor of bulk heterojunction photovoltaic devices in a series of copolymers with varying amount of fluorine substitution. The continuous increase of hole mobility upon further fluorination is related to a preferential face-on orientation and improved pi-pi stacking of the polymer backbones. The results shows the potential of properly-designed polymers to enable high fill factors in thick devices, as required by mass production technologies. These significant results appeared in JACS, and were also featured in JACS Spotlights.

 

Quantum Dynamics on Supercomputers

In the perspective paper published in Computing in Science and Engineering’s special topic issue on Advances in Leadership Computing, researchers in the Kanai Group and his collaborators at University of Illinois at Urbana Champaign and Lawrence Livermore National Laboratory describe the state-of-the-art computational method for simulating quantum dynamics of electrons in complex materials using supercomputers.

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They discuss a new first-principles computational method for simulating quantum dynamics of electrons in complex materials by propagating time-dependent wavefunctions. The method is designed to take advantage of a large number of processing cores in today’s supercomputers by utilizing multiple levels of different parallelization schemes. They demonstrate a strong scaling of the computational method over 1 million processing cores on an IBM supercomputer. As an example of how new material properties can be investigated using this state-of-the-art method, non-equilibrium energy transfer rate from a fast proton to the electronic excitation in bulk gold was calculated and compared to available experimental data. Importantly, the computer simulation provides detail information on how the electronic excitation is induced by the fast proton. This new first-principles quantum dynamics method enables theoretical investigations into various non-equilibrium phenomena of electrons in large complex systems.

 

Meyer Wins Samson Award

As announced by Israeli Prime Minister Benjamin Netanyahu on October 6th, Arey Distinguished Professor of Chemistry, Thomas Meyer, is one of two winners of the 2014 Eric and Sheila Samson Prime Minister's Prize for Innovation in Alternative Fuels for Transportation. Professor Meyer is recognized as a world leader in solar fuel research.

Professor Thomas Meyer

The $1 million prize is awarded for breakthrough work into converting solar energy into electricity capable of powering transportation. "We are making a major multi-year effort so that we will not be dependent on fluctuations in the price of oil," Netanyahu said. "This prize gives the researchers true appreciation for their efforts." The Eric and Sheila Samson Prize, totaling $1 million, is the world’s largest monetary prize awarded in the field of alternative fuels, and is granted to scientists who have made critical advancements."

Congratulations to Dr. Meyer on receiving such a prestigious international honor," said UNC Chancellor Carol L. Folt. "Dr. Meyer is a superb example of the kind of innovation we champion here at UNC, using research to solve the world's most pressing problems. By pairing a basic scientific knowledge of photosynthesis with the latest advances in nanotechnology, Dr. Meyer and his team are bringing the world closer than ever to making solar energy a practical, reliable power source."

 

RNA Structure in 3D

RNA molecules function as the central conduit of information transfer in biology. To do this, they encode information both in their sequences and in their higher-order structures. Understanding the higher-order structure of RNA remains challenging and slow. In work reported in PNAS and highlighted in Science, Phil Homan in the Weeks Lab led a collaboration that devised a simple, experimentally concise, and accurate approach for examining higher-order RNA structure.

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The researchers used massively parallel sequencing to invent an easily implemented single-molecule experiment for detecting through-space interactions and multiple conformations in RNA. This strategy, called RING-MaP, can be used to analyze higher-order RNA structure, detect biologically important hidden states, and refine accurate three-dimensional structure models.

 

Phototherapeutics

Light-activatable drugs offer the promise of controlled release with exquisite temporal and spatial resolution. However, light-sensitive prodrugs are typically converted to their active forms using short-wavelength irradiation, which displays poor tissue penetrance. Researchers in the David Lawrence Group report in Angewandte Chemie, International Edition, on erythrocyte-mediated assembly of long-wavelength-sensitive phototherapeutics.

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The activating wavelength of the constructs is readily preassigned by using fluorophores with the desired excitation wavelength λex. Drug release from the erythrocyte carrier was confirmed by standard analytical tools and by the expected biological consequences of the liberated drugs in cell culture: methotrexate, binding to intracellular dihydrofolate reductase; colchicine, inhibition of microtubule polymerization; dexamethasone, induced nuclear migration of the glucocorticoid receptor.

 

 

At the Department of Chemistry, we feel strongly that diversity is crucial to our pursuit of academic excellence, and we are deeply committed to creating a diverse and inclusive community. We support UNC's policy, which states that "the University of North Carolina at Chapel Hill is committed to equality of opportunity and pledges that it will not practice or permit discrimination in employment on the basis of race, color, gender, national origin, age, religion, creed, disability, veteran's status, sexual orientation, gender identity or gender expression."