CHESS DMR-0936384 2013_5_1

Look fast: Crystallization of conjugated molecules probed in-situ and in real timeJoel Brock, Cornell University, DMR 0936384

Detlef-M. Smilgies, Ruipeng Li, Gaurav Giri, Kang Wei Chou, Ying Diao, Zhenan Bao, and Aram Amassian: “Look fast – Crystallization of conjugated molecules during solution shearing probed in-situ and in real time by x-ray scattering”, Physica Status Solidi – Rapid Research Letters 7, 177-179 (2013).

Intellectual Merit: Organic transistors are being hotly investigated for flexible and inexpensive “plastic electronics” applications, such as automobile dashboards and smart tags. A joint team of scientists from the Cornell High Energy Synchrotron Source (CHESS), King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, and Stanford University just reported an experimental break-through for studying the structural evolution of organic transistor layers during the coating process in-situ and in real-time with x-ray scattering. The coating procedure, pictured on the cover graphic, resembles the buttering of a slice of toast turned high tech. A solution of a semiconducting molecule, called TIPS pentacene, is spread on a silicon substrate by the highly polished edge of a second silicon wafer. Precise control of the temperature of the substrate is key for this process. CHESS staff scientist Detlef Smilgies and Gaurav Giri, a graduate student in the Zhenan Bao research group at Stanford University, developed a miniature version suitable for the beamline of the full-scale coater developed at Stanford.

CHESS DMR-0936384 2013_5_2

Detlef-M. Smilgies, Ruipeng Li, Gaurav Giri, Kang Wei Chou, Ying Diao, Zhenan Bao, and Aram Amassian: “Look fast – Crystallization of conjugated molecules during solution shearing probed in-situ and in real time by x-ray scattering”, Physica Status Solidi – Rapid Research Letters 7, 177-179 (2013).

Broader Impacts: A joint team of scientists from the CHESS, KAUST, and Stanford University just reported an experimental break-through for studying the structural evolution of organic transistor layers during the coating process in-situ and in real-time with x-ray scattering. At a first glance solution shearing appears very similar to classic coating techniques used in industrial mass production, known as knife coating or doctor blading. The difference lies in the exquisite control of the coating parameters employed in solution shearing. In classic coating technology (typically liquid) films are deposited at a specific film thickness. While in solution shearing, the deposition of solid films occurs at the edge of the meniscus. With careful attention to the deposition parameters, solution shearing will be scalable to large-scale roll-to-roll processing. This capability will be essential for industrial-style production of solar cells, room lighting, and flexible displays based on organic electronics.

Effect of slow (A, B) and fast solution (C, D) shearing. The top panels show the detector images and the bottom panels the corresponding microscope images; a scale bar of 0.1 mm is shown in panel A. Images mark the beginning (A, C) and the end (B, D) of a solution shearing experiment. Initially only the liquid scattering ring is seen, then crystallization sets in, while the liquid scattering fades.

Look fast: Crystallization of conjugated molecules probed in-situ and in real timeJoel Brock, Cornell University, DMR 0936384

CHESS DMR-0936384 2013_5_3

Understanding the Spring-Loaded Rotary Motor Within Living Cells

Joel Brock, Cornell University, DMR 0936384

Oot, R. A., Huang, L. S., Berry, E. A and Wilkens, S. (2012) Crystal structure of the yeast vacuolar ATPase heterotrimeric EGC(head) peripheral stalk complex. Structure 20, 1881-92.

Intellectual Merit: The vacuolar ATPase (V-ATPase) is a large, multi-protein enzyme complex that pumps acid (protons) across lipid membranes in all animal and plant cells. It uses the main energy currency of the cell (adenosine triphosphate (ATP) via hydrolysis) to transport protons across biological membranes, a process that results in acidification of intracellular compartments (organelles) or the extracellular space. A fundamental question is the structural basis for the reversible dissociation. A key piece of the puzzle was recently provided by the X-ray crystal structure of the peripheral stalk subunits (EG) connected to the regulatory C subunit (head domain). The study was performed by Rebecca Oot in the Wilkens and Berry labs at SUNY Upstate Medical University using data collected at CHESS beamlines A1 and F1, and the results are reported in the journal, Structure. Flexibility and spring loading of the peripheral stalks. (a)

Alignment of the structures of the two conformations. (b) On the left is an electron microscopic (EM) reconstruction of the V-ATPase with the density belonging to the EGC complex in purple. (c) Schematic of the initiation of enzyme regulation by reversible dissociation.

CHESS DMR-0936384 2013_5_4

Oot, R. A., Huang, L. S., Berry, E. A and Wilkens, S. (2012) Crystal structure of the yeast vacuolar ATPase heterotrimeric EGC(head) peripheral stalk complex. Structure 20, 1881-92.

Broader Impacts: The vacuolar ATPase (V-ATPase) is a large, multi-protein enzyme complex that pumps acid (protons) across lipid membranes in all animal and plant cells. The structures presented here lend insight into the interactions between three V-ATPase subunits that are essential to the structural integrity of the enzyme. As the EGChead interaction is unique to the eukaryotic V-ATPase, the structures provide an important step toward a molecular understanding of the enzyme’s unique structure and regulation by reversible dissociation. Furthermore, the high level of conservation of eukaryotic V-ATPases suggests that the data presented here will provide a framework for further study of the role that the flexibility of the peripheral stalks may play in regulation and activity of the enzyme from other sources.

V-ATPase regulation and the X-ray structure of the EGC(head) complex. (a) Schematic of V-ATPase regulation by reversible dissociation showing the active assembled enzyme (left) and inactive dissociated enzyme (right). (b) of the EGC(head) complex is highly elongated (150 Å) with the regulatory C subunit bound on one end of the parallel EG heterodimer.

Understanding the Spring-Loaded Rotary Motor Within Living Cells

Joel Brock, Cornell University, DMR 0936384