Han receives DoD award to purchase X-ray diffraction instrument

Congratulations to Grace Han, Assistant Professor of Chemistry and Landsman Career Development Chair in the Sciences. She has been awarded funds from the Department of Defense to purchase a bench-top X-ray diffraction instrument. This award is part of the DoD’s Defense University Research Instrumentation Program (DURIP) that will provide $59 million in FY 2023 to purchase research equipment at 77 institutions across 30 states.

Changes in the properties of organic materials undergoing transition between solid and liquid phases are employed in a variety of applications, including thermal energy storage, cooling, and actuation. The ability to regulate such phase transitions by light opens up new opportunities to achieve functions with a high spatial precision, triggered by the rapid, remotely applied, and non-invasive stimulus. This capability enables novel applications including photo-controlled heat storage, adhesion, actuation, and catalyst recovery, which the Han group investigates.

The DURIP award from the Air Force Office of Scientific Research (AFOSR) and the Department of Defense (DoD) will enable the Han team to build a new research capability on campus. A non-ambient, benchtop X-ray diffractometer, equipped with light sources and a heating/cooling stage, will allow the group to study how molecules change their geometry and intermolecular interaction in response to irradiation and temperature change. This will yield a deep understanding of photoswitch designs that undergo facile structural changes in solid phase, assisting the discovery and development of light-responsive functional materials.

Division of Science Confers Degrees at 2022 Brandeis Commencement

Jane Kondev and students 2022 commencement

Jané Kondev, Professor of Physics, and students at the 2022 Brandeis commencement

Brandeis University held its 71st commencement on May 22nd. The 16 departments and programs that make up the Division of Science granted degrees at the bachelor’s, master’s and PhD levels.  There were 556 degrees granted to the undergraduates of the Division of Science. This was 41% of the total number of Brandeis undergraduate degrees conferred at the commencement.

Additionally, 47 PhD degrees from the Biochemistry and Biophysics, Chemistry, Computer Science, Mathematics, Molecular and Cell Biology, Neuroscience, Physics and Psychology program were awarded. These graduate programs as well as Computational Linguistics, Biotechnology, and Genetic Counseling granted 95 Master’s degrees.

Congratulations to all!

 

 

 

 

 

 

 

SciFest XI to be held on Thursday, 8/11/22

Save the Date for SciFest!

SciFest, the Division of Science’s annual celebration of undergraduate research, is a poster session featuring work done by undergraduates in Brandeis laboratories each summer. This is a capstone event for the undergraduate researchers where they can present the results of their research to peers, grad students, and faculty.

Join us for the SciFest XI which will be held on Thursday, August 11, 2022 in the Shapiro Science Center.

Grace Han and 2 Alumni Receive 2022 Sloan Foundation Fellowships

Grace Han group photo

Grace Han (left) and her group.

The Alfred P. Sloan Foundation has announced the winners of the 2022 Sloan Research Fellowships. These fellowships are awarded to early-career scientists that represent the most promising researchers working today. Winners receive $75,000, which can be used to support their research over a two-year term. Grace Han, Assistant Professor of Chemistry and the Landsman Career Development Chair in the Sciences is one of the 2022 recipients.

The major goal of Dr. Grace Han’s research program is to develop functional organic material systems that exhibit phase transitions triggered by external stimuli, notably light. The photo-controlled phase-change materials have a game-changing potential in waste heat recycling and storage, photo-actuation, photo-lithography, and photo-regulated adhesion. In particular, the novel strategy to optically ‘fix’ a liquid phase under fluctuating temperatures allows for a long-term latent heat storage and a triggered release of energy, which is not attainable by conventional phase-change materials such as paraffins or salt hydrates. To achieve this goal, her team investigates the photo-induced structural and polarity changes of molecular switches based on azobenzene, which reversibly controls the phase of materials.
The Sloan Research Fellowship will support the new direction of Han group’s research in expanding the materials set by the rational design of photoswitches with enhanced optical and thermal properties, which will address the challenges of the current state-of-the-art switches.
Two Brandeis alumni also received 2022 fellowships: Netta Engelhardt, BS ’11 (Physics) and Dapeng Bi, PhD ’12 (Physics).

Schmidt-Rohr examines why plants need two different photosystems

In a recent paper in Life (Basel), Klaus Schmidt-Rohr, Professor of Chemistry, introduces a self-explanatory description of the energetics of photosynthesis in plants, the so-called EZ-scheme. It shows the energies of molecules in kJ/mol instead of the classical Z-scheme’s shifted energy differences that are misleadingly encrypted in volts. Unlike its predecessor, the EZ-scheme includes the Kok cycle in the water-splitting complex, charge separation after photon absorption, and the Calvin cycle with carbohydrate synthesis (in a simplified form). It also shows O2 correctly as a high-energy product, due to its relatively weak double bond, and demonstrates that Photosystem II pumps more of the absorbed photon energy into O2 than into the plant.

This paper provides the first valid explanation of why plants need two different photosystems: PSII mostly extracts hydrogen (as protons plus electrons) from H2O, producing PQH2 (plastoquinol), and generates the energetically expensive product O2, providing little energy directly to the plant. PSI is needed to produce significant chemical energy for the organism, in the form of ATP, and to generate a less reluctant hydrogen donor, NADPH. This work fundamentally revises received notions of the energetics of photosynthesis, by pointing out the classical Z-scheme’s bewildering implication that H2O gives off electrons spontaneously to chlorophyll while releasing energy, and by showing that the concept of energy transport by “high-energy electrons” in photosynthesis is misguided, since energy and electrons flow in opposite directions.

Figure #1 from Schmidt-Rohr paper

Figure 1 Simplified EZ-scheme of the energetics of photosynthesis in plants, converting H2O and CO2 to O2 and carbohydrate, [CH2O]. The direction of energy transfer and release is indicated by straight red arrows at the top, formal hydrogen transfer by blue dashed curved arrows at the bottom of the diagram. Three dots … indicate omitted redox reactions.

Schmidt-Rohr K. O2 and Other High-Energy Molecules in Photosynthesis: Why Plants Need Two Photosystems. Life (Basel). 2021 Nov 5;11(11):1191.

Han paper describes electrochemical switching of arylazopyrazole & heat release

Research image from paperMihael Gerkman and Prof. Grace Han in the Department of Chemistry report the first demonstration of redox-induced energy release from molecular solar thermal (MOST) compounds in condensed phases, in collaboration with a team of Prof. Matthew Fuchter at Imperial College London. MOST compounds that utilize light-induced chemical isomerization for harnessing solar photon energy have emerged as an alternative to photovoltaics and artificial photosynthesis, enabling a closed-system solar photon energy storage and controlled release. Despite the discovery of various photoswitch systems that show improved photon energy storage efficiencies, the efficient and complete energy release from such photoswitches has remained a major challenge.

This work describes electrochemically-induced switching of arylazopyrazole-based photoswitches. The switching itself is electrocatalytic, requiring only a substoichiometric amount of charge, and its efficiency is improved by over an order of magnitude in the condensed phase compared to in solution. Moreover, electrochemically-induced switching affords a significantly higher completeness of switching than what could be achieved photochemically, which addresses the critical limitation of various azoheteroarene-based MOST materials. We envision that this work will promote exploration of the use of an electrical trigger for MOST material applications for a wide variety of photoswitches.

Jake L. Greenfield‡, Mihael A. Gerkman‡, Rosina S. L. Gibson, Grace G. D. Han*, and Matthew J. Fuchter* J. Am. Chem. Soc. 2021, 143, 37, 15250–15257. (‡ equal contributions) Publication Date: September 14, 2021.

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