Past Seminars & Events

Professor Alison Wendlandt

Professor Alison Wendlandt
Department of Chemistry
Massachusetts Institute of Technology
Abstract

Selective catalytic isomerization reactions

Selective isomerization reactions are valuable tools for the positional and spatial interconversion of functional groups. Catalytic isomerizations are frequently governed by thermodynamic control, enabling predictable access to product distributions defined by the stability of starting and product isomers, but limiting opportunities for tunable control. Here, we describe a mechanistic framework to achieve kinetically controlled, contra-thermodynamic isomerization reactions in diverse synthetic contexts. Our work explores how the strategic application of these reactions in a late stage setting can facilitate the construction of complex organic molecules.

Alison Wendlandt

Professor Alison Wendlandt is an Associate Professor of Chemistry at the Massachusetts Institute of Technology. Alison is originally from Colorado, and received her B.S. from the University of Chicago and her Ph.D. from the University of Wisconsin - Madison under the guidance of Shannon Stahl. Alison was a postdoctoral fellow at Harvard University in the Jacobsen research group, until beginning her independent career at MIT in 2018. The Wendlandt group is interested in the development and mechanistic elucidation of new selective catalytic reactions.

Professor Blair Brettmann

Professor Blair Brettmann
Chemical and Biomolecular Engineering
Materials Science and Engineering
Georgia Institute of Technology
Abstract

Design for sustainability: pairing materials science with consumer behavior

Over U.S. consumers spent 4.5 trillion dollars on goods while generating 292 million tons of municipal solid waste in 2018 – and trends in both spending and waste generation are increasing. Displacing plastic-based materials with bio-sourced, re-processable or other more sustainable materials may be consistent with green chemistry and engineering design principles but does not truly improve the circular economy if the bio-sourced or re-processable materials travel straight to landfill. Thus, the challenge of designing products for enhanced sustainability must include a focus on both the materials chemistry aspects as well as the choices consumers make at the end of the product lifetime. To address the materials chemistry challenges, we look to expand available plastics with desirable mechanical properties that are recyclable by designing composites with covalent adaptable networks, including ones that incorporate particles. The interplay of the bond exchange rate kinetics and the network relaxation both greatly influence the reprocessability kinetics, showing that in such systems both the physical and chemical dials can be used to tune the system. However, these new materials will only enhance overall product sustainability if consumers return them for recycling. Thus, we develop a circular economy framework that includes a consumer gate – enabling inclusion of the value provided by the consumer’s decision to recycle into an overall model of the cost of manufacturing the product. By tackling the challenge of sustainable consumer goods from both the materials design and end-of-life perspectives, we can increase the impact of polymer research for sustainability.

Blair Brettmann

Blair Brettmann is an Associate Professor in Chemical and Biomolecular Engineering and Materials Science and Engineering at Georgia Tech. She received her B.S. in Chemical Engineering at the University of Texas at Austin and her Ph.D. in Chemical Engineering at MIT. Following her Ph.D., Dr. Brettmann was a Senior Research Engineer at Saint-Gobain and a postdoctoral researcher in the Institute for Molecular Engineering at the University of Chicago. She was the recipient of the NSF CAREER Award in 2021, the ACS PMSE Young Investigator award in 2020 and an IUPAC Young Observer in 2019. Her research focuses on linking molecular to micron scale phenomena to processing and multicomponent complex mixtures to enable rapid and science-driven formulation and product development.

Dr. Hannah S. Kenagy

Hannah S. Kenagy
Department of Civil & Environmental Engineering
Massachusetts Institute of Technology
Abstract

Impacts of peroxy radical chemistry on atmospheric organic aerosol production

Atmospheric aerosol particles impact climate by altering the Earth’s radiative balance and can be detrimental to human health when inhaled. Organic aerosol constitutes a large, and often dominant, fraction of the tropospheric aerosol mass, and much of that organic aerosol is secondary, produced from volatile organic compounds (VOCs) that are sufficiently oxidized in the atmosphere to be condensable. The amount and properties of secondary organic aerosol (SOA), which ultimately govern its air quality and climate impacts, are controlled by the complex kinetics, product distributions, and branching ratios along reaction pathways of organic oxidation. Here, I focus on a key branching point in the oxidation of VOCs that controls the production of SOA, namely the fate of organic peroxy radicals (RO2). First, I will discuss the contribution of organic nitrates (RONO2), a product of the reaction between RO2 and NO radicals, to urban organic aerosol using airborne field measurements over the Korean Peninsula in conjunction with simulations from an atmospheric chemical transport model. Second, I will describe new methods for model-informed experimental design that allow laboratory experiments of SOA production to access atmospheric distributions of RO2 fate for the first time.

Hannah S. Kenagy

Dr. Hannah S. Kenagy (she/her) is an atmospheric chemist currently working as an NSF Postdoctoral Fellow in the Department of Civil and Environmental Engineering at MIT. Kenagy first became interested in atmospheric chemistry during her undergraduate work at the University of Chicago and the University of Edinburgh before completing a PhD in Chemistry as an NSF Graduate Research Fellow at UC Berkeley. Kenagy’s research utilizes an integrated combination of measurement and modeling techniques to better understand chemical pathways in the atmosphere that contribute to the atmospheric oxidation capacity and the production and fate of air pollutants globally. Kenagy’s PhD work used a combination of airborne field measurements and modeling to better understand the urban chemistry of nitrogen oxides, pollutants emitted during combustion which impact the production of ozone and aerosol particles. In her postdoctoral work, Kenagy is integrating modeling and laboratory studies to disentangle the effects of multigeneration oxidation on the formation of atmospheric organic aerosols. Kenagy also enjoys mentoring students and fostering in them an excitement for atmospheric chemistry, as well as doing outreach to make science accessible to all.

Hosted by Professor Michael Bowser

Professor Eugene Y-X Chen

Professor Eugene Y-X Chen
Department of Chemistry
Colorado State University
Abstract

Sustainable Mono-Material Product Design with Circular and Biodegradable polymers

The traditional multi-material product design of plastic products, which typically employs multiple, often non- biodegradable or non-recyclable materials of different chemical speciation or composition, significantly complicates both mechanical, chemical, or other emerging recycling processes. In this seminar, I will discuss the emerging mono-material product design based on circular and/ or biodegradable polymers made of a single monomer, delivering tailorable properties characteristic of all common types of polymers via either molecular engineering of monomer structures or macromolecular engineering of polymer topologies and stereomicrostructures, but without changing their chemical makeup or composition.

Eugene Y-X Chen

Professor Eugene Chen received his undergraduate education in China and Ph.D. degree from The University of Massachusetts, Amherst, in 1995. After a postdoctoral stint at Northwestern University, he joined The Dow Chemical Company, where he was promoted from Sr. Research Chemist to Project Leader. Two and a half years later he moved to Colorado State University in August 2000, where currently he is a University Distinguished Professor, the John K. Stille Endowed Chair Professor in Chemistry, and the Millennial Professor of Polymer Science and Sustainability. His current research is centered on polymer science, sustainable chemistry, and molecular catalysis. Selected honors and awards include: Excellence in Commercialization Award by the Colorado Cleantech Industry Association; the Presidential Green Chemistry Challenge Award in 2015 by the US Government’s Environmental Protection Agency; and the Arthur Cope Mid-Career Scholar Award in 2019 by the American Chemical Society.

Hosted by Maggie Kumler and Violet Haas

Professor Sossina M. Haile

Professor Sossina M. Haile
Department of Materials Science & Engineering
Northwestern University
Abstract

Superprotonic Solid Acid Compounds for Sustainable Energy Technologies 

Superprotonic solid acid electrolytes, materials with chemical and physical properties intermediate between conventional acids (e.g., H3PO4) and conventional salts (e.g., Cs3PO4), have emerged as attractive candidates for fuel cell and other electrochemical applications. Key characteristics of these materials, which include CsHSO4, Cs3H(SeO4)2, CsH2PO4, and Cs2(HSO4)(H2PO4), are tetrahedral oxyanion groups linked by hydrogen bonds and a polymorphic structural transition to a disordered state at moderate temperatures. In the high temperature state, rapid oxyanion reorientation and dynamic disorder of the hydrogen bond network facilitate high proton conductivity. The transition to the structurally disordered phase is accompanied by a jump in conductivity by 3-5 orders of magnitude, and the activation energy for proton transport drops to a value of ~ 0.35 eV. Of materials displaying such behavior, CsH2PO4 is of particular technological significance is due to its chemical stability against both oxidation and reduction in device- relevant environments. We present here an overview of the proton transport characteristics of CsH2PO4 and the current status of electrochemical technologies in which it has been deployed. Material limitations translate into device limitations, motivating our efforts to develop and discover new superprotonic conductors. We show that dramatic changes in phase behavior and proton conductivity of the base phosphate can be induced by only minor changes in chemistry, suggesting routes for tuning behavior to achieve desired outcomes.

Sossina M. Haile

Sossina M. Haile is the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University, a position she assumed in 2015 after serving 18 years on the faculty at the California Institute of Technology. She earned her Ph.D. in Materials Science and Engineering from the Massachusetts Institute of Technology and as part of her training spent two years at the Max Planck Institute for Solid State Research in Stuttgart, Germany. Haile’s research broadly encompasses materials, especially oxides, for sustainable electrochemical energy technologies. Amongst her many awards, in 2008 Haile received an American Competitiveness and Innovation Fellowship from the U.S. National Science Foundation in recognition of “her timely and transformative research in the energy field and her dedication to inclusive mentoring, education and outreach across many levels.” In 2010 she was the recipient of the Chemical Pioneer Award (American Institute of Chemists), in 2012 the International Ceramics Prize (World Academy of Ceramics), and in 2020 the Turnbull Lectureship (Materials Research Society). She is a fellow of the Royal Society of Chemistry, the Materials Research Society, the American Ceramics Society, the African Academy of Sciences, and the Ethiopian Academy of Sciences, and serves on the editorial boards of MRS Energy and Sustainability and Joule. 

Hosted by Professor Andreas Stein 

Learn more about the Margaret C. Etter Memorial Lecture in Materials Chemistry

Professor Boone M. Prentice

Professor Boone M. Prentice
Department of Chemistry
University of Florida
Abstract

Revealing Molecular Pathology at High Chemical and Spatial Resolutions Using Mass Spectrometry

Imaging mass spectrometry is a powerful analytical technique for analyzing the spatial lipidome. This technology enables the visualization of molecular pathology directly in tissues by combining the specificity of mass spectrometry with the spatial fidelity of microscopic imaging. This label-free methodology has proven exceptionally useful in research areas such as cancer diagnosis, diabetes, and infectious disease. However, state- of-the-art experiments stress the limits of current analytical technologies, necessitating improvements in molecular specificity and sensitivity in order to answer increasingly complicated biological and clinical hypotheses. Especially when studying lipids, many isobaric (i.e., same nominal mass) and isomeric (i.e., same exact mass) compounds exist that complicate spectral analysis, with each structure having a potentially unique cellular function. The Prentice Lab develops instrumentation and novel gas- phase reactions to provide unparalleled levels of chemical resolution. These gas- phase transformations are fast, efficient, and specific, making them ideally suited for implementation into imaging mass spectrometry workflows. For example, these workflows have enabled the identification of multiple sn- positional phosphatidylcholine isomers, the separation of isobaric phosphatidylserines and sulfatides, and the identification of fatty acid double bond isomers using a variety of charge transfer and covalent ion/ion reactions as well as ion/electron and ion/ photon reactions. Working with biologists and clinicians, we then leverage these novel imaging technologies to understand the molecular events associated with important problems in human health, including infectious disease, diabetes, and neurodegenerative diseases.

Boone M. Prentice

Boone Prentice is Assistant Professor in the Department of Chemistry at the University of Florida. He received his B.S. in Chemistry from Longwood University (Farmville, VA), and completed his Ph.D. in Chemistry at Purdue University (West Lafayette, IN) under the mentorship of Prof. Scott McLuckey studying gas- phase ion/ ion reactions and ion trap instrumentation. He then completed his postdoctoral work in the Department of Biochemistry at Vanderbilt University (Nashville, TN) as an NIH NRSA fellow under the guidance of Prof. Richard Caprioli before joining the faculty at UF in 2018. He was awarded an NIH Focused Technology Research and Development R01 grant in 2020 and a JDRF Innovation Award in 2023 to support his research developing gas-phase reactions and imaging mass spectrometry technologies to study the molecular pathology of diabetes, infectious disease, neurodegeneration, and neuropharmacology. He was also awarded the 2022 Young Investigator Award from Eli Lilly and Company, which is an unsolicited award given annually by Eli Lilly’s Analytical Chemistry Academic Contacts Committee to recognize a “rising star” in analytical chemistry, and was highlighted as a 2023 Emerging Investigator by the Journal of the American Society for Mass Spectrometry and as a 2023 Young Investigator in (Bio-) Analytical Chemistry by Analytical and Bioanalytical Chemistry.

Dr. Suman Gunasekaran

Dr. Suman Gunasekaran
KIC Experimental Fellow
Kavli Institute at Cornell

Investigating molecules in strongly interacting electronic and photonic environments

When molecules strongly couple to external electronic or photonic states, new hybrid systems emerge with novel chemical and physical properties. In the first part of my talk, I will present experimental and theoretical results probing molecular junctions, which comprise a single molecule electronically coupled to two metal electrodes. The conductance of molecular junctions typically decreases exponentially with molecular length. I will show how the effects of resonance, interference, and delocalization can be harnessed to design highly conductive molecular wires that upend the conventional exponential decay law and exhibit uniform, and even increasing, conductance with length. In the second part of my talk, I will discuss the properties of molecules strongly coupled to a photonic state within an optical cavity. I will present a tunable microfluidic platform that I have developed to achieve strong light-matter coupling and investigate cavity-modified reactivity. I will also discuss the theoretical relationship between the hybrid light-matter states, i.e., polariton states, and the refractive index of the molecules within the cavity. This foundational derivation captures the effects of disorder and reveals the challenges of using strong light-matter coupling with large collections of molecules as a mechanism for cavity-modified reactivity. The two parts of my talk will cover my work to date investigating molecules in strongly interacting electronic and photonic environments.

Suman Gunasekaran

Dr. Suman Gunasekaran is an A. O. Beckman Postdoctoral Fellow at Cornell University. His current research, in the lab of Prof. Andrew Musser, explores the properties of molecules in optical cavities in the strong light- matter coupling regime. Suman completed his Ph.D. in Chemical Physics at Columbia University in 2021, under the guidance of Prof. Latha Venkataraman, where he investigated the mechanisms of electron transport in single-molecule circuits. Suman concurrently received his B.A. in Chemistry & Physics and M.S. in Applied Physics from Harvard University in 2016. During college, he spent a summer at the University of Minnesota fabricating nanofluidic devices in the lab of Prof. Kevin Dorfman. Originally from Madison, WI, Suman is excited by the prospect of returning to the Midwest to launch his independent career developing precision measurement techniques to investigate light-matter interactions at the single-molecule level.

Hosted by Professor Kenneth Leopold

Dr. Melissa Ramirez

Melissa Ramirez
California Institute of Technology
Abstract

Bridging Experimental and Computational Chemistry for the Development of Cycloaddition Cascades of Strained Alkynes and Oxadiazinones and Enantioselective NiCatayzed Spirocyclization of Lactones

Owing to tremendous technological advances, computational chemistry has evolved into a powerful tool for the development of reactions used to construct complex molecules. Computational models that allow chemists to predict the selectivity of a reaction are highly sought after because they enable rapid and efficient construction of intricate scaffolds. The first part of the presentation will detail computational studies onthe reaction of strained alkynes and arynes with oxadiazinones and the application of this reaction to the synthesis of non-symmetric polycyclic aromatic hydrocarbons. Several mechanistic aspects of the transformation were interrogated using density functional theory (DFT) calculations, including the differing reactivities of non-aromatic strained alkynes versus arynes. Experimental studies also demonstrated the rapid synthesis of polycyclic aromatic hydrocarbons, including tetracene and pentacene scaffolds, using this synthetic platform. 

The second part of the presentation will center on the development of an asymmetric Ni-catalyzed intramolecular cyclization of lactones to generate spirocyclic scaffolds using a combination of experiments and computations. DFT calculations provide insight on the formation of a Ni-bound lactone enolate that reacts with a pendant aryl nitrile to generate a new spirocyclic quaternary center and β-imino lactone. This work is anticipated to expand the application of Ni-catalyzed nitrile insertion for quaternary center generation and to enable the exploration of new chemical space in drug discovery. Altogether, the establishment of computational models in these two areas of research facilitates 1) the incorporation of arynes and cyclic alkynes in polycyclic aromatic hydrocarbon synthesis and 2) the application of Ni catalysis in the synthesis of spirocyclic scaffolds.

Melissa Ramirez

Dr. Melissa Ramirez obtained her B.A. in chemistry at the University of Pennsylvania in 2016, having worked as an undergraduate researcher in the laboratory of Professor Gary Molander. In 2021, she earned her Ph.D. in organic chemistry at the University of California, Los Angeles. During her doctoral studies, she was trained as a computational and synthetic organic chemist under the guidance ofProfessors Ken Houk and Neil Garg. Her Ph.D. research centered on investigating the reactivity of strained cyclic intermediates and the mechanism of pericyclic reactions for complex molecule synthesis. Currently, Dr. Ramirez is an NIH K99/R00 MOSAIC Scholar, NSF MPS-Ascend Fellow, and Caltech Presidential Postdoctoral Scholar in the laboratory of Professor Brian Stoltz where her research focuses on enantioselective quaternary center formation using experiments and computations.

Hosted by Professor Courtney Roberts

Dr. Anuvab Das

Anuvab Das
Department of Chemistry
California Institute of Technology
Abstract

Transient C–H Amination Intermediates: From Structural Characterization to Application in Biocatalysis

Defects Metal–ligand (M–L) multiply bonded complexes hold a central place in inorganic chemistry and catalysis. These species have played a critical role in the articulation of important bonding principles, and are critical intermediates in a variety of challenging chemical transformations. The reactivity of these species simultaneously renders them attractive intermediates for catalysis but challenging synthetic targets to observe and characterize. The first part of this talk will introduce novel photochemical strategies for generating reactive M–L fragments under conditions suitable for time-resolved or cryogenic steady-state characterization. This photochemistry facilitates the use of in situ crystallography to characterize transient intermediates via single-crystal-to-single-crystal transformation. These experiments represent a new paradigm in the characterization of reactive intermediates in catalysis. 

In the second part, we will explore how the principles of protein evolution can be leveraged to harness these transient intermediates for catalytic processes not naturally occurring. The engineering of heme proteins allows for the selective functionalization of inert C–H bonds, generating nitrogen-containing molecules from basic feedstock chemicals. This highlights the significant role of biocatalysis and protein engineering in contemporary synthesis.

Anuvab Das

Born and raised in India, Anuvab completed his B.Sc. and M.Sc. in Chemistry from Presidency College (Kolkata) and IIT Kharagpur, respectively. He then moved to the US to pursue his doctoral studies with Prof. David C. Powers at Texas A&M University. His graduate work focused on the characterization of reactive intermediates involved during nitrene transfer reactions, using in situ crystallography. At present, he is a postdoctoral scholar with Prof. Frances H. Arnold at Caltech, where he is working on the development and characterization of new-to-nature amination reactions with heme proteins.

Hosted by Professor Ian Tonks

Dr. Julia Oktawiec

Julia Oktawiec
Materials Science& Engineering
Northwestern University
Abstract

Structural Design of Proteomimetic Materials for Gas Separations and Therapeutics

Proteins have complex structures and dynamics that influence ligand binding. These include allosteric effects and the presentation of organized arrays of functional groups. Inspired by these mechanisms, in this talk I will first describe my efforts towards proteomimetic materials that selectively capture dioxygen. This work found that coupling metal-based electron transfer with secondary coordination sphere effects in a cobalt-based metal–organic framework leads to strong and reversible adsorption of O2. Moderate-strength hydrogen bonding stabilizes a cobalt(III)- superoxo species formed upon O2 adsorption. Notably, O2-binding in this material weakens as a function of loading, as a result of negative cooperativity arising from electronic effects within the extended framework lattice. This behavior extends the tunable properties that can be used to design metal–organic frameworks for adsorption-based applications. 

In the second part of the talk, I will share the development of structural design rules for peptide brush polymers. These systems, generated by graft-through living polymerization, show promise as therapeutic agents and tandem repeat protein mimics. Prior work has focused on polymers composed from disordered peptides, and so conformational information is limited. To obtain greater insight into the structure of these systems and how it is influenced by properties of the peptide brushes, I studied a library of polymers generated from different classes of folded peptides. Spectroscopy and X-ray scattering reveals that modulation of the hydrophobicity and folding of the peptide brush plays an important role in the conformation of the polymer. Molecular dynamics simulations performed by collaborators illuminate this relationship in greater detail, corroborating experimental results. This work provides principles for the design of polymer therapeutics to bind proteins through specific structural interactions.

Julia Oktawiec

Dr. Julia Oktawiec is currently a NIH NRSA postdoctoral research scholar at Northwestern University in Prof. Nathan Gianneschi’s group focusing on the design peptide brush polymers for applications as therapeutics and proteomimetic materials. Originally from New York City, she pursued her undergraduate studies at Columbia University. She obtained her PhD at UC Berkeley under Prof. Jeffrey Long targeting bioinorganic-inspired oxygen adsorption in metal–organic frameworks, graduating in 2019. She is excited about bioinspired materials, their structural design, and mimicking the mechanisms that biology uses to accomplish complex tasks.

Hosted by Professor Ian Tonks